ARP (Address Resolution Protocol) performs mapping of an IP addresses to Ethernet/ Physical Address. The protocol operates below the Network Layer as a part of the OSI Link Layer, and is used when IP is used over Ethernet.
A machine who wants to get a MAC Address sends an ARP request in the form of packets “Is your IP address X.X.X.X? If so, send your MAC back to me (Y.Y.Y.Y).” These packets are broadcast to all computers on the LAN, even on a switched network. Each computer examines the ARP request, checks if it is currently assigned the specified IP. Then the target system forms an ARP Response “Yes. I’m X.X.X.X, here is my MAC Address hh:hh:hh:hh:hh:hh”, and sends an ARP reply containing its MAC address or Physical Hardware Address.
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