What is "address resolution protocol"

n. (context computing Internet English) The protocol used to translate IP number into MAC address to support communication on a LAN.

The Address Resolution Protocol (ARP) is a telecommunication protocol used for resolution of Internet layer addresses into link layer addresses, a critical function in multiple-access networks. ARP was defined by RFC 826 in 1982, is Internet Standard STD 37, and is also the name of the program for manipulating these addresses in most operating systems.

ARP is used for mapping a network address (e.g. an IPv4 address) to a physical address like an Ethernet address (also named a MAC address). ARP has been implemented with many combinations of network and data link layer technologies, like IPv4, Chaosnet, DECnet and Xerox PARC Universal Packet (PUP) using IEEE 802 standards, FDDI, X.25, Frame Relay and Asynchronous Transfer Mode (ATM). IPv4 over IEEE 802.3 and IEEE 802.11 is the most common case.

In Internet Protocol Version 6 (IPv6) networks, the functionality of ARP is provided by the Neighbor Discovery Protocol (NDP).