Reverse Address Resolution Protocol. Maps an IP address to a known hardware address. It can be used at startup by being programmed into the firmware, which allows devices that do not know their IP address on startup to issue an ARP request that has their BIA. The reply from the RARP server will supply the right layer 3 address. Most computers use DHCP instead of RARP. They can provide more information and can be routed off the local data link.