An Ethernet Address Resolution Protocol
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D. Plummer · 1982-11
Abstract
The Address Resolution Protocol (ARP) describes a method for mapping network layer addresses (such as IPv4 addresses) to link layer addresses (such as MAC addresses) on broadcast networks like Ethernet. ARP operates by broadcasting a request containing a target IP address and receiving a unicast reply containing the corresponding hardware address.
Why This RFC Matters
ARP is one of the fundamental glue protocols of TCP/IP networking. Every IPv4 packet sent on a local network segment depends on ARP to resolve the destination's hardware address before transmission. Despite its age and well-known vulnerabilities to ARP spoofing attacks, ARP remains ubiquitous in Ethernet and Wi-Fi networks worldwide. Its simplicity — a two-message request/reply exchange — has made it a durable solution for local address resolution for over four decades.