All of you know that we didn't have any Faileover option for DHCP in the past. So must of us created different DHCP scopes for one IP range on diffenrent servers. This was needed to get a partly redundant DHCP option. This was working but any changes for reservations, scope changes or configuration changes must be done manualy or with scripts. This took time or wasn't realy successfull. Now with Windows Server 2012, we get a real Failovercluster including configuration replication. Please notice, the only available options are load balanced and hot standby. I will explain you later when you should use which option. So let us start to configure our cluster.  

1. You need to install the first DHCP Server and configure the DHCP Scope. This DHCP Server has to be Windows Server 2012 Standard or Datacenter.

http://de.community.dell.com/techcenter/os-applications/w/wiki/689.how-to-configure-dhcp-on-windows-server-2012.aspx

In this scenario I configured the first DHCP Server on Flo-SVR-DC01.  

2. Next install a new server with Windows Server 2012 or take one other free server from your existing Windows Server 2012 Systems as Windows Server 2012 DHCP Failover Clusterpartner.

How to install a Windows Server 2012 

http://de.community.dell.com/techcenter/os-applications/w/wiki/666.how-to-install-windows-server-2012-in-a-hyper-v-vm.aspx

First Configuration of a Windows Server 2012 

http://de.community.dell.com/techcenter/os-applications/w/wiki/670.first-configuration-of-a-fresh-installed-windows-server-2012.aspx

In my case I installed a fresh Windows Server 2012 VM as Failover Partner.  

3.  Now your could add the new node to your Server Manager, if you want to manage the Server remote. You can also configure the Failover Setup without this, but it helps to manage both Servers later.

http://de.community.dell.com/techcenter/os-applications/w/wiki/739.add-other-windows-server-2012-system-to-server-manager-for-remote-management.aspx

4. When the DHCP role was installed correct on the second host and you added the server for management to your management host, than you should see both systems under DHCP.

5. In the next step open the DHCP MMC.

6. In the DHCP MMC please add the second DHCP Server first. You can do this via right click on "DHCP" and than "Add Server".

http://de.community.dell.com/techcenter/os-applications/w/wiki/796.how-to-add-second-server-to-mmc-example-dhcp-server.aspx

7. Now you should see both DHCP Servers in the list.

12. In the next step we authorize the DHCP server to our Domain.

http://de.community.dell.com/techcenter/os-applications/w/wiki/795.how-to-authorize-a-windows-dhcp-server-to-active-directory-ad-adds.aspx

13.  Now click right on the scope that you want to cluster and select "Configure Failover".

14. When the Wizzard starts, you see the Scope that can be clustered.

If you see no available Scope, you have to check if DHCP Service is up, DHCP Server is complet configured and there are no issues with DNS and ADDS.  

15. Next step is to selecte the failover partner.

16. When you authorized the second DHCP server before, you see it in the second list. Otherwise you have to select "This Server:" and "Browse".

17.  Now you type in the name of the server.

18. When you entered the name click “Check Names”. When the wizzard found the server, click “ok”.

19. Click “ok” and the server will attached to DHCP MMC.

20. Now you see the selected Server with complet FQDN in the Patern Server field.

Click "Next" to go on.  

21. Now you have to set the clusterconfiguration.

Load Blanced:

Relationship Name: Name of your Failover Cluster

Maximum Client Lead Time: Defines the amount of time the surviving server will wait before assuming control of the entire scope.

Mode: Load Balanced - When the cluster is configured in Load Balance mode, this results in an active-active setup of the two DHCP Servers. You should use when you have big networks with many clients or you want to deploy the cluster in different branch offices.

Load Balance Percentage: Means how the work is splitted up between both hosts. The percentages together can only be 100%. The node with the highest percentage gets the highest workload.

State Switchover Interval: automatically change state to partner down after <time>.

Enable Message Authentification: enables authentification from clusternodes.

Shared Secret:Validation Passwort that identifies the node as partners against each other.  

Standby:

Relationship Name: Name of your Failover Cluster

Maximum Client Lead Time: Defines the amount of time the surviving server will wait before assuming control of the entire scope.

Mode: Hot Standvy - When the cluster is configured in Hot Standby mode, one node is active and the second is standby and will only take over when the primary DHCP Server failes. You should use when you need the partner as fault tolerance.

Adresses reserved for standby server: Means how many adresse the standby can lease before he takes over the entire scope and becomes active.

State Switchover Interval: automatically change state to partner down after <time>.

Enable Message Authentification: enables authentification from clusternodes.

Shared Secret: Validation Passwort that identifies the node as partners against each other.  

22. After klicking "Next" you see a short summary of your configuration.

23.  Klick "Finish" and the cluster configuration starts.

24. In the DHCP MMC click right on the Scope and force a replication by clicking on "Replicate Failover Scope" and than on the refresh  button or press F5.

25. On the failover node check the config. If the config is right your finished.