How To Configure DHCP Failover in Windows Server 2016

In the previous post, we have discussed how to configure DHCP server in Windows Server 2016. In this post, we will explain a step by step guide to configure DHCP Failover in Windows Server 2016. We assume that you have already read how to configure DHCP server post. If you missed it, please visit it, so you can get a clear idea what topology we are going to use for DHCP Failover configuration. The DHCP server configuration details are as follows:

  • Server Name: dc1.mcsalab.local
  • Server IP: 10.0.0.100/8
  • Scope Range: 10.0.0.220 – 10.0.0.235
  • Excluded Range: 10.0.0.220 – 10.0.0.225
  • Reserved IP: 10.0.0.230 for CL1

We are using Windows Server 2016 (TP 5), the same steps can be followed if you are using Windows Server 2012/R2.

Understand Lab Setup Topology

In order to demonstrate DHCP Failover configuration, we will add an additional DHCP server named server1.mcsalab.local (10.0.0.101/8) to provide high availability and redundancy. In the DHCP failover deployment, two DHCP servers work together in the Master (Primary) and Backup (Secondary) roles. Both the servers share the load of DHCP service and maintain the IP address allocation. One of the DHCP server from the DHCP Failover group takes the responsibility of the partner DHCP server when the partner server fails to allocate TCP/IP settings to the DHCP clients.

Since the dc1.mcsalab.local server is already configured as Primary DHCP server, we will start directly to configure DHCP failover. So, we will not cover how to configure DHCP server in this post. You have to visit the previous post for the step by step DCHP configuration.

Steps to Configure DHCP Failover

To configure DHCP Failover in Windows Server, you need to perform the following steps:

  1. On the partner DHCP server1 (Server1), open the Server Manager tool and launch the Add roles and features wizard. Select the DHCP server role and install it using the default selections.Installing DHCP Server Role
  2. Once the DHCP server role is installed, you need to authorize it. To do so, click the notification icon in the Server Manager tool and then click complete DHCP installation link.
  3. Navigate to the Authorization page, click Specify and specify your domain credentials (Domain\Username).
  4. Finally, commit the changes.Authorize DHCP Server in Active Directory
  5. Once the DHCP server role is installed and authorized on Server1, move on to Primary DHCP server (DC1) and open the DHCP Management console.
  6. Under the IPv4 node, select and right click your scope name and then select Configure Failover.Seleting scope to configure DHCP Failover
  7. On the next page, select the scope for which you want to configure failover and then click Next.
  8. On the next page, click Add Server. Type your partner server name (Server1) and then click OK to add the partner server. Click Next to continue.Add Secondary DHCP Server
  9. On the Create a new failover relationship page, specify a failover relationship name, MCLT value, role of the partner server (failover mode),  and the shared secret key. Refer the following figure and spend some time to understand the failover relationship options that we have selected.Selecting DHCP Failover Options
  10. Click Next and finish the wizard. Verify that you have successfully added the partner server.Completing Failover wizard
  11. Now, move on to Server1 and refresh the DHCP Management console. Expand the IPv4 node and verify that the DHCP scope of the Primary DHCP server (DC1) is reflected on Server1 and ready to allocate IP addresses.Verify DHCP Failover on Partner Server

In the preceding figure, notice the symbol of IP4 node.

Verifying DHCP Failover Configuration

  1. To test and verify your DHCP failover configuration, right-click dc1.mcsalab.local and stop the DHCP service.Stopping DHCP Service
  2. Move on to CL1, open the Command Prompt window, and execute the following commands to release and renew the TCP/IP settings.ipconfig /release 
    ipconfig /renew

     

  3. In the following figure, you can see that the same IP address is allocated by the partner server, even the primary DHCP server (dc1.mcsalab.local) is still out of service.ipconfig /release and renew

Recall: DHCP Failover is a service that allows one DHCP server to take the responsibility of other DHCP servers from the configured DHCP failover relationship group. Thus, this feature provides the load balancing, high availability, and redundancy for the DHCP service. That’s all you need to do to understand and configure DHCP failover in Windows Server 2016. Hope, you loved it.

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