Carrier Grade DHCP Server

DHCP severs can not achieve a high availability of 99.99 % without the use of stand-by server with automatic failover. For hot standby, there is a design or perhaps network architecture problem that only one single DHCP server can be placed in a network. What I know is that this problem has been tackled by IETF by developing the DHCP Failover Protocol. It works this way, a main server is keep communicating with the standby server about the IP adresses allocation and the standby server will not lease IP addresses to host. When there is a problem in the main server, the standby server will automatically take over and the previously addresses allocations by the main server before failure are known. This seamless takes over can ensure the provision of carrier-grade DHCP Server.