Address Resolution Protocol

The Address Resolution Protocol (ARP) is a communication protocol for discovering the link layer address, such as a MAC address, associated with an internet layer address, typically an IPv4 address. The protocol, part of the Internet protocol suite, was defined in 1982 by RFC 826, which is Internet Standard STD 37. ARP enables a host to send, for example, an IPv4 packet to another node in the local network by providing a protocol to get the MAC address associated with an IP address. The host broadcasts a request containing the target node's IP address, and the node with that IP address replies with its MAC address. ARP has been implemented with many combinations of network and data link layer technologies, such as IPv4, Chaosnet, DECnet and Xerox PARC Universal Packet (PUP) using IEEE 802 standards, FDDI, X.25, Frame Relay and Asynchronous Transfer Mode (ATM). In Internet Protocol Version 6 (IPv6) networks, the functionality of ARP is provided by the Neighbor Discovery Protocol (NDP).