Address Resolution Protocol (ARP)
Network Fundamentals
Overview
ARP maps an IPv4 next-hop address to a link-layer address on the local segment. For a remote destination, a host resolves the default gateway MAC, not the remote host MAC. Requests are normally broadcast; responses update local neighbor state. ARP does not authenticate the sender.
Protocol stages
- 1Destination subnet decision
- 2Broadcast ARP request
- 3Unicast ARP reply
- 4Cache mapping
- 5Ethernet delivery
Interactive exercise
Knowledge check
PC 192.168.10.10/24 sends to 192.168.20.9 through gateway 192.168.10.1. Which address does it ARP for?
Educational model — not real hardware, traffic or official certification.