DHCP Failover is a new feature in Windows Server 2012 which provides for high availability of DHCP service.  Two DHCP servers in a failover relationship synchronize the IP address lease information on a continual basis, there by keeping their respective databases up-to-date with client information and in sync with each other. In Windows Server 2012, DHCP Failover did not support BOOTP clients. So, if you had a DHCP scope which was of type BOOTP or BOTH (DHCP and BOOTP), you will not be able to configure DHCP Failover for these scopes. Based on feedback from customers who were using scopes of type BOOTP or BOTH for supporting PIXIE environment, DHCP Failover in Windows Server 2012 R2 has been enhanced to support scopes of type BOOTP and BOTH! As per BOOTP protocol, the IP address given to a BOOTP client is given forever without any lease expiration. This runs counter to the use of MCLT (a short lease duration) in DHCP failover for any new lease or while operating in COMMUNICATION INTERRUPTED or PARTNER DOWN state. An expired lease can be reclaimed by the DHCP server and offered to a different client. To avoid the issue of a BOOTP client's IP address being given to a different client by a DHCP failover server operating in COMMUNICATION INTERRUPTED or PARTNER DOWN state, it is highly recommended that conflict detection check be enabled on the DHCP failover servers with scopes of type BOOTP or BOTH.