ARP (Address Resolution Protocol) is

Address Resolution Protocol (ARP) is a network protocol used to find the MAC (Media Access Control) address of a recipient within the local network segment. When a device wants to communicate with another device on a local area network (LAN), it needs to have the target device’s MAC address to send frames across the network. If the sender only knows the IP address of the target device, it uses ARP to map that IP address to its corresponding MAC address. Here’s how ARP works:

1. The sending device broadcasts an ARP request packet to all devices on the local network, asking for the MAC address associated with a specific IP address.
2. All devices on the local network receive the ARP request, but only the device with the matching IP address responds.
3. The device with the matching IP address sends an ARP reply packet back to the requester, providing its MAC address.
4. The sender, now knowing the MAC address of the target device, can send the packet directly to that device.

ARP operates mainly on IPv4 networks, and its functionality is crucial for the normal operation of local area networks. For IPv6 networks, a similar function is performed by the Neighbor Discovery Protocol (NDP).