Windows Server DHCP Server Failover Setup

In this article, we will discuss the previous article Windows Server What is DHCP Server, its installation and configuration then, now too DHCP Failover We will focus on its installation and configuration. DHCP Server Failover, introduced with Windows Server 2012 and continued in Windows Server 2019 feature in your network environment DHCP It performs a critical function by ensuring the uninterrupted operation of the service.

• Windows Server DHCP Server Installation – Cengiz YILMAZ

DHCP Server Failover Importance and Failover Working Methods

DHCP servers, devices on your network IP address Due to their vital role as a server, any downtime of any of these servers could negatively impact communication across all devices on the network. Windows Server 2012 and comes with Windows Server 2019also found in DHCP Server Failover feature is designed to prevent this type of interruption.

DHCP Server Failover can operate in two basic modes:

1. Load Balance Mode: In this mode, two DHCP The server also works actively and performs load balancing. In this way, any disruptions that may occur on one server are balanced by the other server and service continuity is ensured.
2. Hot Standby Mode: When a server is active in this structure (primary), the other is passive (standby) as expected. When the active server becomes unavailable for any reason, the passive server takes over and continues the service.

Windows DHCP Server Role Installation

• Server Manager from your dashboard “Add roles and featuresClick ”.

• "before you beginAfter the page ”NextPress the ” button.
• "Select installation type” on the page “Role-based or feature-based installation” option and select “Next" and proceed by saying.
• "Select destination server” screen, DHCP Server Select the server you will install and click "NextContinue with “.
• "Select server roles” screen, “DHCP Server” role. When you select this role, the associated features (Features) is also specified to be installed.
• "Add FeaturesBy clicking on the " button, you can select the required features (DHCP Server Tools and confirm the installation of “NextContinue by saying, "

• "Select featuresYou do not need to make an extra selection on the " screen, just select "Next" and proceed by saying.
• "ConfirmationThe installation summary is reviewed on the “ ” screen.Restart the destination server automatically if required” option to allow the server to automatically restart if necessary and “install" Start the installation by saying.

• After the installation is complete "Complete DHCP configurationWith the option " DHCP Post-Install Configuration WizardStart the .

• "Authorization” screen, DHCP Server Active Directory Domain to authorize with “Use the following user's credentialsSelect the ” option and Administrator Enter your account information. Alternatively, you can authorize with another AD user account or “Skip AD authorizationYou can skip AD authorization with ”.

• "Commit” and complete the configuration by saying “CloseClose the wizard with ”.

• Server ManagementFrom the “Tools” menu in r, select “DHCPBy selecting the option ” DHCP open the management console.

With these steps DHCP The installation and initial configuration of the server role is complete. Now, DHCP Failover You can proceed with the installation of the feature and make configurations that will ensure the uninterrupted operation of your network.

Windows DHCP Server Failover Configuration

Failover To start the configuration, first, the primary DHCP Open the server console. To start this process IPv4 Right click on the object and select "Configure FailoverClick ”.

• "Introduction to DHCP Failover” screen, fail over You will need to select the scopes to configure. If you have more than one scope if any and all fail over If you want to include it in the configuration, “Select all” option. If you only want to configure a specific scope, “Take your pickRemove the “l” sign and select the relevant scope. Then, select “NextContinue with “.

"Specify the partner server to use for failover" screen, you need to specify the partner server to be used for failover. "AddServerAdd your partner server using the " " button.

"Create a new failover relationship” on the screen fail over You will make the necessary settings for its configuration.

• Relationship Name: Enter a descriptive name for the failover cluster.
• Maximum Client Lead Time (MCLT): This is the time period defined in addition to the DHCP client's lease time. For example, if the DHCP lease time is set to 8 hours and the MCLT value is 1 hour, the total lease time is 9 hours. This time is sent to the second server, which is the failover partner, to be added to the end of the lease period.

DHCP Server Failover Mode and Features

Load Balance Mod:

• This mode has two DHCP Configures the server to load share. Both servers run in active-active mode and share the load equally. This mode is ideal for environments that require high availability and load balancing.

2. Hot Standby Mode:

• In this configuration, one server is actively serving while the other server is passively waiting. If the active server becomes unavailable for any reason, the passive server takes over and continues the service. This mode is critical DHCP ensures the continuous availability of its services.

3. State Switchover Interval:

• This setting is a DHCP determines how long it takes for a server to transmit its status to another server when the network connection is lost. If this setting is not checked, the status change is not made by the administrator. DHCP Server console or PowerShell must be done manually with .

4. Enable Message Authentication:

• This feature, DHCP inter-server fail over It is used to verify the replication. It is important to ensure a secure replication process.

5. Shared Secret:

• Inter-server DHCP Failover in the connection replication This password is used to ensure the security of the replication data.

6. Deployment Topology:

• DHCP Failover In the configuration, two servers are usually used and only IPv4 It is applied to domains. Servers can be on the same or different networks. Usually, a server is actively Production in the environment, the other is Disaster Recovery (DR) in position Hot Standby is configured in mode. Production In case of a network outage on the server, IP address distribution is automatic. DR is transferred to the server at location.

DHCP Failover Its configuration serves a critical function to ensure continuity of DHCP service on your network.

RFC 2131 according to the standards, DHCP Failover in the installation, the main DHCP the IP address that the server leases to a client DHCPACK Before you confirm with the message, you must check both rental records DHCP must also be saved on the server. 
However, this process DHCP because it can negatively affect the performance of the primary DHCP the server gives the client its IP address and DHCPACK After confirming with , a replication update package will be sent to the second replication partner. DHCP If communication between the primary server and the failover partner is interrupted, the specified Maximum Client Lead Time (MCLT) The term is added to the end of the lease term, which allows for a temporary extension of the lease term.

Summary you perform on the screen DHCP Review your failover configurations one last time. If everything is configured correctly, “FinishClick the " button to complete the process. This step saves your configuration and DHCP Failover will finalize your installation.

After installation, DHCP Server Going back to the management console, “Failover RelationshipYou can see your new configuration under the ” object. This view confirms that the failover relationship has been successfully established and is active.

DHCP Server Replication Operations

DHCP Open the management console. Right-click on the IPv4 object and select “Replicate Failover ScopesClick on ”. This process will change the connection between two servers. DHCP scopes and ensures that both servers are up to date and in sync. The replication process can also be triggered manually when any changes are made.

DHCP Server Failover installation and configuration is now complete. With this configuration, your network DHCP service has become more reliable and uninterrupted. This solution ensures that even in the event of potential server failures or network outages, DHCP ensures continuity of service.

Final Notes

DHCP Failover This feature provides a great layer of security for critical network infrastructures and ensures continuity of IP address management.

Thanks for reading. See you!