Back Address Resolution Protocol AN بروتوكول اقتران العناوين Arabic Address Resolution Protocol Bulgarian Address Resolution Protocol BS Address Resolution Protocol Catalan Address Resolution Protocol Czech Address resolution protocol Danish Address Resolution Protocol German Address Resolution Protocol Greek Protocolo de resolución de direcciones Spanish
| Internet protocol suite |
|---|
| Application layer |
| Transport layer |
| Internet layer |
| Link layer |
The Address Resolution Protocol (ARP) is a communication protocol used for discovering the link layer address, such as a MAC address, associated with a given internet layer address, typically an IPv4 address. This mapping is a critical function in the Internet protocol suite. ARP was defined in 1982 by RFC 826, which is Internet Standard STD 37.
ARP is required when a host wants to send an IPv4 packet to another node within the same network but doesn't know that node's MAC address yet. The host broadcasts an ARP request containing the node's IP address, and the node with the corresponding IP address returns an ARP reply that contains 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).