DHCP failover - BlueCat Integrity - 9.5.0

Address Manager Administration Guide

Product name
BlueCat Integrity

The DHCP failover protocol provides a method for two DHCP servers to communicate with each other.

Depending on the configuration, failover can provide both redundancy and load balancing. DHCP failover works by sharing one or more pools between two DHCP servers. The two servers are known as failover peers.

After placing two DHCP servers into a failover relationship, the addresses in each DHCP pool are divided between them. Half of the addresses are sent to the secondary server and half remain on the Primary server.

Failover peers don't need to be located in the same subnet, which provides you a great deal of flexibility when determining where to locate your DHCP servers.

  • DHCP failover is only supported on BlueCat DNS/DHCP Servers. DHCP failover isn't yet supported on other types of managed servers.
  • Enabling or disabling DHCP failover will restart the DHCP service, resulting in a service interruption.
Note: When designing your DHCP pools, we recommend that you size your pools so that a single server can handle the DHCP load should the failover peer go offline. We also recommend that you enable the BlueCat DNS/DHCP Server Monitoring Service and configure a Notification Group subscribing to the Monitoring Service so that you are notified when a failover peer goes offline. For information on monitoring, refer to Monitoring DNS/DHCP Servers.
You can view the DHCP failover state from the Administration console.
  1. From Main Session mode, type configure dhcp and press ENTER.
  2. Type failover-state and press ENTER.