In Part 1, we looked at how DHCP failover works and now should have a good understanding. In this article, we’ll take a look at how to configure DHCP failover between two DHCP servers. One has a scope which we want to configure failover for, using the other server for failover.
This test lab includes the below servers:
Here we’ll walk through how to configure DHCP failover. Our requirements are below:
- Scope 10.0.1.0/24
- Failover mode: Load balance mode (50:50)
- Automatic failover
PrerequisitesTo create a failover relationship for two standalone DHCP Servers, this requires:
- two DHCP servers
- a unique failover relationship name
- a DHCP scope on only one of the DHCP servers to configure failover for (this is because the scope will be created on the other DHCP server)
How to configure failover using the GUI
These instructions are for the DHCP MMC snap-in.
1) Open the DHCP MMC snap-in
2) Create a DHCP scope as normal on one of the two servers and set your scope options and DHCP reservations if not done already.
3) Right click the IPv4 node and click on Configure Failover:
4) Select the DHCP scopes you would like to configure for failover then click next
5) Add the partner DHCP server and click next
6) Here we’ll create a new failover relationship. We’ll configure:
- Relationship Name
- Maximum Client Lead Time: 1hr (default)
- Mode: Load balance (default)
- Load Balance Percentage: 50:50 (default)
- State Switchover Interval: 1hr (we set this so that the server progresses from COMMUNICATIONS INTERRUPTED to PARTNER DOWN state automatically so it doesn’t require administrator intervention before failing over)
- Shared Secret (this is used to authenticate messages between the servers)
7) Once done, confirm the stings and click Finish:
8) On the completion window, click Close:
We can then confirm that the scope exists on the partner server. All scope options, reservations and leases should be copied over. See below.
In this post, we looked at how to configure DHCP failover for a scope using the DHCP Management Tools. In Part 3, I'll run through how to configure DHCP failover with PowerShell.