The Reverse Address Resolution Protocol (RARP) is an obsolete computer communication protocol used by a client computer to request its Internet Protocol (IPv4) address from a computer network, when all it has available is its link layer or hardware address, such as a MAC address.

What is the use of ARP and RARP?

ARP stands for Address resolution protocol and RARP is an abbreviation for Reverse Address Resolution Protocol. Both are LAN protocols and are quite similar in some ways. Both use Broadcast in Request and unicast in response. Both ARP and RARP have the objective to complete the IP address to MAC address mapping.

What is RARP and why is it needed?

Reverse Address Resolution Protocol (RARP) is a network protocol used to resolve a data link layer address to the corresponding network layer address. For example, RARP is used to resolve a Ethernet MAC address to an IP address.