What is an ARP, and how does it work?

In the OSI model, the Address Resolution Protocol is a network layer communication protocol. Its job is to find the MAC address for the system’s supplied IP address. It takes a 32-bit IPv4 address and transforms it to a 48-bit MAC address.

How ARP works is as follows:

  • It makes an ARP request to the whole network, which broadcasts frames.
  • The ARP request is received by all nodes on the network.
  • To determine the target’s MAC address, the nodes compare the request to the ARP table.
  • If it doesn’t match, the packet is discreetly discarded by the nodes.
  • If they match, the target will send a unicast ARP response to the original sender.