Configure DHCP Failover

So what is DHCP failover , well simply put its when two dhcp servers share a pool of addresses, they can be configured either for Load balancing or as a hot standby server relationship.

In Hot standby one server will take the active role in handing out addresses whilst the other server is in passive and will only come into play when the Active server cannot be contacted

In Load Balancing mode both servers will be active and provide addresses to clients.

Some advantages of using DHCP Failover:

  • High availability – Reduce the chances of the dhcp process failing and stopping a critical service.
  • If Load balancing is used then it can split the workload over the two Servers.

Step 1:

  • Configure a new server with the DHCP role installed. Remember to create a static IP Address on the Server and add it to the Domain (As in Previous how to guides)
  • Now open your first DHCP Server, Open Server Manager and Select Tools then DHCP.

Step 2:

  • Drop Down IPV4 and right Click on Scope and select Configure Failover

Step 3:

  • Read through the Description Select the scopes you need
  • Click Next

Step 4:

  • We now need to provide the Address path to the second server we created
  • Click Add Server

Step 5:

  • Select the second dhcp if its not listed browse for it
  • Click Ok

Step 6:

  • You will note the different Boxes. Just to run through quickly
    Relationship Name = What ever you would like to call it E.g DHCP Failover
    Maximum Client Lead Time = maximum amount of time that one server can extend a lease for a client's binding beyond the time known by the partner server.
    Mode = Load Balance/Hot Standby (Pretty Self Ex planetary)
    Load Balance Percentage = Self Ex Planetary
    State Switchover Interval = DHCP server will automatically place its partner into down state when it can’t communicate with other server
    Enable Message Authentication = Shared Password between servers if you wish to set this up
  • Click Next

Step 7:

  • Click Finish

Step 8:

  • Click Close

    Congratulations you have now configured DHCP, you can test (I like to test by stopping the dhcp service running on the one machine then running the cmd ipconfig /release then renew to see if it moves over to the secondary server)