Networking · Protocols
ARP
Address Resolution Protocol maps IPv4 addresses to MAC addresses within a local broadcast domain.
FoundationalUpdated 2026-09-01
Overview
A host broadcasts 'who has this IP?' and the owner replies with its MAC address, which is then cached. There is no authentication in ARP, so any host on the segment can answer for any address.
That design gap enables ARP spoofing and on path attacks. Dynamic ARP Inspection, tied to DHCP snooping bindings, is the standard switch level mitigation.