dhcp ip address assignment process

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What is dhcp (dynamic host configuration protocol).

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Samsung's new galaxy ring makes health tracking simple, tech deals: jbl bar 700, amazon fire max tablet, video doorbell, and more, quick links, dhcp can handle ip assignments, dhcp controls the range of ip addresses, dynamically assigned addresses are temporary, static ip addresses are necessary for some devices, key takeaways.

• DHCP automates the process of assigning IP addresses to devices connecting to a network, making it easier to connect multiple devices.
• DHCP allows you to control the range of IP addresses available for use, ensuring you can limit the number of devices connected to your network.
• While DHCP assigns IP addresses temporarily, static IP addresses are necessary for certain devices (e.g. servers) to maintain consistent connectivity and configuration.

The Dynamic Host Configuration Protocol (DHCP) is integral to networks and controls what IP addresses devices receive so they can communicate with the internet. Usually, IP assignment is automated, but if you need static IPs, familiarity with DHCP is essential.

Every device that connects to a network needs an IP address . In the early days of networking, users manually assigned themselves an IP address, but that's a cumbersome task, especially for places with many devices, such as a corporate office. DHCP, in part, automates this process, which makes connecting devices to the network far easier. DHCP servers or routers handle this process based on a set of defined rules. Most routers are set to use a 192.168.0.x range, for instance, so you'll commonly see IP addresses like this in home networks.

The process is pretty straight forward. When a client (a computer, IOT device , tablet, cell phone, etc.) connects to the network, it sends out a signal (called DHCPDISCOVER) to the DHCP server (or router). The server responds with all the rules and settings for the network and an IP address for use (a DHCPOFFER). The client acknowledges the information and asks permission to use the assigned address (a DHCPREQUEST message). Finally, the DHCP server acknowledges the request, and the client is free to connect to the network.

You can configure DHCP to control the range of IP addresses available for use. If you state that range as starting at 192.168.0.1 and the end as 192.168.0.100, then all available addresses will fall somewhere within that range. You'll never see a device assigned to 192.168.0.101. Also, bear in mind that the start IP (192.168.0.1 in this example) is reserved for the router. Some routers only list a starting address and then include an option for a maximum number of users (which determines the end address).

The upside to this is you can control how many devices connect to your network simultaneously (no more than 100 in this example). But the downside is if you set the range too small you can unintentionally prevent connection of new devices. To allow for a lower range of IP addresses, DHCP servers only lease out IP addresses to devices.

When a DHCP server assigns an IP Address, it does so under a lease system. The machine retains this IP address for a set number of days, after which it can try to renew the IP address. If no renewal signal is sent (such as a decommissioned machine), then the DHCP server reclaims the IP address to assign to another device. When the renewal signal is detected, the device retains its IP address for another set of days. This is why your IP address may appear to change from time to time if you use the ipconfig option often.

It's possible for two devices to end up with the same IP, such as a virtual machine (VM) that spends most of its time offline. The VM won't be able to send the renew signal, so its IP address will be handed out to another machine. When the VM is brought back up, it still has a record of the old IP address (especially if restored from a snapshot), but it won't be able to use that IP address since it is taken. Without that permission, it can't connect to the network until a new IP is assigned. But using dynamic IP addresses should prevent this type of scenario.

If you have a network connected printer or media server (such as a NAS unit Plex Server, or game server), it would be inconvenient for them to have their IP addresses changed. Sometimes hosted services require special configuration to function correctly. For example, a Minecraft server requires that port 25565 is forwarded , and you may have software pointing to your NAS's local IP. If the local IP of the device changes, then any rules (like port forwards) applied to it won't work anymore.

While renewal of the lease can prevent this, it's still possible for the IP address to change. If your router is restarted, due to a power outage or because you're trying to solve a pesky problem , then all Dynamically generated IP addresses may be reassigned. For those scenarios, manually assigning a Static IP address will solve the problem.

The exact process for this varies, especially as router web interfaces can change from device to device even when made by the same manufacturer. On some routers, like the Eero Mesh Router kit , this may be referred to by another term, such as IP reservation. But a static IP address still needs to conform to any range rules, if they exist. Using a current IP address as the basis for a static IP is usually the easiest thing to do. Depending on the device and its Operating System, it may be possible to set a static IP at the device end instead of through the router or DHCP server. This may be necessary if the router itself doesn't support Static IP.

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How DHCP works Explained with Examples

When a host (DHCP client) needs an IP configuration, it connects to a DHCP server and requests an IP configuration. A DHCP server contains several pre-configured IP configurations. When it receives a DHCP request from a DHCP client, it provides an IP configuration to the client from all available IP configurations.

This process goes through four steps: Discover, Offer, Request, and Acknowledgment.

The following image shows all four steps of a DHCP communication.

DHCP discovery

When we start a device, it checks whether a valid IP configuration is available. If it is not available, the device generates a special message known as the DHCPDISCOVER message and broadcasts this message on the local LAN segment.

In this message, the device uses the addresses 0.0.0.0 and 255.255.255.255 in the source and destination address fields, respectively.

The 0.0.0.0 and 255.255.255.255 are two special addresses. Any device, whether it has a valid IP configuration or not, can use these addresses to send local broadcast messages.

From these addresses, the 0.0.0.0 is used as the source address. If a device does not have the source address, it can use this address to send broadcast messages. 255.255.255.255 is the local broadcast address. Any message sent to this address is received by all hosts of the local network.

Since the client sends the DHCPDISCOVER message to the local broadcast address, if a DHCP server is configured on the local network, it will also receive the message. If multiple DHCP servers are configured on the local network, they all will receive the DHCPDISCOVER message.

If multiple DHCP servers are available, based on their configuration, one of them or all of them can reply to the DHCPDISCOVER message. In reply to the DHCPDISCOVER message, a DHCP server sends a DHCPOFFER message to the client.

Since the client does not have an IP address, the DHCP server cannot send the DHCPOFFER message directly to the client. Because of this, the server sets the destination address to 255.255.255.255 . In other words, the server also broadcasts the DHCPOFFER message to the local network.

The DHCPOFFER message includes protocol-specific information and an IP address, subnet mask, default gateway's IP address, DNS server's IP address, and other configured servers' IP addresses such as TFTP and FTP.

Apart from these, the DHCPOFFER message also contains other protocol-specific information such as the lease duration and client ID. This information is required by the core functions of DHCP.

DHCP request

All hosts in the local network receive the DHCPOFFER message. The host that sent the DHCPDISCOVER message accepts the DHCPOFFER message. Apart from the original host, all other hosts ignore the DHCPOFFER .

How does a host know whether the broadcasted DHCPOFFER message is for it?

The DHCPDISCOVER message contains the host's MAC address. When a DHCP server broadcasts a DHCPOFFER message, it also includes the host's MAC address in a parameter known as the client ID. When hosts receive the DHCPOFFER message, they check the client ID field in the message. If a host sees its MAC address in the client ID field, it knows the message is intended for it. If a host sees the MAC address of another host in the client ID field, it knows the message is not intended for it.

Depending on the number of DHCP servers, a host may receive multiple DHCPOFFER messages. If a host receives multiple DHCPOFFER messages, it accepts only one message and tells the corresponding server with a DHCPREQUEST message that it wants to use the offered IP configuration.

If only one DHCP server is available and the provided IP configuration conflicts with the client’s configuration, the client can respond with a DHCPDECLINE message. In this situation, the DHCP server offers another IP configuration.

When DHCP servers receive the DHCPREQUEST message, besides the server whose offer has been accepted, all other servers withdraw their offer and return them to the pool of available addresses.

The DHCPREQUEST message contains a Transaction ID field. Just like hosts use the client ID field of the DHCPOFFER message to know whether the message is intended for them or not, DHCP servers use the Transaction ID field of the DHCPREQUEST message to know whether their offer has been accepted or not.

DHCP acknowledgment

When the DHCP server receives a DHCPREQUEST message from the client, the configuration process enters its final stage. In this stage, the server sends a DHCPACK message to the client.

The DHCPACK message is an acknowledgment to the client indicating that the DHCP server has received the DHCPREQUEST message of the client, and the client can use the offered IP configuration.

In some cases, the server may also respond with a DHCPNACK message. The DHCPNACK message tells the client that the offer is no longer valid and the client needs to request an IP configuration again. Typically, this occurs when the client takes too long to respond with a DHCPREQUEST message after receiving a DHCPOFFER message from the server. In such a case, the client can make a new request for another IP configuration.

The following image shows the above steps.

The following table summarizes messages that are used in each stage.

An easy way to remember these messages in the correct order is to think of the popular children's show "Dora the Explorer".

Each letter of the spelling DORA corresponds with the first letter of each step: D (Discover), O (Offer), R (Request), and A (Acknowledgment). Just as DORA discovers new things in her show, a DHCP client discovers a new IP configuration in the process.

This tutorial is the second part of the article 'DHCP (Dynamic Host Configuration Protocol) basic concepts, configurations, functions, and options Explained'. Other parts of this tutorial are the following.

What DHCP is and Types of DHCP Explained DHCP Configuration Parameters and Settings Explained How to Configure DHCP Server on Cisco Switches Configure DHCP Server for multiple VLANs on the Switch How to Configure DHCP Server on Cisco Routers How DHCP Relay Agents work Explained How to Configure DHCP Relay Agent on Cisco Routers How DHCP Snooping works Explained Configure DHCP Snooping on Cisco Switches

That's all for this tutorial. In the next part of this tutorial, we will understand DHCP configuration parameters and settings in detail.

By ComputerNetworkingNotes Updated on 2024-06-09

ComputerNetworkingNotes CCNA Study Guide How DHCP works Explained with Examples

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Understanding IP Address Assignment: A Complete Guide

Introduction

In today's interconnected world, where almost every aspect of our lives relies on the internet, understanding IP address assignment is crucial for ensuring online security and efficient network management. An IP address serves as a unique identifier for devices connected to a network, allowing them to communicate with each other and access the vast resources available on the internet. Whether you're a technical professional, a network administrator, or simply an internet user, having a solid grasp of how IP addresses are assigned within the same network can greatly enhance your ability to troubleshoot connectivity issues and protect your data.

The Basics of IP Addresses

Before delving into the intricacies of IP address assignment in the same network, it's important to have a basic understanding of what an IP address is. In simple terms, an IP address is a numerical label assigned to each device connected to a computer network that uses the Internet Protocol for communication. It consists of four sets of numbers separated by periods (e.g., 192.168.0.1) and can be either IPv4 or IPv6 format.

IP Address Allocation Methods

There are several methods used for allocating IP addresses within a network. One commonly used method is Dynamic Host Configuration Protocol (DHCP). DHCP allows devices to obtain an IP address automatically from a central server, simplifying the process of managing large networks. Another method is static IP address assignment, where an administrator manually assigns specific addresses to devices within the network. This method provides more control but requires careful planning and documentation.

Considerations for Efficient IP Address Allocation

Efficient allocation of IP addresses is essential for optimizing network performance and avoiding conflicts. When assigning IP addresses, administrators need to consider factors such as subnetting, addressing schemes, and future scalability requirements. By carefully planning the allocation process and implementing best practices such as using private IP ranges and avoiding overlapping subnets, administrators can ensure smooth operation of their networks without running out of available addresses.

IP Address Assignment in the Same Network

When two routers are connected within the same network, they need to obtain unique IP addresses to communicate effectively. This can be achieved through various methods, such as using different subnets or configuring one router as a DHCP server and the other as a client. Understanding how IP address assignment works in this scenario is crucial for maintaining proper network functionality and avoiding conflicts.

Basics of IP Addresses

IP addresses are a fundamental aspect of computer networking that allows devices to communicate with each other over the internet. An IP address, short for Internet Protocol address, is a unique numerical label assigned to each device connected to a network. It serves as an identifier for both the source and destination of data packets transmitted across the network.

The structure of an IP address consists of four sets of numbers separated by periods (e.g., 192.168.0.1). Each set can range from 0 to 255, resulting in a total of approximately 4.3 billion possible unique combinations for IPv4 addresses. However, with the increasing number of devices connected to the internet, IPv6 addresses were introduced to provide a significantly larger pool of available addresses.

IPv4 addresses are still predominantly used today and are divided into different classes based on their range and purpose. Class A addresses have the first octet reserved for network identification, allowing for a large number of hosts within each network. Class B addresses reserve the first two octets for network identification and provide a balance between network size and number of hosts per network. Class C addresses allocate the first three octets for network identification and are commonly used in small networks.

With the depletion of available IPv4 addresses, IPv6 was developed to overcome this limitation by utilizing 128-bit addressing scheme, providing an enormous pool of potential IP addresses - approximately 3.4 x 10^38 unique combinations.

IPv6 addresses are represented in hexadecimal format separated by colons (e.g., 2001:0db8:85a3:0000:0000:8a2e:0370:7334). The longer length allows for more efficient routing and eliminates the need for Network Address Translation (NAT) due to its vast address space.

Understanding these basics is essential when it comes to assigning IP addresses in a network. Network administrators must consider various factors such as the number of devices, network topology, and security requirements when deciding on the IP address allocation method.

In the next section, we will explore different methods of IP address assignment, including Dynamic Host Configuration Protocol (DHCP) and static IP address assignment. These methods play a crucial role in efficiently managing IP addresses within a network and ensuring seamless communication between devices.

Methods of IP Address Assignment

IP address assignment is a crucial aspect of network management and plays a vital role in ensuring seamless connectivity and efficient data transfer. There are primarily two methods of assigning IP addresses in a network: dynamic IP address assignment using the Dynamic Host Configuration Protocol (DHCP) and static IP address assignment.

Dynamic IP Address Assignment using DHCP

Dynamic IP address assignment is the most commonly used method in modern networks. It involves the use of DHCP servers, which dynamically allocate IP addresses to devices on the network. When a device connects to the network, it sends a DHCP request to the DHCP server, which responds by assigning an available IP address from its pool.

One of the key benefits of dynamic IP address assignment is its simplicity and scalability. With dynamic allocation, network administrators don't have to manually configure each device's IP address. Instead, they can rely on the DHCP server to handle this task automatically. This significantly reduces administrative overhead and makes it easier to manage large networks with numerous devices.

Another advantage of dynamic allocation is that it allows for efficient utilization of available IP addresses. Since addresses are assigned on-demand, there is no wastage of unused addresses. This is particularly beneficial in scenarios where devices frequently connect and disconnect from the network, such as in public Wi-Fi hotspots or corporate environments with a high turnover rate.

However, dynamic allocation does have some drawbacks as well. One potential issue is that devices may receive different IP addresses each time they connect to the network. While this might not be an issue for most users, it can cause problems for certain applications or services that rely on consistent addressing.

Additionally, dynamic allocation introduces a dependency on the DHCP server. If the server goes down or becomes unreachable, devices will not be able to obtain an IP address and will be unable to connect to the network. To mitigate this risk, redundant DHCP servers can be deployed for high availability.

Static IP Address Assignment

Static IP address assignment involves manually configuring each device's IP address within the network. Unlike dynamic allocation, where addresses are assigned on-demand, static assignment requires administrators to assign a specific IP address to each device.

One of the main advantages of static IP address assignment is stability. Since devices have fixed addresses, there is no risk of them receiving different addresses each time they connect to the network. This can be beneficial for applications or services that require consistent addressing, such as servers hosting websites or databases.

Static assignment also provides greater control over network resources. Administrators can allocate specific IP addresses to devices based on their requirements or security considerations. For example, critical servers or network infrastructure devices can be assigned static addresses to ensure their availability and ease of management.

However, static IP address assignment has its limitations as well. It can be time-consuming and error-prone, especially in large networks with numerous devices. Any changes to the network topology or addition/removal of devices may require manual reconfiguration of IP addresses, which can be a tedious task.

Furthermore, static allocation can lead to inefficient utilization of available IP addresses. Each device is assigned a fixed address regardless of whether it is actively using the network or not. This can result in wastage of unused addresses and may pose challenges in scenarios where addressing space is limited.

In order to efficiently allocate IP addresses within a network, there are several important considerations that need to be taken into account. By carefully planning and managing the allocation process, network administrators can optimize their IP address usage and ensure smooth operation of their network.

One of the key factors to consider when assigning IP addresses is the size of the network. The number of devices that will be connected to the network determines the range of IP addresses that will be required. It is essential to accurately estimate the number of devices that will need an IP address in order to avoid running out of available addresses or wasting them unnecessarily.

Another consideration is the type of devices that will be connected to the network. Different devices have different requirements in terms of IP address assignment. For example, servers and other critical infrastructure typically require static IP addresses for stability and ease of access. On the other hand, client devices such as laptops and smartphones can often use dynamic IP addresses assigned by a DHCP server.

The physical layout of the network is also an important factor to consider. In larger networks with multiple subnets or VLANs, it may be necessary to segment IP address ranges accordingly. This allows for better organization and management of IP addresses, making it easier to troubleshoot issues and implement security measures.

Security is another crucial consideration when allocating IP addresses. Network administrators should implement measures such as firewalls and intrusion detection systems to protect against unauthorized access or malicious activities. Additionally, assigning unique IP addresses to each device enables better tracking and monitoring, facilitating quick identification and response in case of any security incidents.

Efficient utilization of IP address ranges can also be achieved through proper documentation and record-keeping. Maintaining an up-to-date inventory of all assigned IP addresses helps prevent conflicts or duplicate assignments. It also aids in identifying unused or underutilized portions of the address space, allowing for more efficient allocation in the future.

Furthermore, considering future growth and scalability is essential when allocating IP addresses. Network administrators should plan for potential expansion and allocate IP address ranges accordingly. This foresight ensures that there will be sufficient addresses available to accommodate new devices or additional network segments without disrupting the existing infrastructure.

In any network, the assignment of IP addresses is a crucial aspect that allows devices to communicate with each other effectively. When it comes to IP address assignment in the same network, there are specific considerations and methods to ensure efficient allocation. In this section, we will delve into how two routers in the same network obtain IP addresses and discuss subnetting and IP address range distribution.

To understand how two routers in the same network obtain IP addresses, it's essential to grasp the concept of subnetting. Subnetting involves dividing a larger network into smaller subnetworks or subnets. Each subnet has its own unique range of IP addresses that can be assigned to devices within that particular subnet. This division helps manage and organize large networks efficiently.

When it comes to assigning IP addresses within a subnet, there are various methods available. One common method is manual or static IP address assignment. In this approach, network administrators manually assign a specific IP address to each device within the network. Static IP addresses are typically used for devices that require consistent connectivity and need to be easily identifiable on the network.

Another widely used method for IP address assignment is Dynamic Host Configuration Protocol (DHCP). DHCP is a networking protocol that enables automatic allocation of IP addresses within a network. With DHCP, a server is responsible for assigning IP addresses dynamically as devices connect to the network. This dynamic allocation ensures efficient utilization of available IP addresses by temporarily assigning them to connected devices when needed.

When considering efficient allocation of IP addresses in the same network, several factors come into play. One important consideration is proper planning and design of subnets based on anticipated device count and future growth projections. By carefully analyzing these factors, administrators can allocate appropriate ranges of IP addresses for each subnet, minimizing wastage and ensuring scalability.

Additionally, implementing proper security measures is crucial when assigning IP addresses in the same network. Network administrators should consider implementing firewalls, access control lists (ACLs), and other security mechanisms to protect against unauthorized access and potential IP address conflicts.

Furthermore, monitoring and managing IP address usage is essential for efficient allocation. Regular audits can help identify any unused or underutilized IP addresses that can be reclaimed and allocated to devices as needed. This proactive approach ensures that IP addresses are utilized optimally within the network.

The proper assignment of IP addresses is crucial for maintaining network security and efficiency. Throughout this guide, we have covered the basics of IP addresses, explored different methods of IP address assignment, and discussed considerations for efficient allocation.

In conclusion, understanding IP address assignment in the same network is essential for network administrators and technical professionals. By following proper allocation methods such as DHCP or static IP assignment, organizations can ensure that each device on their network has a unique identifier. This not only enables effective communication and data transfer but also enhances network security by preventing unauthorized access.

Moreover, considering factors like subnetting, scalability, and future growth can help optimize IP address allocation within a network. Network administrators should carefully plan and allocate IP addresses to avoid conflicts or wastage of resources.

Overall, a well-managed IP address assignment process is vital for the smooth functioning of any network. It allows devices to connect seamlessly while ensuring security measures are in place. By adhering to best practices and staying updated with advancements in networking technology, organizations can effectively manage their IP address assignments.

In conclusion, this guide has provided a comprehensive overview of IP address assignment in the same network. We hope it has equipped you with the knowledge needed to make informed decisions regarding your network's IP address allocation. Remember that proper IP address assignment is not only important for connectivity but also plays a significant role in maintaining online security and optimizing network performance.

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What is DHCP (Dynamic Host Configuration Protocol)?

Servers and clients use Dynamic Host Configuration Protocol to automatically assign IP addresses within a network.

The answer to “What is DHCP?” is that it’s the standard mechanism to dynamically assign IP addresses within a network. It stands for Dynamic Host Configuration Protocol.

IP, or Internet Protocol, addressing is a logical means of assigning addresses to devices on a network. Each device connected to a network requires a unique IP address.

At home, dynamic host configuration protocol (DHCP) assigns IP addresses to your smartphones, laptops, tablets, and devices like doorbell cameras. When you use wifi on your home network, typically your router is a DHCP server.

In a large enterprise setting, a DHCP server is usually a dedicated computer. By simplifying IP address management, it saves money, is more secure, and doesn’t eat up valuable admin time.

In this glossary entry, we’ll explore the fundamentals of how DHCP works. Then, we’ll take a deeper look at two aspects: dynamic addressing and the communications protocol.

How does DHCP work?

DHCP is a network management protocol. A client device (or DHCP client), such as a laptop, joins a network and requests an IP address. The request is made to a DHCP server.

These servers are often configured with redundancy—often called DHCP failover —or clustering among other network servers. Servers can run on both IPv4 and IPv6 networks.

The server will quickly and automatically assign an IP address and some related network configuration parameters. Once the device has accepted the assignment, it can communicate with both the internal network and the public internet.

Relevant parameters

In addition to assigning IP addresses, these servers also provide relevant parameters, known as DHCP options. The Internet Assigned Numbers Authority (IANA), the global coordinator of IP addresses, defines available DHCP parameters .

Options number in the hundreds. Key among them is how long the IP address can be used—known as the lease time. They also include the default gateway, its subnet mask, and its DNS server.

Some additional definitions

To clarify, let’s quickly define some of these terms we just mentioned:

• A default gateway transfers data back and forth between the local network and the internet, or between local subnets.
• IP networking uses a subnet mask to separate the host address and the network address portions of an IP address.
• A DNS server resolves names to IP addresses, translating domain names that we easily remember, like bluecatnetworks.com, into IP addresses like 104.239.197.100.

Dynamic IP addressing with DHCP

The assignment of IP addresses happens dynamically within a given address range. As a result, a device connected to the network doesn’t have a forever address. The IP address can periodically change as its lease time expires unless the lease is successfully renewed.

For services that always need to be on, a static IP address is often a better option. Corporate enterprises commonly use static IP addresses for hardware like mail servers. Certainly, a DHCP server should have a static IP address.

However, there are drawbacks to dedicating a specific IP address to a device or service. A network administrator must manually assign, configure, and track the IP address. It’s a time-consuming task. Oftentimes, it requires the admin to physically be with the device.

Meanwhile, dynamic IP addresses are usually the preferred choice because they:

• Cost less to manage than static IP addresses;
• May offer more privacy and security with a constantly changing IP address; and
• Don’t require manual administration when a device roams from one subnet to another.

DHCP communications protocol

Communications to fulfill a DHCP request involves both the server and client. Furthermore, a relay agent or IP helper often facilitates communication between the two. Relay agents receive broadcast DHCP messages from clients and then re-send those messages with configuration information to servers.

Communication happens via small units of data, called packets, that are routed through a network. Networking protocols like IP govern all its rules.

Most of the time, communication occurs in four steps. Briefly, they are:

• A discover packet is sent from the client to the server.
• The server replies to the client with a DHCP offer packet containing an IP address.
• The client receives and validates the offer, then sends a request packet back to the server to accept the address.
• The server sends an acknowledgement packet back to the client to confirm the chosen IP address.

With this in mind, one final point: DHCP alongside DNS and IP address management ( IPAM ) are together known as DDI.

Want to know how to define DDI or how it works to form a complete management solution? BlueCat’s Unified DDI solution is the place to start.

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What Is Dynamic Host Configuration Protocol (DHCP)?

Learn how DHCP works, what it does, and why it is important.

Dynamic Host Configuration Protocol (DHCP) Meaning

What is DHCP? Dynamic Host Configuration Protocol (DHCP) is used to dynamically assign Internet Protocol (IP) addresses to each host on your organization's network. In this DHCP meaning, a host can refer to any device that enables access to a network. Some examples include desktop computers and laptops, thin clients, and personal devices, among others. DHCP ensures all of these devices get assigned an IP address .

In the context of this DHCP definition, DHCP also assigns Domain Name System (DNS) addresses, subnet masks, and default gateways. All of these enable devices to communicate with the internet and each other within the confines of your network.

How Does the Dynamic Host Configuration Protocol (DHCP) Work?

DHCP protocols send messages to devices that connect to your network, providing them with what they need to interface with essential network functions. Imagine if you have a small home network that allows your laptop, your tablet, and your phone to connect to it. If you have to assign an IP address to each one, that may not be too difficult, especially because there are only three devices.

On the other hand, assigning IP addresses, as well as subnet masks, DNS addresses, and other essential data would take far too much work and time if you have to do so for a few hundred devices. DHCP automatically provides this information to all of the devices that connect to your network.

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DHCP Components

The primary DHCP components include a DHCP server, client, and relay.

DHCP server

A DHCP server is what the system uses to automatically provide IP addresses and additional network parameters to the devices that connect to your network. It is able to provide temporary or dynamic IP addresses taken from a pool of available addresses.

In addition, a DHCP server gives permanent IP addresses and DHCP configuration parameters, including those pertaining to subnet masks, default gateways, and DNS servers.

DHCP client

A DHCP client is a device that acts as a host, and it receives the information sent from the DHCP server. This includes any device that can connect to the network and needs data from the DHCP server to interact with the network.

A DHCP relay refers to any transmission control protocol/IP (TCP/IP) host that forwards DHCP messages between servers and clients. A DHCP relay plays an essential role, for instance, when a network consists of several subnetworks. In this case, a DHCP relay enables one DHCP server to provide the necessary information to all of the clients on both the primary network and subnet.

Security Considerations for Using DHCP

To ensure your DHCP servers do not present significant risk, there are a few DHCP security-related issues to keep in mind:

1.         A DHCP server can only provide a limited number of IP addresses. This means an attacker may be able to launch a denial-of-service (DoS) attack by requesting so many IP addresses, rendering essential devices unable to connect.

2.         It is also possible for an attacker to use a false DHCP server to provide fraudulent IP addresses to the clients on your network.

3.         Users that get an IP address also get the DNS address—meaning, it is possible they can obtain more data than they should from those servers. It is best to limit the access that people have to your network, as well as use firewalls and secure connection tunnels via virtual private networks (VPNs) .

Protection Against DHCP Starvation Attack

A DHCP starvation attack involves a malicious actor inundating a DHCP server with requests for IP addresses until it cannot provide any more. This puts the hacker in a position to deny requests from authorized network users, as well as set up an alternative DHCP connection that can pave the way for a man-in-the-middle (MITM) attack .

Best Practices for DHCP Deployment

To enable a smooth, effective DHCP deployment, there are a few best practices that you can follow including:

1. Avoid putting DHCP on your domain controller

Your domain controller should only be responsible for performing core functions, particularly managing your DNS. If you avoid putting DHCP on your domain controller, you can avoid overwhelming it with additional work. 

This enhances network security because it prevents those connecting to your guest Wi-Fi from having access to your domain controller. By preventing this interaction, you keep your attack surface small, especially because you deny a hacker that signs in to your guest Wi-Fi access to your domain controller. If they are able to access this sensitive system, they could hack your DNS.

2. Use DHCP failover

Like other kinds of failover , DHCP failover helps ensure you always have a DHCP server to share the essential information needed by hosts in your network. In the event the primary DHCP server goes down, the additional server will provide the DHCP information clients need.

3. Avoid using static IP addresses when possible

Deciding between DHCP vs static IP can be a challenging puzzle. What does DHCP stand for? Well, the “dynamic” element of the acronym is important when it comes to maintaining seamless network operations, particularly because it enables the system to change DHCP data as needed. A static IP address is one that does not change. Even though this may seem like a logical decision for devices you feel will always be connected to your network, it can cause problems. 

Suppose, for example, you have to replace that device with an identical but new one. This may require your IT team to manually assign an IP address to the device so it can connect with others in your network, which could take time. Of course, for some devices, such as routers and switches, you need a fixed IP address, primarily because they serve as “connection hubs,” and if their IP address continually changes, the network will not function smoothly.

‘Learn More about Static vs Dynamic IP ’

Reasons Why Enterprises Must Automate DHCP

It is important for enterprises to automate their DHCP system because it helps eliminate time-consuming manual work that could otherwise consume a lot of your IT team’s energy.

For example, there are a lot of problems, such as printers not connecting with the network or subnets not interfacing with the main network, that can result from DHCP-related issues. By automating your DHCP functions, the system can automatically prevent many of these issues.

Automated DHCP also makes it easier to scale your operations. Instead of having to bring in more people to manually handle what an automated system could manage, you can invest your human resources in other growth-related tasks.

Frequently Asked Questions about DHCP

What is dhcp and why is it used.

Dynamic Host Configuration Protocol (DHCP) is a networking protocol for dynamically assigning IP addresses to each host on your organization's network. DHCP also assigns Domain Name System (DNS) addresses, subnet masks, and default gateways.

What are best practices for DHCP servers?

Some best practices for DHCP servers are to avoid putting DHCP on your domain controller, use DHCP failover, and avoid using static IP addresses when possible.

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DORA Process: DHCP’s Automatic IP Assignment Mechanism

Dora process in dhcp, are you familiar with the term dora.

NO, not Dora the Explorer. Although admittedly she was the first thing that came to mind the moment, I first heard of the DORA process.

In computer networking , DORA stands for.

• Acknowledge

DHCP uses this process to automatically assign IP addresses to client machines. If you are new to computer networking then you might be wondering what these terms mean, and why you should care. Luckily for you, I will break them down in the following section.

What is DHCP?

DHCP (Dynamic Host Configuration Protocol) is a network protocol that automatically assigns IP address and other network configuration parameters to devices on a network.

DHCP follows a 4-step process known as DORA to dynamically allocate IP addresses to devices. It centrally manages the assignment of unique IP addresses, eliminating the need for manual configuration on each device, simplifies network administration and ensures efficient communication.

What is the DORA process?

Every device requires a unique IP address to communicate. These IP addresses can be assigned either manually as static Ips or dynamically through the Dynamic host Configuration Protocol (DHCP).

The DHCP process for dynamic IP address assignment follows the DORA sequence.

• Discover: The client device sends a DHCP Discover message to request an IP address.

• Offer: The DHCP server responds with a DHCP Offer message, proposing an available IP address.

• Request: The client accepts the offered IP address by sending a DHCP Request message.

• Acknowledge: Finally, the DHCP server confirms the IP address assignment by sending a DHCP Acknowledgement message.

The client-server DORA process allows DHCP to efficiently manage the dynamic allocation of unique IP addresses across a network, rather than requiring manual configuration.

Why is the DORA process necessary?

• Dynamic IP assignment

• Automated configuration

• Ensuring unique Ips

• Reducing overhead• Supporting mobility

In this Blog, we have summarized the key steps in the DHCP process for assigning IP addresses to client devices. The DORA sequence: Discover, Offer, Request, and Acknowledge, is the fundamental mechanism that enables a DHCP server to automatically configure network settings for connected devices. This automation provided by DHCP’s process is essential for efficiently managing modern, complex networks, where manually configuring every device would be impractical. By understanding this core DHCP functionality, network administrators can leverage its convenience and efficiency to simplify network management.

FAQs Related to DORA Process:

1. what is the purpose of the dora process.

It is a mechanism used by DHCP to automatically assign unique IP addresses to devices on a network.

2. Is the DORA process only used for dynamic IP address assignment?

Yes, the DORA process is specific to the dynamic IP address assignment done by DHCP. Static IP addresses are assigned manually without going through this process.

3. Is DHCP OFFER a Unicast or Multicast?

DHCP OFFER is a layer3 broadcast as the server doesn’t know clients’ IP addresses. It only knows the client’s MAC address.

4. What is DHCP port number?

DHCP uses UDP port number 67 for the destination server and UDP port number 68 for the client.

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Dynamic Host Configuration Protocol (DHCP): Explained

DHCP the protocol that enables automatic assignment of IP addresses to hosts on a network

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For a device to be able to communicate with other devices (on LAN and Internet) it needs to have an IP Address. IP addresses are unique numeric identifiers that are used to identify devices on a network.

IP addresses based on how they are assigned are classified into two types:

Static IP addresses are assigned manually to hosts by the network administrator. While assigning IPs manually on a small network is achievable, it is practically impossible to do so on a network that contains hundreds of devices. The network administrator also needs to ensure that the IP addresses that are being configured are unique and they do not overlap with other hosts.

Dynamic IP addresses are assigned automatically to hosts on the network by the DHCP server. The DHCP server provides IP addresses from its pool of IP addresses. Any additional network configuration that could be required by the host can also be set using DHCP.

The process of assigning static IP addresses does not scale well on large networks. An automated method to assign IP addresses was required. To enable rapid IP address deployment DHCP was created.

DHCP Protocol

DHCP stands for Dynamic Host Configuration Protocol. DHCP enables the automatic assignment of unique IP addresses to hosts on the network. It can also automatically set up other network-related details like Subnet Mask, Default Gateway and DNS address for the host. DHCP is responsible for network-related configuration management and automatic assignment of IP addresses for devices on a network.

DHCP Architecture

DHCP utilizes the client-server model. The DHCP client is pre-installed on all devices that can connect to the internet (laptops, printers, VoIP phones). DHCP uses UDP for communication. The client runs on port 68 while the server runs on port 67. The DHCP server can be installed on a dedicated server (commonly found on Enterprise networks). It is also available as a built-in service on router/SOHO devices (Home network).

DHCP server can also be set up behind a relay agent (Fig. 1 & 3). The relay agent is a device that forwards DHCP requests to the DHCP server. Some routers support being set up as DHCP relay agents as well. DHCP packets are always broadcasted over the network. Broadcast packets cannot travel from one network to another (cannot cross the router). By utilizing a relay agent we can overcome this limitation. Using the relay agent setup a single DHCP server can manage the assignment of IP addresses for hosts on multiple networks (Fig. 1).

The IP addresses that are assigned to hosts are assigned from the DHCP scope. The DHCP scope is the range of IP addresses that have been configured on the DHCP server to be handed out to devices on the network. DHCP scope is also referred to as the IP Address Pool.

The IP addresses that are assigned to hosts by the DHCP server are not permanent. They are leased by the host from the DHCP server for a short duration.

Consider a network with a DHCP server and three hosts. The DHCP scope has been configured to contain three IP addresses (10.0.1.2, 10.0.1.3 and 10.0.1.4). Instead of leasing out IP addresses the DHCP server permanently assigns IP addresses to devices. When there are only three hosts on the network everything functions normally.

Now assume one of the devices on the network had to be taken offline and in its place a new host was introduced into the network.

The DHCP server will not be able to assign an IP address to the new device as its scope does not have any free IP Address. If the device that was taken offline had freed its IP Address the new device would have received an IP Address. Using permanent IP addresses can cause the DHCP server IP address pool to get depleted. To prevent running into this situation DHCP servers always lease IP addresses.

DHCP server keeps track of the IP addresses that it has leased along with the lease period of the address. Before the lease period of an IP address expires the host can make a lease renewal request to the DHCP server to continue using the IP Address. If the lease period for an IP address expires and the host that was using the address does not make a lease renewal request the IP address is taken away from the host and added back into the IP address pool. Similarly, when a host is rebooted or when the network interface of the host is restarted/rebooted the IP address is taken away.

Reservations

If we want a host to be assigned the same IP address every time, we can create a reservation for that IP address in the DHCP server. A reservation will prevent the IP address from being leased out to other devices. Reservations are mapped using the MAC address of the device. Reservations are generally created for special devices on the network like printers, routers, and servers.

DORA Process

The DORA process is used to assign an IP Address to a host that does not have an IP Address.

Step1: DHCP Discover

When a host connects to a network for the first time it will not have an IP address. Its address will show up as 0.0.0.0 . It will also not have details like Subnet Mask, Default Gateway and DNS address configured. The host sends out a DHCP Discover broadcast message to locate the DHCP server on the network.

If the device was connected to the network previously, in the broadcast message sent to the DHCP server an extra field is included. This field contains the IP address that was previously assigned to the host. The host includes this field to find out from the DHCP server if it can be assigned the same IP address again.

Step 2: DHCP Offer

The DHCP server sends an offer for an IP to the requesting client. If more than one offer is received by the host, the host will choose the first offer that it receives.

A host receives more than one offer when there are multiple DHCP servers present on the network.

Step 3: DHCP Request

On receiving the DHCP offer message the host broadcasts an ARP packet on the network. This is done to ensure that no other host on the network is using the IP Address that was offered by the DHCP server. Only when no response for the ARP packet is received does the host reply to the message from the DHCP server indicating it would like to use the IP Address.

If the host receives a response for the ARP request it indicates that the host has been offered a duplicate IP address. In this scenario, the client declines the offer using the DHCP Decline message and starts the DORA process all over again.

Even though the DHCP server keeps track of all the addresses that it hands out, it is still possible for IP address collisions to occur. The network could contain devices that use static IP addresses that fall in the same range as the DHCP server IP pool. The DHCP server could crash which would result in the DHCP IP address mapping getting cleared. It’s also possible that the IP address has already been given to a device on the network by another DHCP server running on the same network. To counter these edge cases the device being offered the IP address makes an ARP request to ensure that no device on the network is using the same IP address.

Step 4: DHCP Acknowledgment

The DHCP server then sends the IP Address to the client along with other network properties that are needed by the host to communicate on the network and access the internet.

If the DHCP server is set up behind a relay agent, the request messages from the client are sent to the relay agent as a broadcast, the relay agent then forwards the message as an unicast packet to the DHCP server. Similarly, the responses from the DHCP server are sent to the relay agent as an Unicast message and the relay agent then broadcasts the message on the interface on which it received the original request.

Renewal Process

Both the packet used in the renewal process is sent using Unicast.

Step 1: DHCP Request

When half of the lease period has passed the host initiates a DHCP renewal request. The host sends its current IP address along with its network configuration parameters to the DHCP Server.

Step 2: DHCP Acknowledgment

If the DHCP server accepts the renewal request it sends back an acknowledgment packet to the host. If the DHCP server does not accept the Renewal request the host can continue using the IP address until the lease period is active. If the lease period expires and the host still wants to access the internet it has to perform the entire DORA process to get a new IP address.

Release Process

When the host is done using the IP address it can release its IP address using the DHCP Release message. In this message, the IP address that needs to be reclaimed by the DHCP server is specified. Unicast communication is used for sending the packet.

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• Automatic allocation —The DHCP server assigns a permanent IP address to a client from its IP Pools . On the firewall, a Lease specified as Unlimited means the allocation is permanent.
• Dynamic allocation —The DHCP server assigns a reusable IP address from IP Pools of addresses to a client for a maximum period of time, known as a lease . This method of address allocation is useful when the customer has a limited number of IP addresses; they can be assigned to clients who need only temporary access to the network. See the DHCP Leases section.
• It is an address from the IP Pools . You may configure multiple reserved addresses.
• If you configure no Reserved Address , the clients of the server will receive new DHCP assignments from the pool when their leases expire or if they reboot, etc. (unless you specified that a Lease is Unlimited ).
• If you allocate all of the addresses in the IP Pools as a Reserved Address , there are no dynamic addresses free to assign to the next DHCP client requesting an address.
• You may configure a Reserved Address without configuring a MAC Address . In this case, the DHCP server will not assign the Reserved Address to any device. You might reserve a few addresses from the pool and statically assign them to a fax and printer, for example, without using DHCP.

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• Network infrastructure

DHCP (Dynamic Host Configuration Protocol)

• Alexander S. Gillis, Technical Writer and Editor

What is DHCP (Dynamic Host Configuration Protocol)?

DHCP (Dynamic Host Configuration Protocol) is a network management protocol used to dynamically assign an IP address to any device, or  node , on a network so it can communicate using IP. DHCP automates and centrally manages these configurations rather than requiring network administrators to manually assign IP addresses to all network devices. DHCP can be implemented on small local networks, as well as large enterprise networks.

DHCP assigns new IP addresses in each location when devices are moved from place to place, which means network administrators do not have to manually configure each device with a valid IP address or reconfigure the device with a new IP address if it moves to a new location on the network.

Versions of DHCP are available for use in IP version 4 ( IPv4 ) and IP version 6 ( IPv6 ). IPv6 became an industry standard in 2017 -- nearly 20 years after its specifications were first published. While the adoption rate of IPv6 was slow, more than 29% of Google users were making inquiries using IPv6 by July 2019.

How DHCP works

DHCP runs at the application layer of the TCP/IP stack. It dynamically assigns IP addresses to DHCP clients and allocates TCP/IP configuration information to DHCP clients. This information includes  subnet  mask information, default gateway IP addresses and domain name system ( DNS ) addresses.

DHCP is a client-server protocol in which servers manage a pool of unique IP addresses, as well as information about client configuration parameters. The servers then assign addresses out of those address pools. DHCP-enabled clients send a request to the DHCP server whenever they connect to a network.

Clients configured with DHCP broadcast a request to the DHCP server and request network configuration information for the local network to which they're attached. A client typically broadcasts a query for this information immediately after booting up. The DHCP server responds to the client request by providing IP configuration information previously specified by a network administrator. This includes a specific IP address, as well as a time period -- also called a  lease  -- for which the allocation is valid.

When refreshing an address assignment, a DHCP client requests the same parameters, but the DHCP server may assign a new IP address based on policies set by administrators. DHCP clients can also be configured on an Ethernet interface.

A DHCP server manages a record of all the IP addresses it allocates to network nodes. If a node is relocated in the network, the server identifies it using its media access control ( MAC ) address, which prevents the accidental configuration of multiple devices with the same IP address. Configuring a DHCP server also requires the creation of a configuration file, which stores network information for clients.

DHCP is not a routable protocol, nor is it a secure one. DHCP is limited to a specific  local area network , which means a single DHCP server per LAN is adequate -- or two servers for use in case of a failover. Larger networks might have a wide area network ( WAN ) that contains multiple individual locations. Depending on the connections between these points and the number of clients in each location, multiple DHCP servers can be set up to handle the distribution of addresses.

If network administrators want a DHCP server to provide addressing to multiple subnets on a given network, they must configure DHCP relay services located on interconnecting routers that DHCP requests have to cross. These agents relay messages between DHCP clients and servers located on different subnets.

DHCP lacks any built-in mechanism that enables clients and servers to authenticate each other. Both are vulnerable to deception -- one computer pretending to be another -- and to attack, where rogue clients can exhaust a DHCP server's IP address pool.

When managing many DHCP servers or DHCP servers in a WAN, users can work with a command line. Users should also be aware that starting, stopping and restarting affects the running of the daemon.

Components of DHCP

DHCP is made up of numerous components, such as the DHCP server, client and relay.

The DHCP server -- typically either a server or router -- is a networked device that runs on the DHCP service. The DHCP server holds IP addresses, as well as related information pertaining to configuration.

The DHCP client is a device -- such as a computer or phone -- that connects to a network and communicates with a DHCP server.

The DHCP relay manages requests between DHCP clients and servers. Typically, relays are used when an organization has to handle large or complex networks.

Other components include the IP address pool, subnet, lease and DHCP communications protocol.

Static vs. dynamic DHCP leases

With dynamic DHCP, a client does not own the IP address assigned to it but instead  leases  it for a period of time. Each time a device with a dynamic IP address is powered up, it must communicate with the DHCP server to lease another IP address. Wireless devices are examples of clients that are assigned dynamic IP addresses when they connect to a network.

On the other hand, static devices -- such as web servers and switches -- are assigned permanent IP addresses.

Under a dynamic DHCP setup, a client might also have to perform certain activities that lead to terminating its IP address and then reconnecting to the network using a different IP address. DHCP lease times can vary depending on how long a user is likely to need an internet connection at a particular location. Devices release their IP addresses when their DHCP leases expire and then request a renewal from the DHCP server if they are staying online. The DHCP server may assign a new address rather than renewing an old one.

The typical dynamic DHCP lease cycle is as follows:

• A client acquires an IP address lease through the allocation process of requesting one from the DHCP server.
• If a client already has an IP address from an existing lease, it needs to refresh its IP address when it reboots after being shut down and contact the DHCP server to have an IP address reallocated.
• Once a lease is active, the client is bound to the lease and to the address.
• Once the lease has expired, a client contacts the server that initially granted the lease to renew it so it can keep using its IP address.
• If a client is moving to a different network, its dynamic IP address is terminated, and it requests a new IP address from the DHCP server of the new network.

DHCP uses and functions

DHCP is used to distribute IP addresses within a network and to configure the proper subnet mask, default gateway and DNS server information on the device.

DHCP, including Request for Comments (RFC) 8415 -- the draft version released in November 2018 -- can also be used by ordinary electronic devices whose manufacturers want them to be part of the internet of things ( IoT ). DHCP is one method of connecting devices -- such as refrigerators and lawn sprinkler systems -- to the internet using a Manufacturer Usage Description (MUD), suggested by the Internet Engineering Task Force (IETF).

Pros and cons of DHCP

DHCP makes it easier for network administrators to add or move devices within a network, whether it be a LAN or WAN. But DHCP is not inherently secure, and if malicious actors access the DHCP server, they can wreak havoc. Also, if the DHCP server does not have a backup and the server fails, so do the devices served by it.

DHCP security

One of the key vulnerabilities of DHCP has been the use of so-called man in the middle ( MitM ) attacks, in which an attacker secretly intercepts and relays messages between two parties who believe they are communicating directly with each other.

DHCP servers have also been the subject of multiple memory corruption vulnerabilities. In these, attackers have targeted the Windows DHCP Server service. When successful, the attacks can lead to a full compromise of Microsoft Active Directory (AD). One such vulnerability, patched by Microsoft, was the Common Vulnerabilities and Exposures (CVE)-2019-0725 Windows DHCP Server Remote Code Execution (RCE) Vulnerability.

History of DHCP

DHCP is an extension of a 1985 network IP management protocol, Bootstrap Protocol ( BOOTP ). DHCP is more advanced, and DHCP servers can handle BOOTP client requests if any BOOTP clients exist on a network segment.

Using one central BOOTP server to serve hosts on many IP subnets, BOOTP introduced the concept of a relay agent that enabled BOOTP packets to be forwarded across networks. BOOTP required a manual process to add configuration information for each client, however, and did not provide a mechanism for reclaiming IP addresses no longer in use.

Editor's note: This definition was republished to improve reader experience.

Continue Reading About DHCP (Dynamic Host Configuration Protocol)

• DHCP client configuration for Linux, Windows and macOS
• 12 common network protocols and their functions explained
• Static IP vs. dynamic IP addresses: What's the difference?
• Brief introduction: DHCP and DNS

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Step-by-Step: Configure DHCP Using Policy-based Assignment

Updated: May 27, 2016

Applies To: Windows Server 2012, Windows Server 2012 R2

The Dynamic Host Configuration Protocol (DHCP) server role in Windows Server 2012 introduced a new policy based IP address assignment feature. Policy based assignment (PBA) allows an administrator to group DHCP clients by specific attributes based on fields contained in the DHCP client request packet. This feature allows for targeted administration and greater control of configuration parameters delivered to network devices.

In this guide

This guide provides step-by-step instructions for deploying DHCP policy based assignment in a test lab using one server computer and two client computers. Software and hardware requirements are provided, as well as an overview of DHCP policy based assignment.

The following instructions are for configuring a test lab using the minimum number of computers. Individual computers are needed to separate the services provided on the network and to clearly show the desired functionality. This configuration is neither designed to reflect best practices nor does it reflect a desired or recommended configuration for a production network. The configuration, including IP addresses and all other configuration parameters, is designed only to work on a separate test lab network.

DHCP policy based assignment overview

With a DHCP server running Windows Server 2012 or Windows Server 2012 R2, administrators can define an address assignment policy at the server level or scope level. A policy contains a set of conditions to evaluate when processing client requests. Policy based assignment enables flexibility for some common scenarios, including:

Multiple device types : A network includes many different DHCP client devices, such as printers, IP phones, and desktops. Administrators need the ability to classify these devices using different IP address ranges. This enables router policies and quality of service (QoS) based on IP address range policies to control network access or traffic. For example, you can add a vendor class of “Hewlett-Packard JetDirect” or Cisco Systems, Inc. IP Phone CP-7940G and configure printer and IP-phone policies to assign a specific IP address range to these devices.

Multiple roles : A network includes different types of computers, such as laptops, desktops, and servers in the same subnet. Depending on the type of client, the administrator might wish to provide different lease duration settings. All the wireless clients that connect via a specific relay agent can be assigned a four-hour lease duration. DNS dynamic update protocol can be disabled for clients matching this policy. Similarly, a server policy can be created using a list of server MAC addresses. Servers can be assigned a 12-day lease duration

Virtualization : A data center network employs virtualization for different workloads and applications. Virtual machines are added and removed dynamically depending upon load requirements at a given time. An administrator wishing to route traffic on the network differently for VMs can create a policy based on MAC address prefix to assign a short lease duration, specific IP address range, and different default gateway.

The following fields in the DHCP client request are available when defining policies.

Vendor Class

MAC address

Client Identifier

Relay Agent Information

Policy settings and evaluation

Policy settings can be of three types.

IP address range : The IP address range within a scope from which to assign an IP address to a client. A server level policy cannot have a setting for an IP address range.

Standard DHCP options : One or more standard DHCP options to send to a client in the response based on the options requested by the client in the parameter request list.

Vendor specific DHCP options : One or more vendor specific DHCP options to send to the client based on the vendor class field in the client request.

The DHCP server evaluates policies sequentially according to an assigned processing order. The DHCP administrator assigns the processing order to the policies. If policies exist at the server and scope levels, the server applies both sets of policies and evaluates the scope policies before the server policies. The processing order for a scope level policy defines the order of evaluation within the scope. If there are no policies defined at the scope level, the policies at the server level apply to the scope.

Address assignment

The DHCP server determines the scope to which a DHCP client belongs based on the gateway IP address of the relay agent or the interface of the DHCP server on which it receives the DHCP client packet. Once the server determines the client scope, the server evaluates the DHCP packet against the policies applicable for the scope in the processing order specified. The policies applicable at a scope are those configured at the scope and those inherited from the server. A single client request can match multiple policies.

If a client request matches the conditions of a policy for which a specific IP address range is associated, the server will assign the first free IP address from the range as determined by the rule. If a policy is associated with multiple address ranges, the server will assign IP addresses by first attempting to assign an IP from the lowest address range. If no IP addresses are available to use from the lower address range, the server will then look for a free IP address from the higher address ranges. If no IP addresses are free from any of the address ranges associated with the policy, the server will process the next matched policy as defined by the processing order.

If none of the matched policies has a free IP address, the server will drop the client packet and log an event. If a DHCP client packet does not match any of the policies applicable for the scope, or none of the matched policies for a client packet is associated with an IP address range, the server will lease the client an IP address from the IP address range configured for the scope exclusive of any policy-specific IP address ranges.

Option assignment

A DHCP client uses the parameter request list field in a DHCP packet to request a list of standard options from the server. The option assignment processing for a client is similar to that of IP address assignment. The DHCP server evaluates the fields in the client request against each policy applicable for the scope in the processing order specified. If the client request matches the conditions of any of the policies applicable for the scope, and its settings include specific options, the server returns these options to the client. If multiple policies match the client request, the server returns the sum of the options specified for each of the matched policies. The DHCP server sends vendor class options to the client based on the vendor class contained in the DHCP client request.

Scenario overview

This test lab demonstrates new DHCP functionality in Windows Server 2012 or Windows Server 2012 R2. One server computer and two client computers are used. See the following figure.

Hardware and software requirements

One server computer and two client computers are required to complete the test lab.

The following are required components of the test lab:

The product disc or other installation media for Windows Server 2012 or Windows Server 2012 R2.

One computer that meets the minimum hardware requirements for Windows Server 2012 or Windows Server 2012 R2.

At least one DHCP client computer is required.

The lab uses two computers running Windows® 8. If only one client computer is available, or clients are not running Windows 8, you must alter some of the procedures in the test lab accordingly.

Steps for configuring the test lab

The following procedures are used to configure computers for the demonstration portion of the test lab:

Configure DHCP1 : DHCP1 is a domain controller, DNS server, and DHCP server for the contoso.com Active Directory domain.

Configure Client1 : Client1 is a DHCP client computer.

Configure Client2 : Client2 is a DHCP client computer.

Configure DHCP1

DHCP1 is a computer running Windows Server 2012 or Windows Server 2012 R2, providing the following services:

A domain controller for the contoso.com Active Directory domain.

An authoritative DNS server for the contoso.com DNS zone.

A DHCP server.

Initial configuration of DHCP1 consists of the following steps:

Install the operating system and configure TCP/IP on DHCP1

Install ad ds, dns server, and dhcp server, create a domain administrator account, create a dhcp scope on dhcp1, to install the operating system and configure tcp/ip on dhcp1.

Start your computer using the Windows Server 2012 or Windows Server 2012 R2 product disc or other digital media.

When prompted, enter a product key, accept license terms, configure clock, language, and regional settings, and provide a password for the local Administrator account.

Press Ctrl+Alt+Delete and sign-in using the local Administrator account.

If you are prompted to enable Windows Error Reporting, click Accept .

Click Start , type ncpa.cpl , and then press ENTER . The Network Connections control panel will open.

The previous step demonstrates the functionality in Windows Server 2012 or Windows Server 2012 R2 that enables you to search and run applications, settings, and files by clicking Start and then typing a search term. You can also open the Network Connections control panel by clicking next to Ethernet in Server Manager using the Local Server view. For more information, see Common Management Tasks and Navigation in Windows Server 2012 ( https://go.microsoft.com/fwlink/p/?LinkId=242147 ).

In Network Connections , right-click Ethernet and then click Properties .

Double-click Internet Protocol Version 4 (TCP/IPv4) .

On the General tab, choose Use the following IP address .

Next to IP address type 10.0.0.1 and next to Subnet mask type 255.255.255.0 . It is not necessary to provide an entry next to Default gateway .

Next to Preferred DNS server , type 10.0.0.1 .

Click OK twice, and then close the Network Connections control panel.

DHCP1 will serve as a domain controller, DNS server, and DHCP server for the contoso.com Active Directory domain.

To configure DHCP1 as a domain controller, DNS server, and DHCP server

The Server Manager Dashboard is displayed by default. In the navigation pane, click Configure this local server .

Under PROPERTIES , click the name next to Computer name . The System Properties dialog box will open.

On the Computer Name tab, click Change and then type DHCP1 under Computer name .

Click OK twice, and then click Close .

When you are prompted to restart the computer, click Restart Now .

After restarting the computer, sign-in using the local Administrator account.

In Server Manager, under Configure this local server , click Add Roles and Features .

In the Add Roles and Features Wizard , click Next three times, and then on the Select server roles page select the Active Directory Domain Services checkbox.

When you are prompted to add required features, click Add Features .

Select the DHCP Server checkbox.

Select the DNS Server checkbox.

Click Next five times, and then click Install .

Wait for the installation process to complete, verify on the Installation progress page that Configuration required. Installation succeeded on DHCP1 is displayed, and then click Close .

Click the Notification flag and then click Promote this server to a domain controller . See the following example.

In the Active Directory Domain Services Configuration Wizard , on the Deployment Configuration page, choose Add a new forest and then next to Root domain name , type contoso.com .

Click Next , and then on the Domain Controller Options page, under Type the Directory Services Restore Mode (DSRM) password , type a password next to Password and Confirm password . Confirm that Domain Name System (DNS) server and Global Catalog (GC) are selected, and then click Next .

Click Next four times, verify that All prerequisite checks passed successfully is displayed, and then click Install .

The computer will restart automatically to complete the installation process.

Sign in using the local Administrator account.

A domain administrator account is required to configure settings in the test lab.

You can use the CONTOSO\Administrator account in this test lab and skip creation of a domain administrator account if desired. This account has domain administrator privileges, and other privileges. However, it is a best practice to disable or rename this account. For more information, see Active Directory Best Practices ( https://go.microsoft.com/fwlink/p/?LinkID=243071 ).

To create a domain administrator account

On the Server Manager menu bar, click Tools , and then click Active Directory Users and Computers .

In the Active Directory Users and Computers console tree, double-click contoso.com , right-click Users , point to New , and then click User .

In the New Object – User dialog box, type user1 under User logon name and next to Full name , then click Next .

Next to Password and Confirm password , type a password for the user1 account.

Clear the checkbox next to User must change password at next logon , select the Password never expires checkbox, click Next , and then click Finish .

Click the Users folder, and then double-click user1 and then click the Member Of tab.

Click Add , type domain admins under Enter the object names to select , click OK twice, and then close the Active Directory Users and Computers console.

Click Start , click Administrator , and then click Sign out .

Sign in to the computer using the user1 credentials. Click Other user and then type the user1 name and password.

Next, create a DHCP scope on DHCP1.

To create a DHCP scope on DHCP1

On the Server Manager menu bar, click Tools and then click DHCP . The DHCP console opens.

In the DHCP console tree, navigate to IPv4 . Right-click IPv4 and then click New Scope . The New Scope Wizard opens.

Click Next and then type a name for the new scope next to Name (ex: Contoso-scope1).

Click Next and then in IP Address Range , type 10.0.0.1 next to Start IP address , type 10.0.0.254 next to End IP address , and type 24 next to Length . The value of Subnet mask will change automatically to 255.255.255.0 .

Click Next , and then in Add Exclusions and Delay type 10.0.0.1 under Start IP address , type 10.0.0.10 under End IP address , and then click Add . This allows the first ten IP addresses in the 10.0.0.0/24 subnet to be used for static addressing of servers on the network.

Click Next and then in Lease Duration under Limited to enter 0 Days , 0 Hours , and 2 Minutes . This very short lease duration will simplify the DHCP demonstration.

Click Next three times, and then in Domain Name and DNS Servers , verify that the Parent domain is contoso.com and 10.0.0.1 is listed as the only DNS server.

Click Next twice, and then in Activate Scope select Yes, I want to activate this scope now .

Click Next , and then click Finish .

In the DHCP console tree, right-click dhcp1.contoso.com , and then click Authorize .

Refresh the view in the DHCP console and verify that DHCP1 is authorized and that the Contoso-scope1 is active.

Note: To review scopes on the current server using Windows PowerShell, right-click Windows PowerShell , click Run as Administrator , click Yes in the User Account Control alert that appears, and then type the following command at the Windows PowerShell prompt, and then press ENTER.

Configure Client1

Client1 is a computer running Windows® 8 that is acting as a DHCP client.

Configuration of Client1 consists of the following steps:

Install the operating system on Client1

Pin windows powershell to the taskbar.

During the demonstration portion of the test lab, Client1 will be used as a DHCP client.

To install the operating system on Client1

Start your computer using the Windows 8 product disc or other digital media.

When prompted, enter a product key and accept license terms.

When prompted to enter a computer name, type Client1 and click Next .

Click Use express settings .

On the Sign in to your PC page, click Don’t want to sign in with a Microsoft account and then click Local account .

Next to User name , type user1 , enter a password and password hint, and then click Finish .

The DHCP failover demonstration on Client1 makes use of Windows PowerShell to verify DHCP lease information. To make Windows PowerShell more easily accessible, it will be pinned to the taskbar.

To pin Windows PowerShell to the taskbar

The Start menu is displayed by default. If Start is not displayed, move the mouse cursor to the lower left corner of the screen until Start is displayed, and then click Start .

Type powershell and then under Results for “powershell” right-click Windows PowerShell and then click Pin to taskbar .Confirm that Windows PowerShell is pinned to the taskbar.

Client1 can also be joined to the contoso.com domain; however this is not required to complete the test lab.

Configure Client2

Client2 is a computer running Windows 8 that is acting as a DHCP client.

Configuration of Client2 is nearly identical to Client1. To configure Client2, repeat the identical procedures used to configure Client1, except when you enter a computer name, type Client2 instead of Client1.

DHCP policy based assignment demonstration

For the DHCP policy based assignment demonstration portion of the test lab, a MAC address based policy will be configured to assign unique DHCP options and IP address ranges to Client1 and Client2.

A demonstration of DHCP policy based assignment on Windows Server 2012 or Windows Server 2012 R2 consists of the following procedures:

Determine MAC addresses

Create policies, demonstrate policies.

Unique MAC addresses on Client1 and Client2 will be used to match different DHCP policies.

To determine MAC addresses

On DHCP1, open the DHCP console and navigate to IPv4\Scope [10.0.0.0] Contoso-scope1\Address Leases .

Click Address Leases and then in the details pane write down the MAC addresses listed for Client1 and Client2 under Unique ID .

The DHCP Policy Configuration Wizard will be used to create a unique policy for Client1 and another policy for Client2. A policy configured for an individual computer is not typical and is only configured for demonstration purposes. On a corporate network, you can use wildcards and other conditions to match multiple DHCP client devices.

To create policies

In the DHCP console, under Scope , right-click Policies and then click New Policy .

Ensure that you select the Policy folder under the Scope folder. This is the scope-level folder. The other Policies folder is for server-level policies and if you create a policy there you will not be able to create the IP address range policy for this exercise.

Next to Policy Name , type Client1 Policy , and then click Next .

On the Configure Conditions for the policy page, click Add .

In the Add/Edit Condition dialog box, choose MAC Address next to Criteria , type the MAC address for Client1 next to Value (001DB7A63D in this example), and then click Add , then click OK .

Click Next , and then in Configure settings for the policy , type 10.0.0.100 next to Start IP address and type 10.0.0.199 next to End IP address .

Click Next , and then under Available Options , select 003 Router , type 10.0.0.7 under IP address , and click Add .

Repeat the previous steps for Client2 using the following conditions, IP address ranges, and options:

Policy Name : Client2 Policy

Condition : MAC Address equals (in this example) 00155DB7A63E.

Start IP address : 10.0.0.200

End IP address : 10.0.0.254

003 Router : 10.0.0.8

Next, review the effect that these policies have on the IP address configuration of Client1 and Client2.

To demonstrate policies

In the details pane, under Policy Name , right-click one of the two policies you just created.

Note that you can move the policy up or down in the processing order, delete the policy, or disable the policy.

Click Properties .

Review the available parameters that you can edit on the General , Conditions , IP Address Range , Options , and DNS tabs.

Click OK , and then on Client1 type ipconfig /all at the Windows PowerShell prompt.

Client1 has been assigned the first IP address in the 10.0.0.100 – 10.0.0.199 range, and a default gateway of 10.0.0.7, as determined by the policy based assignment.

If the IP address hasn't changed yet, you can type ipconfig /release and then ipconfig /renew to get a new lease.

Repeat the previous step on Client2.

Client2 has been assigned the first IP address in the 10.0.0.200 – 10.0.0.254 range, and a default gateway of 10.0.0.8.

Policy based assignment in Windows Server 2012 or Windows Server 2012 R2 DHCP allows you to create simple yet powerful rules to administer DHCP on your network.

Additional resources

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Assigning a fixed IP address to a machine in a DHCP network

I want to assign a fixed private IP address to a server so that local computers can always access it.

Currently, the DHCP address of the server is something like 192.168.1.66 .

Should I simply assign the server this same IP as fixed and configure the router so that it will exclude this IP from the ones available for DHCP? Or are there some ranges of IP that are traditionally reserved for static addresses?

My beginner's question doesn't relate to commands but to general principles and good practices.

Practical case (Edit 1 of 2)

Thank you for the many good answers, especially the very detailed one from Liam.

I could access the router's configuration.

When booting any computer, it obtains its IPv4 address in DHCP.

The IP and the MAC addresses that I can see with the ipconfig all command in Windows match those in the list of connected devices that the router displays, so that I can confirm who is who.

The list of connected devices is something like

Things that I don't understand:

• Although all IP addresses are all obtained in DCHP, they are displayed as by the router as if they are static addresses.
• The router's setting "Enable DHCP on LAN" is set on "Off" but the IP addresses are obtained in DHCP.
• IP addresses attributed to the computers are outside of the very narrow DHCP range of 192.168.1.33 to 192.68.1.35

On any Windows computer connected in DCHP, ipconfig /all shows something like:

I'm missing something, but what?

Practical case (Edit 2 of 2)

Solution found.

For details, see my answer to Michal's comment at the bottom of this message.

I must admit that the way the router display things keeps some parts a mystery. The router seems to be using DHCP by default, but remembers the devices that were connected to it (probably using their mac address). It could be the reason why it lists the IPs as static although they're dynamic. There was also Cisco router at 192.168.1.4 which appeared for some business communications service, but I had no credentials to access it.

• There's no standard governing DHCP reservation ranges, but it would be kinda nice. –  LawrenceC Commented Apr 5, 2018 at 2:43
• Some routers allow you to define an IP for a chosen mac-address. Use that and DHCP will keep that address for your server. You could also set a DHCP range to e.g. 192.168.0.128 - 192.168.0.254 in a 192.168.0.1/255.255.255.0 network and set all static addresses on the "static" servers from within 192.168.0.2 - 192.168.0.127 range. –  Michal B. Commented Apr 5, 2018 at 7:29
• @Michal B.: I agree and did it meanwhile.: 1. Obtain the server's mac address. 2. Observe which IPs the router assigns to computers (eg. 192.168.0.50 to 192.168.1.70 ) 3. Start the server in DHCP. In the router panel, name it, basing on its mac address so that the router will remember it. 4. In the server switch IP from DHCP mode to manual and assign an IP that is beyond the ones that the router would assign to other devices (eg. 192.168.1.100 ). You can use nmtui and then edit the config file where you can replace PREFIX=32 by NETMASK=255.255.255.0 . 6. Restart the network service. –  OuzoPower Commented Apr 6, 2018 at 9:58

7 Answers 7

Determine the IP address that is assigned to your server and then go onto the DHCP and set a DHCP reservation for that server.

• 1 Reservations are essentially self-documenting. ++ –  mfinni Commented Apr 4, 2018 at 21:30
• 5 @mfinni ++ only works for programmers. -- for your comment :P –  Canadian Luke Commented Apr 4, 2018 at 23:59
• ..and yes he should also use a fixed IP, and label it. Document it. Maybe even reserve a range for this. In an enterprise using internal VPN it is common for these IP's to be hard coded in HOSTS files and SSH config files so it is a big deal when they suddenly change. –  mckenzm Commented Apr 5, 2018 at 1:30

DHCP services differ across many possible implementations, and there are no ranges of IP that are traditionally reserved for static addresses; it depends what is configured in your environment. I'll assume we're looking at a typical home / SOHO setup since you mention your router is providing the DHCP service.

Should I simply assign the server this same IP as fixed and configure the router so that it will exclude this IP from the ones available for DHCP?

I would say that is not best practice. Many consumer routers will not have the ability to exclude a single address from within the DHCP range of addresses for lease (known as a 'pool'). In addition, because DHCP is not aware that you have "fixed" the IP address at the server you run the risk of a conflict. You would normally either:

• set a reservation in DHCP configuration so that the server device is always allocated the same address by the DHCP service, or
• set the server device with a static address that is outside the pool of addresses allocated by the DHCP service.

To expand on these options:

Reservation in DHCP

If your router allows reservations, then the first, DHCP reservation option effectively achieves what you have planned. Note the significant difference: address assignment is still managed by the DHCP service, not "fixed" on the server. The server still requests a DHCP address, it just gets the same one every time.

Static IP address

If you prefer to set a static address, you should check your router's (default) configuration to determine the block of addresses used for DHCP leases. You will normally be able to see the configuration as a first address and last address, or first address and a maximum number of clients. Once you know this, you can pick a static address for your server.

An example would be: the router is set to allow a maximum of 128 DHCP clients with a first DHCP IP address of 192.168.1.32. Therefore a device could be assigned any address from 192.168.1.32 up to and including 192.168.1.159. Your router will use a static address outside this range (generally the first or last address .1 or .254) and you can now pick any other available address for your server.

It depends on the configuration of your DHCP service. Check the settings available to you for DHCP then either reserve an address in DHCP or pick a static address that is not used by DHCP - don't cross the streams.

• 1 Double++ on this. –  ivanivan Commented Apr 5, 2018 at 3:26
• 1 Thank you Liam for your very detailed and useful answer. After accessing the router's configuration, other issues arised that I added in the original message. –  OuzoPower Commented Apr 5, 2018 at 9:45
• @OuzoPower I'm new to responding here so don't have enough rep to comment on the question. Your update shows your router is not providing the DHCP service. The setting is off on the router, and your Windows ipconfig output shows the DHCP service is provided from a device at 192.168.1.5 . Do you have Pi-Hole or another similar device providing DHCP? That's where you'll find your DHCP configuration. NB: This also explains why the router shows the addresses as static and why DHCP assigned addresses are outside the range configured on the router. –  Liam Commented Apr 6, 2018 at 9:52
• @Liam: No Pi-Hole or similar thing as far as I know. Solution found: As I could not set DHCP ranges in the router but could register the mac address of the server in the router and then attribute to the server a fixed IP address that is far beyond the range that the router is naturally assigning to existing devices. Thanks to the registration of the server's mac address, the router keeps it in memory and shows the server as missing when thus is off. For details, see my answer to Michal B. in the original post. This solution seems working like a charm. –  OuzoPower Commented Apr 6, 2018 at 10:11
• @OuzoPower That approach may work in the short term but how do you know that the address you have picked is outside the DHCP range? Many DHCP systems pick addresses at random from the available pool. At some point you will need to know what your DHCP configuration actually is, rather than estimating by observation (!) otherwise you will experience some conflict. Your question asked about best practice. Here, best practice would be to know what system is handling DHCP for your LAN. I would start by visiting 192.168.1.5 or https://192.168.1.5/ for clues. –  Liam Commented Apr 6, 2018 at 10:48

It's not a bad habit to divide your subnet to DHCP pool range and static ranges, but of course you can do what JohnA wrote - use reservation for your server, but first case is IMHO clearer, because you are not messing up your DHCP server with unused extra settings (it could be confusing then for another admins who are not aware of that the server is static). if using DHCP pool + static pool, then just don't forget to add your static server to DNS (create A/AAAA record for it).

• I would like to add that the downside of DHCP reservations for servers is that if your DHCP environment is not sufficient fault tolerant, a DHCP server outage could cause all manner of problems. Monitor the DHCP closely and set leases that are long enough to be able respond to problems even after a long weekend. –  JohnA Commented Apr 5, 2018 at 2:06

I prefer to set my network devices, servers, printers, etc. that require a static IP address out of range of the DHCP pool. For example, xx.xx.xx.0 to xx.xx.xx.99 would be set aside for fixed IP assignments and xx.xx.xx.100 to xx.xx.xx.250 would be set as the DHCP pool.

• I like this approach as well. This way I can still access the servers even if the DHCP server takes the morning off or decides to start handing out invalid leases! –  ErikF Commented Apr 5, 2018 at 1:24
• Using isc-dhcp-server this is required (this is what my pi does, along with DNS caching, a fake domain for my LAN, and some traffic shaping for some wireless stuff). Unfortunately, I've seen browser based router config pages (both factory and replacement) that either require a reserved address to be in the dynamic pool... or out of it. –  ivanivan Commented Apr 5, 2018 at 3:30

In addition to the other answers I want to concentrate on the fact that your router configuration does not seem to fit the IP address configuration on your server.

Please have a look on the output of ipconfig /all:

IPv4 Address ........ 192.168.1.xx(prefered)

Default Gateway ........ 192.168.1.1 (= IP of the router)

DHCP server ............ 192.168.1.5

The clients in the network don't get the IP address from the router, but a different DHCP server in the network (192.168.1.5 instead of 192.168.1.1). You have to find this server and check it's configuration instead of the router's DHCP server config, which is seemingly only used for Wireless.

My router ( OpenWRT ) allows for static DHCP leases.

Static leases are used to assign fixed IP addresses and symbolic hostnames to DHCP clients.

So, you supply the MAC address of the server and it's desired IP address as a "static lease", and DHCP will always allocate the same IP. The client machine (the server in this case) requires no configuration changes and still picks up its IP address (the configured address) from DHCP.

Note that you can't assign a fixed IP addresses in 192.168 so that clients can "always access it" unless you also give each client a fixed IP address and subnet. Because if the clients use DHCP, then they get whatever subnect the DHCP server gives them, and if they use automatic addressing, then they won't be in a 192.168 subnet.

Once you realise that the system can't be easily perfected, you can see that your best options depend on what you are trying to do. Upnp is a common way of making devices visible. DNS is a common way of making devices visible. WINS is a common way of making devices visible. DHCP is a common way of making devices visible.

All of my printers have reservations: my printers aren't critical infrastructure, I want to be able to manage them, many of the clients use UPNP or mDNS for discovery anyway.

My gateway and DNS servers have fixed IP address in a reserved range: My DHCP server provides gateway and DNS addresses, and my DHCP server does not have the capacity to do dynamic discovery or DNS lookup.

None of my streaming devices have fixed or reserved IP values at all: if the network is so broken that DHCP and DNS aren't working, there is no way that the clients will be able to connect to fixed IP addresses anyway.

• This literally makes no sense. Are you asserting that you can’t mix static and dynamic in a /16? –  Gaius Commented Apr 5, 2018 at 12:59
• I have asserted that if you use static, you haven't gauaranteed that clients can "always access it"Not at all. I've just asserted that I've mixed static and dynamic in my setup. –  user165568 Commented Apr 6, 2018 at 9:46
• @Gaius I have asserted that if you use static, you haven't guaranteed that clients can "always access it". I'm sorry that doesn't make sense to you: it's one of the primary reasons the world moved away from static. I've also asserted that I've mixed static and dynamic in my setup: see: "none of my streaming devices have fixed or reserved" and "DNS servers have fixed IP": the DNS servers are indeed in the same subnet as the clients. –  user165568 Commented Apr 6, 2018 at 9:52
• Sorry, but I must admin not understanding most of your answer. As far as I know, DNS are domain name servers and are useful when you want to name servers, like when assigning domain names to web sites. As I don't need domain names, DNS appears me useless. Accessing the server is not an issue without DNS. See my answer to Michal B. in the original post for the solution that I found. –  OuzoPower Commented Apr 6, 2018 at 10:18

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dhcpv6 - stateful VS stateless, what is difference between it?

Can someone explain me, what is difference between DHCPv6 Stateful and Stateless? I was looking on the net and, surprisingly, I found only the remains of information but some general comparison or description of the differences between them did not find. If I'm correct:

• Stateful - Needs DHCPv6 server to get IP, DNS, etc.
• Stateless - DHCPv6 server is not needed. In this mode, host getting configuration (IP, DNS, etc.) from router ads.

2 Answers 2

A stateful address assignment involves someone keeping track of the State . Which is to say, some system exists that provides a log that certain IP addresses were assigned to certain MAC addresses. DHCP / DHCPv6 keeps track of such information.

A stateless address assignment does not keep track of what has or hasn't been assigned. It simply determines what address it should use on a particular network (to include possibly picking it at random after determining the prefix ) and uses a system like Duplicate Address Detection (DAD) to see if it inadvertently selected an address already in use.

In a Stateless assignment scenario, there is no server or device which keeps a running log of what IP addresses have been assigned and what IP addresses are remaining, available to be assigned. The mentality in a Stateless assignment scenario is: Pick an IP address. If it happens to be in use, pick another one .

TLDR: Stateful requires a DHCP server to have been configured to hand out addresses. While Stateless address assignment simply requires the Router/Default-Gateway to understand and implement RFC 4862

Your assertion is essentially correct.

• please provide an interfaces configuration examples, thank you. –  Akshay Commented Mar 17, 2023 at 9:39

Stateful configuration

Stateless configuration (also known as SLAAC-StateLess AutoConfiguration) The stateful version of DHCPv6 is pretty much the same as for IPv4. Our DHCPv6 server will assign IPv6 addresses to all DHCPv6 clients and it will keep track of the bindings. In short, the DHCPv6 servers knows exactly what IPv6 address has been assigned to what host.

Stateless configuration

Stateless works a bit different. The DHCPv6 server does not assign IPv6 addresses to the DHCPv6 clients, this is done through "autoconfiguration." The DHCPv6 server is only used to assign information that autoconfiguration doesn’t….stuff like a domain-name, multiple DNS servers and all the other options that DHCP has to offer.

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• Modem & Router

DHCP vs Static IP Addressing | What’s the Difference?

• January 12, 2024
• By Mounika D

In networking world, the choice between DHCP (Dynamic Host Configuration Protocol) and Static IP addressing is a fundamental consideration that shapes the efficiency, management, and reliability of a computer network. DHCP and Static IP represent two distinct approaches to assigning and managing IP addresses within a network, each with its own set of advantages and limitations. DHCP, as a dynamic and automated protocol, dynamically allocates IP addresses to devices as they connect to the network, streamlining the configuration process and enhancing scalability. In contrast, Static IP addressing involves the manual assignment of fixed IP addresses to devices, offering stability and control over network settings. This comparison between DHCP vs Static IP addressing is pivotal for network administrators and organizations, as it influences factors such as ease of management, security, and adaptability to network changes.

In this guide, we will look into the key differences, use cases, and many other things surrounding these two addressing methods.

Importance of IP Addressing in Computer Networks

IP addressing is a fundamental aspect of computer networks, serving as the backbone for communication between devices. Each device on a network requires a unique IP address to identify and differentiate itself from others. IP addresses are crucial for routing data packets across the network, ensuring that information reaches the intended destination accurately. They also play a pivotal role in defining the structure of a network by enabling devices to belong to specific subnets.

Proper IP addressing is essential for the efficient functioning of various network services, such as file sharing, printing, and internet connectivity. DHCP and static IP addressing represent two approaches to managing this critical aspect of network configuration, each with its own set of advantages and considerations based on the specific needs of the network and its devices.

Brief Overview of DHCP and Static IP Addressing

Dynamic Host Configuration Protocol, commonly known as DHCP, is a network protocol widely used for automated IP address configuration within a network. Its primary function is to dynamically assign IP addresses and other network configuration information to devices as they connect to the network. DHCP operates on a client-server model, where a central DHCP server manages a pool of IP addresses and leases them to devices for a specific duration.

This dynamic allocation of IP addresses helps streamline the network administration process by eliminating the need for manual configuration on individual devices. DHCP not only assigns IP addresses but also provides information like subnet mask, default gateway, and DNS server addresses, facilitating seamless communication within the network.

In contrast to DHCP, Static IP addresses are manually assigned to devices within a network. A static IP address remains fixed and does not change unless modified manually by the network administrator. When a device is configured with a static IP, it retains the same address every time it connects to the network. This method is particularly useful for devices that require a consistent and unchanging network presence, such as servers, routers, and network printers.

Unlike DHCP, where addresses are dynamically assigned, static IP addresses offer stability and predictability in network configurations. However, this approach demands more hands-on management, as each device needs individual attention for assigning and maintaining its static IP.

What is DHCP?

Dynamic Host Configuration Protocol (DHCP) is a networking protocol that plays a pivotal role in simplifying the process of assigning and managing IP addresses within a computer network. The primary purpose of DHCP is to automate the configuration of network devices by dynamically assigning IP addresses and providing essential network configuration information. This eliminates the need for manual intervention, making it a convenient and efficient solution for both small and large-scale networks.

Automatic IP Address Assignment

One of the key functionalities of DHCP is its ability to automatically assign IP addresses to devices when they join the network. When a device, known as a DHCP client, connects to the network, it sends a request to the DHCP server for an IP address. The DHCP server then dynamically allocates an available IP address from its predefined pool and leases it to the requesting device for a specific duration. This dynamic allocation ensures that IP addresses are utilized efficiently and avoids conflicts that may arise from manual assignment.

Dynamic Allocation of Network Configuration

Beyond IP address assignment, DHCP dynamically allocates additional network configuration parameters to the connected devices. These parameters include subnet masks, default gateways, and DNS server addresses. This dynamic allocation ensures that devices have the necessary information to communicate effectively within the network. It also enables flexibility in network configuration, allowing changes to be implemented centrally on the DHCP server and propagated to all connected devices without manual intervention.

Advantages of DHCP

Scalability.

DHCP provides a scalable solution for networks of varying sizes. As the network expands or contracts, DHCP can efficiently manage the allocation of IP addresses without requiring manual adjustments on each device. This scalability is particularly valuable in dynamic environments where the number of connected devices may change frequently.

Centralized Management

DHCP centralizes the management of IP addresses and network configurations, placing control in the hands of a designated DHCP server. This centralized approach streamlines administration tasks, reducing the complexity associated with individually configuring each device. Administrators can implement changes, updates, or modifications from a single point, ensuring consistency and accuracy across the network.

Simplified Network Administration

DHCP significantly simplifies network administration by automating the IP address assignment process. This automation reduces the risk of human errors associated with manual configurations, saving time and effort for administrators. Additionally, DHCP logs and records lease information, aiding in the monitoring and troubleshooting of network issues. Overall, the automated nature of DHCP contributes to a more efficient and manageable network infrastructure.

What is Static IP Addressing?

A Static IP (Internet Protocol) address is a fixed and unchanging numerical label assigned to a device within a computer network. Unlike Dynamic Host Configuration Protocol (DHCP), where IP addresses are automatically assigned by a server, static IP addresses are manually configured and remain constant over time. The purpose of using static IP addresses is to provide a stable and predictable identity for certain devices within the network, allowing for consistent communication and easier management of critical network components.

Manual Assignment of IP Addresses

In the case of static IP addresses, the assignment is done manually by a network administrator. Each device that requires a static IP is configured with a specific address, and this assignment is typically done through the device’s operating system settings or by configuring the network infrastructure, such as routers or switches. This manual approach allows for precise control over the IP address assignment, making it a suitable choice for devices that need to maintain a fixed network presence.

Fixed Network Configuration

Static IP addresses are associated with a fixed network configuration, meaning that the assigned IP does not change unless modified intentionally by the network administrator. This fixed nature ensures that the device always has the same address when connecting to the network, providing stability and predictability in network communication. Unlike DHCP, where IP addresses may change dynamically, static IP addresses are particularly advantageous for devices that require constant accessibility and consistent identification, such as servers or network appliances.

Advantages of Static IP

Control over ip address assignment.

One of the primary advantages of using static IP addresses is the control it affords network administrators. With manual assignment, administrators have precise control over which IP addresses are allocated to specific devices. This control is beneficial in situations where maintaining a consistent and known IP address for certain devices is crucial for operational requirements, security, or network configuration.

Stability and Predictability

Static IP addresses contribute to network stability and predictability. Since the assigned IP addresses do not change automatically, devices with static IPs maintain a constant network identity. This stability is particularly advantageous for servers, network printers, and other critical infrastructure components that require a reliable and unchanging network presence for seamless operation.

Better for Servers and Network Devices

Static IP addresses are often preferred for servers and network devices due to their unchanging nature. Servers, for example, need to be easily accessible for other devices on the network, and a static IP ensures consistent connectivity. Additionally, network devices such as routers, switches, and network-attached storage (NAS) devices benefit from static IPs as they play central roles in network operations and require a reliable and fixed network presence for effective communication.

DHCP vs Static IP Addressing Comparison

Configuration process.

DHCP has an automated and dynamic configuration process. When a device joins the network, it sends a request to the DHCP server, which dynamically assigns an available IP address and provides additional network configuration information. This automated process eliminates the need for manual intervention, making it efficient for large networks where managing individual device configurations manually would be impractical.

In contrast, static IP configuration involves a manual and fixed process. Each device on the network must be individually configured with a specific IP address. This manual assignment provides administrators with precise control over each device’s network settings but can be time-consuming and prone to human error, especially in larger networks with numerous devices.

Network Management

DHCP centralizes network management, placing control in the hands of the DHCP server. This centralized approach streamlines network administration by allowing changes and updates to be implemented from a single point. It ensures consistency across the network, simplifying the overall management process and reducing the potential for errors.

Static IP addressing requires individual configuration for each device, leading to a decentralized network management approach. While this provides granular control over each device’s settings, it can be more complex and time-consuming, especially in larger networks. Changes must be made on a per-device basis, making it challenging to maintain uniformity across the entire network.

DHCP is easily scalable for large networks. As the network expands or contracts, DHCP can efficiently manage the allocation of IP addresses without manual adjustments on each device. The dynamic nature of DHCP makes it adaptable to changes in the network size, making it a scalable solution for diverse and evolving network environments.

Static IP addressing can become complex and challenging to manage in large networks. As the number of devices increases, the manual assignment of IP addresses becomes more time-consuming and error-prone. Network administrators may find it difficult to maintain an organized and efficient address scheme, leading to potential issues in network scalability.

Network Security

While DHCP itself doesn’t introduce significant security risks, improperly configured DHCP servers can be vulnerable to attacks such as IP address spoofing or unauthorized DHCP server deployment. An attacker may attempt to distribute false configuration information, potentially leading to network disruptions or unauthorized access.

Static IP addressing is generally less vulnerable to certain types of attacks compared to DHCP. Since the IP addresses are manually assigned and do not change dynamically, there is a reduced risk of unauthorized devices gaining access through deceptive DHCP configurations. However, the security of static IP addresses still depends on proper configuration practices and network security measures.

Reliability

The reliability of DHCP is closely tied to the availability and stability of the DHCP server. In DHCP-dependent networks, if the DHCP server experiences downtime or becomes unavailable, devices may struggle to obtain or renew their IP addresses, potentially leading to network connectivity issues. While DHCP servers are typically redundant in larger setups to mitigate this risk, the reliance on server availability remains a consideration for the overall reliability of DHCP-based networks.

Static IP addressing offers a more consistent and less reliant solution in terms of reliability. Once manually assigned, static IP addresses remain constant unless intentionally modified by the administrator. This stability ensures that devices with static IPs maintain their network presence even if DHCP servers encounter issues. In critical environments where uninterrupted connectivity is paramount, such as for servers and essential network infrastructure, the reliability of static IP addresses becomes a compelling factor.

Flexibility

DHCP provides a high degree of flexibility, especially in dynamic network environments. It easily adapts to changes in network configuration, such as the addition or removal of devices. When network changes occur, DHCP automatically adjusts the IP address assignments, simplifying the process of accommodating new devices or reconfiguring existing ones. This flexibility is particularly advantageous in environments where the network landscape frequently evolves.

While static IP addressing offers stability, it lacks the same level of flexibility as DHCP. Manual updates are required whenever changes in network configuration, such as IP address modifications or device relocations, are necessary. This manual intervention can be time-consuming, especially in large networks where numerous devices may need adjustments. Despite the control it provides, the static approach might pose challenges in environments that demand rapid adaptability to changing network conditions.

DHCP vs Static IP Addressing Use Cases

Home networks.

DHCP is particularly well-suited for home networks where simplicity and ease of setup are essential. In a typical home network environment, users connect various devices such as smartphones, laptops, and smart appliances. DHCP eliminates the need for users to manually configure IP addresses on each device, providing seamless connectivity. It ensures that devices can easily join and leave the network without requiring intervention, making it an ideal choice for non-technical users in a residential setting.

Small to Medium-sized Businesses

DHCP is widely adopted in small to medium-sized business networks. These environments often have a moderate number of devices that require connectivity, including computers, printers, and networked peripherals. DHCP’s automated IP address assignment and centralized management simplify network administration, allowing IT personnel to focus on other critical tasks. It also facilitates flexibility in scaling the network as the business grows or changes in device configurations occur.

Guest Networks

DHCP is commonly employed in guest networks, where a dynamic and temporary allocation of IP addresses is preferred. Guest networks are designed to accommodate visitors and guests who may bring their own devices. DHCP streamlines the onboarding process, as guests can connect to the network without manual configuration. The temporary nature of DHCP leases ensures that addresses are efficiently utilized and released when guests disconnect, enhancing overall network efficiency.

Static IP addressing is extensively used for servers in both small and large-scale networks. Servers require a consistent and unchanging network identity for seamless accessibility. Static IPs provide this stability, ensuring that servers are reliably accessible through a fixed address. This is crucial for services such as web hosting, email servers, and database servers, where a predictable and constant connection is vital for efficient operation.

Network Devices with Specific Configurations

Certain network devices, such as routers, switches, and network-attached storage (NAS) devices, often benefit from static IP addressing. These devices play central roles in network infrastructure and configuration, requiring a reliable and fixed network presence. Static IPs allow administrators to precisely control the network settings of these devices, ensuring consistent communication and facilitating proper network functionality.

Critical Infrastructure

Static IP addresses are commonly utilized for critical infrastructure components within a network, including firewalls, security appliances, and monitoring systems. These components demand a high level of reliability and predictability in network communication. Static IPs provide a stable and unchanging identity, reducing the risk of disruptions and ensuring continuous operation of essential network services. In critical infrastructure scenarios, the manual configuration process associated with static IP addresses is justified by the heightened need for control and security.

Which to Choose: DHCP vs Static IP Addressing?

When deciding between DHCP and Static IP addressing, it is essential to consider the specific needs and characteristics of the network. In dynamic environments where adaptability to changes is paramount, DHCP proves to be a valuable choice. Networks that frequently experience additions or removals of devices, such as in small to medium-sized businesses or guest networks, benefit from the automated and scalable nature of DHCP.

Conversely, for scenarios demanding precise control, stability, and predictability, such as in critical infrastructure or server environments, Static IP addressing is the preferable choice. Considerations should include the size of the network, the nature of devices connected, security requirements, and the level of control desired by the administrators. Striking a balance between flexibility and reliability ensures that the chosen IP addressing approach aligns seamlessly with the network’s specific demands, ultimately optimizing its performance and functionality.

The key differences between DHCP and Static IP addressing lie in their configuration processes, network management approaches, scalability, and security considerations. DHCP automates the assignment of IP addresses dynamically, providing efficient scalability and centralized management. It is well-suited for home networks, small to medium-sized businesses, and guest networks due to its simplicity and adaptability.

On the other hand, Static IP addresses involve manual and fixed configuration, offering control, stability, and predictability. Static IPs are often preferred for servers, network devices with specific configurations, and critical infrastructure where a consistent and unchanging network presence is crucial. The choice between DHCP and Static IP depends on the specific requirements and characteristics of the network.

1. What is the primary difference between DHCP and Static IP addressing?

Answer: The main difference lies in the method of assigning IP addresses. DHCP (Dynamic Host Configuration Protocol) automatically assigns IP addresses to devices on the network, while Static IP addressing requires manual configuration, with each device having a fixed and unchanging IP address.

2. Which is more suitable for a home network, DHCP, or Static IP addressing?

Answer: DHCP is generally more suitable for home networks due to its ease of setup and management. It eliminates the need for manual configuration, making it user-friendly, especially for non-technical users. Static IP addressing may be overkill for the typical home network unless specific devices, like gaming consoles or network printers, require a consistent IP.

3. Are there security considerations when choosing between DHCP and Static IP?

Answer: Yes, security considerations vary. DHCP, if not properly configured, may pose security risks, such as IP address spoofing. Static IP addressing is generally less vulnerable to certain types of attacks since the IP addresses are manually assigned. However, both methods require proper security practices, such as securing DHCP servers and implementing firewalls.

4. In which scenarios is Static IP addressing preferred over DHCP?

Answer: Static IP addressing is preferred in scenarios where devices require a consistent and unchanging network presence. This is crucial for servers, network devices with specific configurations, and critical infrastructure. Static IPs offer stability and predictability, making them ideal for environments where control over IP address assignment is paramount.

5. Can DHCP be used in large networks?

Answer: DHCP is suitable for both small and large networks. Its automated and scalable nature makes it adaptable to changes in network size, making it efficient for large environments. In contrast, Static IP addressing can become complex and challenging to manage in large networks due to the manual assignment of addresses, making DHCP a more practical choice for scalability in extensive network setups.

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Dynamic Host Configuration Protocol (DHCP) vs Static IP Assignment

The two different approaches of network configuration to manage IP addresses for devices are DHCP (Dynamic Host Configuration Protocol) and Static IP Assignment which you can use to configure computer networks and to assign IP addresses to devices on a network are the focus. A distinctive feature of DHCP is the automated assignment of IP addresses dynamically, while Static IPs do it the other way around, which means they do not assign fixed IP addresses manually. Being knowledgeable about the dissimilarities in methodologies is just like proficiency in network administration as meeting the unique needs of networking infrastructure.

Primary Terminologies

• Dynamic Host Configuration Protocol (DHCP): A network protocol that automates the allocation of IP address(es) to devices in a network and improves the IP address management processes.
• Static IP Assignment: Static IP addressing for gadgets and deployment of such addresses all over the network to avoid dynamic addressing sometimes.
• IP Address: It is a unique numeric code assigned to any device that is connected to a network which is used to communicate between the devices and to identify themselves.
• Network Management: The activity of controlling and maintaining IP address allocation and configuration.
• Configuration Complexity: The complexity and amount of labor that are involved in the task of IP address assignment within a network.
• Resource Usage: It is used to implement better IP address utilization, and IPv4 wasting is a possibility if not handled appropriately.
• Device Identification: To specifically characterize the devices according to their IP addresses allows effective network administration and resolving problems.
• IP Address Ownership: The system of IP addresses being either assigned temporarily by a DHCP (Dynamic Host Configuration Protocol) server or permanently assigned on the basis of the ownership of the separate devices.

Dynamic Host Configuration Protocol (DHCP)

Dynamic Host Configuration Protocol (DHCP) is a network protocol that enables automatic assignment of IP addresses (and other network configuring information) to devices being accessed on the network. The function of DHCP is to simplify IP address management processes as it allows the automatic allocation of addresses to devices when they connect to the network. In this merging of the IP address allocation makes the process more efficient and relieves you from the pain of assigning addresses manually to all devices.

Example: An office network provided with a DHCP server allot an IP address automatically to the new laptop joining the network. This intelligent allocation mechanism, the last device recognizes new onboarding process is easier.

Step-by-Step Process: DHCP

• The device communicated through the network.
• DHCP client transmits a data packet that is broadcast to receive an IP address.
• The DHCP server is subsequently given the address request and it gives an available IP address.
• The client signs off on the terms and inputs the IP address.
• DHCP server assigns IP to the client in addition to other config network information (subnet mask, default gateway, DNS servers, etc.)
• The client will be provided with the network prefix so that he can use it for network communication until the lease expires or the device disconnects from the network.

Static IP Assignment

DHCP is used to temporarily assign IP addresses while the static IP assignment is about the manual configuration of a dedicated IP for each device on the network. In contrast to the DHCP in which IP addresses change over time or sometimes differently, the static IP assignments make it possible to always use the same IP address for one device. Such a technique is employed in instances of network elements such as servers, printers, and other network infrastructure devices that require wire addresses.

Example: A network printer is assigned a static IP address just to ensure that its address does not change which it happens to be a very critical component because that is what enables other devices to communicate and collaborate with ease.

Step-by-Step Process: Static IP Assignment

• In network administration, a particular IP address is assigned by hand to a device.
• The device can now use this single fixed IP address to communicate with the network every time, providing reliability and predictability.

Dynamic Host Configuration Protocol (DHCP) vs Static IP Assignment – FAQs

What is the main difference between dhcp and static ip assignment.

DHCP provides dynamic IP address assignment, although Static IP Assignment requires implementing hard-coded static IP addresses for devices.

Which method offers more flexibility in IP address management?

DHCP provides simplicity and reliability in IP management while in case with the static IP address each machine gets the fixed and predictive IP address.

Is DHCP or Static IP Assignment better for large networks?

DHCP is common among larger networks since it can easily scale and has less complicated configuration.

Can DHCP and Static IP Assignment coexist in the same network?

Definitely, a network is always a collection of DHCP-assigned addresses and statically assigned addresses which are needed for particular devices on the network.

Do Static IP Assignments pose security risks?

Static IP Assignments is capable of affording more access to IP addresses usage and control, however, if not handled cautiously, it can expose machines to foreign IP addresses and other vulnerabilities.

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• trend-vision-one-deploy-pac-vmware-esxi

Deploying the Private Access Connector on VMware ESXi

Connect your VMware ESXi applications with Zero Trust Secure Access Private Access and prevent unauthorized intrusions.

• In the Trend Vision One console, go to Zero Trust Secure Access → Secure Access Configuration → Private Access Configuration .
• Provide a unique name and description for the group.
• Click Save .

• Select VMware ESXi from the Platform list.
• Click Download Disk Image to download the OVA file. Verify that the file name and extension are: TrendMicroVisionOne-PrivateAccessConnector.ova

• Sign in to the web vSphere Client, click ACTIONS , and then click Deploy OVF Template... . The Deploy OVF Template screen appears.
• Under Select an OVF template , click Local file , select the OVA file downloaded from the Trend Vision One console, and then click NEXT .
• Under Select a name and folder , specify a unique name and target location for the Private Access Connector virtual appliance, and then click NEXT .
• Under Select a computer resource , select a destination computer resource and click NEXT .
• Under Review details , verify the template details and click NEXT .
• Under Select storage , select the disk location and click NEXT .
• Under Select networks , select a destination network and click NEXT .
• Click the green Power On button on the top to power on the virtual machine, and then click the console button to open the virtual machine console.
• Sign in to the Private Access Connector virtual appliance with the default credentials. User name: admin Password: saseztna
• Enter the Command Line Interface (CLI), run the following command, and then press the Enter key to change your password: passwd The default password is saseztna . Your new password cannot be the same as the default password. The admin user and privileged mode share the same password.
• Type enable and then press the Enter key to enter privileged mode. Provide the updated password when asked. The command prompt changes from > to # .
• Use the CLI to configure the required network settings. After the Private Access Connector is installed, the default IP assignment method for your Ethernet interface is DHCP. To view the interface information, run the following command: ifconfig If your organization does not use a DHCP server, manually configure the static IP address, static route, and DNS server for your interface. For more information on available commands, see Private Access Connector CLI commands .
• (Optional) Run the following command to change the time zone of the Private Access Connector: configure timezone <timezone> The default time zone is America/Los_Angeles .

• Use the CLI to configure other settings, if required. For more information on available commands, see Private Access Connector CLI commands . After successful deployment, the Private Access Connector virtual appliance appears under the corresponding connector group on the Private Access Connectors tab.

• Services & Software

How to Change Your IP Address With and Without a VPN

You can refresh your IP address using several methods. Here's how to do it with a VPN, a proxy server, restarting your router, and manually or automatically updating it on your device.

Every internet-connected device has an IP address containing information about your general geographic location and internet service provider. Often, you don't have to think about an IP address — they're automatically assigned to internet-connected devices. But sometimes you’ll have to get a new IP address.

There are several ways to get a fresh IP address, including a virtual private network, a proxy server, rebooting your router or manually obtaining a new IP. Here are all the ways you can change your IP address.

How to change your IP address using a VPN

A VPN doesn't change your device's IP address but instead reroutes your traffic through an encrypted server so that apps and websites don't view your IP, but that of the server you're connected to. Essentially, it makes apps or websites think you have a different IP address. Your ISP can't see your online activity, like the apps you're using or websites you're visiting, and sites or apps view your traffic as originating from your VPN company's server. VPNs are great for situations where you want extra privacy, need to access geo-blocked content or have to bypass throttling restrictions and censorship.

Here's how to hide your IP address with a VPN:

• Sign up for a plan with a VPN provider .
• Download and install a VPN app on your device.
• Open the newly installed VPN app and sign in.
• Enable your VPN and select your preferred server.

The exact process for using a VPN varies slightly by device. You can quickly test whether your VPN is working correctly by looking up your IP address with your VPN toggled off and then on — the IP addresses shouldn't match.

How to change your IP address using a proxy server

A proxy server and VPN are similar because they're both middlemen between your device and the internet. Like VPNs, proxies hide your IP address from apps and websites. However, a proxy server doesn't encrypt your connection, so the connection isn't as secure or private as a VPN. A proxy may work for basic pseudo-anonymity for web browsing or streaming videos, but for an encrypted connection, you'll need a virtual private network. Before I switched to a VPN, I used a proxy service — GetFlix — to unblock geo-restricted content, like streaming TV shows from the Canadian Broadcasting Corporation while in the US.

Setting up a proxy server differs depending on the platform you're using. Generally, you'll configure your proxy server address in your device's settings, enable your proxy and choose an IP address. Some proxy services include user-friendly apps, so you can just download an app, sign in, start your proxy and pick a server.

How to change your IP address by resetting your router

Rebooting your router is a simple method for obtaining a new IP address:

• Check your IP address and make a note of it.
• Unplug your router for a minimum of five minutes.
• Plug your router back in — it may take a few minutes for your internet connection to return.
• Reconnect your device to your network if it doesn’t automatically do so.
• Recheck your IP address — this time, it should be different than it was when you first looked.

Your router assigns IP addresses to each connected device, so resetting it is supposed to make it forget your gadget and dole out a fresh IP address. Usually, it works, but sometimes it doesn't. If you still see the same IP address from before after a router reboot, try resetting your router again or for a longer period of time. Folks with a separate router and modem may need to reset both networking devices to obtain a new IP address.

How to change your IP address automatically or manually

Most devices let you easily update your IP address automatically, meaning you won't need to know a free IP address to use, unlike manually configuring an IP. Updating your IP address automatically is more user-friendly — you won't need to know a free IP address on your network to use. But sometimes you'll want to manually add an IP, like if you're running a home server and wish to assign a static IP address — for example, I host a Plex server and have a static IP address set up. Here's how to update your IP address manually and automatically on different platforms.

How to change your IP address on Windows

To automatically refresh your IP address:

• Open the Run dialog box by simultaneously pressing the Windows key and R button ( Win + R ). Alternatively, you can head to the Start Menu and search for Run.
• Type CMD and tap Enter to open a command prompt.
• Type ipconfig /release and hit Enter to give up the current IP address of your Windows machine.
• Type ipconfig /renew and tap Enter to get a new IP address automatically.

To manually update your IP address:

• Head to Start .
• Go to Settings .
• Select the Network & internet tab.
• Click Wi-Fi if you're using a wireless network or Ethernet for a wired connection.
• For Wi-Fi, select [network name] properties (for instance, my W-Fi name is WuTangSecret, so I clicked WuTangSecret properties ). With Ethernet, you don't need to select anything else to get to the IP assignment screen.
• Next to IP assignment , click Edit .
• Click Manual .
• Toggle on IPv4 or IPv6 , whichever you'd like to use or your router and modem support.
• Punch in the IP address you want to use.  

Alternatively, you can switch your IP address from the Control Panel:

• Open the Control Panel .
• Click Network and Internet .
• Visit the Network and Sharing Center .
• Select your network.
• Choose Properties .
• Click TCP/IP .
• Punch in the IP address you want to use. 

How to change your IP address on Mac

To automatically get a new IP address:

• Visit System Settings .
• Click Network .
• Select Wi-Fi , then the Details button next to your network.
• Select TCP/IP .
• Pick Renew DHCP Lease .

To manually obtain a fresh IP address:

• Go to System Settings .
• Choose Configure IPv4 > Manually or Configure IPv6 > Manually .
• Type in your desired IP address.

How to change your IP address on Linux

• Open the Application (you can do this by pressing the super key, which is the Windows button or Command key on an Apple keyboard).
• Launch the Connections application.
• Select your network, then click the IPv4 or IPv6 tab.
• Switch Method to Manual .
• Enter the IP address of your desired DNS server in the DNS Servers section.

Note that these instructions might vary slightly depending on the specific Linux operating system you're using, but should generally be the same for most Debian-based OSes, like Ubuntu, Kubuntu or Linux Mint.

How to change your IP address on Android

• Head to Settings .
• Tap Wi-Fi .
• Press the i button beside the Wi-Fi network you're connected to.
• To automatically get a new IP address: Tap Forget to disconnect from your wireless network — it's a trashcan icon. Then reconnect to your Wi-Fi network and you should get a new IP address.
• To manually refresh your IP address: Tap IP settings . Select Static . Enter the IP address you'd like to use.

How to change your IP address on iOS and iPadOS

• Select your wireless network.
• Press Configure IP .
• Pick Automatic to automatically refresh your IP address, or tap Manual , then punch in an IP address of your choice.

What is an IP address?

An Internet Protocol — or IP — address is a unique string of four numbers used to identify an internet-connected device. For instance, your IP address might look like 192.168.1.96. An IP address is like a phone number. Similar to your cell phone number, your IP address contains information about your geographical location. You can look up your own IP address using a website like the aptly-named WhatIsMyIPAddress , where you’ll find information such as your internet service provider and your approximate region.

Why would you want to change your IP address?

If you can view info like your ISP and general physical location by looking up your IP address, other entities — your ISP, websites you visit or apps you use — can glean this sort of data as well. You might want to change your IP address for privacy reasons. 

Some apps and websites, like streaming services, are region-restricted, so you can't access them outside of certain countries. A new IP address from a specific country can help unblock geo-protected content, like foreign Netflix libraries.

You can change your IP address to circumvent censorship, like viewing websites blocked by your government or school administration. Likewise, a fresh IP address could allow you to bypass throttling restrictions from your ISP or mobile carrier.

Changing IP addresses may help you get your device working again if there's an issue with its connectivity to your router or modem, which is helpful for IT troubleshooting.

How to change your IP address FAQs

Is it possible to change your ip address.

It is possible to change your IP address. You can refresh your IP address using a VPN, with a proxy server, by restarting your router or manually and automatically refreshing your IP address on your device.

Is it legal to change your IP address?

In the US, it is legal to change your IP address. Often, your IP address may even update automatically when reconnecting to your Wi-Fi network. But altering your device’s IP address to impersonate a person or business, which is called IP spoofing, could violate the US Computer Fraud and Abuse Act. So long as you’re abiding by local laws, simply changing your IP address should be completely legal.

Can you change your IP address for free?

You can change your IP address for free. In fact, most methods for getting a new IP address -- manually or automatically updating your IP address and restarting your router -- don’t cost any money. Using a proxy server or VPN service might, although you can use a free VPN like Proton VPN’s no-cost tier to change your IP address without spending a dime.

Does resetting a router change your IP address?

Yes, restarting your router normally changes your IP address if you’re using a dynamic IP address. But if you’re using a static IP, it won’t automatically update with a router reset -- instead, you’ll need to manually update it.

Does your IP address change when you use different Wi-Fi?

Yes, your IP address changes when you use a different Wi-Fi network. However, you can establish a static IP address so you’ll always use the same IP address on a particular wireless network, but you can’t configure the same IP address to use across all Wi-Fi networks.

How can you look up your current IP address?

You can quickly find out your current IP address by using a website like WhatIsMyIPAddress .

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