WindowsServer

Server 2012 – Enable DHCP Failover Cluster

Windows Server 2012 introduced a new feature with the DHCP Service: the built-in DHCP Failover Cluster. This function was requested for a long time.

Before Server 2012, if you want to failover your DHCP, two possibilities:

  • Create a real cluster, and add the DHCP role.
  • Split the scope between two servers. With Server 2008, a Wizard simplifies this task.

In Windows Server 2012, it is really simple to add High Availability for DHCP Service. Each server can release lease to client and the information is synchronised between all failover members.

Let’s see how to implement the Failover Configuration:

DHCP Servers

  • On the first DHCP Server, check that the targeted scope is defined:
DHCP Targeted Scope

DHCP Targeted Scope

  • Once the DHCP Service is installed on the second server, don’t forget to authorize it in Active Directory:
DHCP Server Authorize

DHCP Server Authorize

DHCP Failover configuration

  • On the scope that you want to HA, right click on it, and select Configure Failover:
DHCP Failover Configuration

DHCP Failover Configuration

  • If you want to Failover several scopes, select them and click on Next.
DHCP Failover Wizard

DHCP Failover Wizard

  • Specify the second server in the configuration:
DHCP Partner

DHCP Partner

DHCP Partner

DHCP Partner

DHCP Partner

DHCP Partner

  • Select options for the relationship:
    • Mode: Load balance or Host Standby
    • Shared Secret.
DHCP Failover Options

DHCP Failover Options

  • Validate and check the creation of the Failover link:
DHCP validation

DHCP validation

DHCP Failover Creation

DHCP Failover Creation

Shared information

When the Failover is configured for a scope, information are replicated between partners. This means that lease delivred by one server is registered for the other member. This prevents the second to give the same IP address to another client.

DHCP Failover Partner Relationship

DHCP Failover Partner Relationship

First Server lease

First Server lease

Second Server lease

Second Server lease

More

You can get more information about DHCP Service here.

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