ARP
Address Resolution Protocol
Maps IP addresses to MAC addresses on a local network; spoofable for on-path attacks.
ARP resolves a known IPv4 address to the MAC address needed for delivery on a local segment, caching results to reduce repeated broadcasts. The protocol has no authentication, so an attacker can send forged replies in ARP poisoning or spoofing to associate their MAC with another host's IP, enabling on-path interception. Defenses include dynamic ARP inspection and static entries. Note that IPv6 does not use ARP; it relies on Neighbor Discovery Protocol instead, a common point of confusion.
Address Resolution Protocol: maps an IP to its MAC on the local network (spoofable, hence ARP poisoning).
Looking ARP up is step one. Getting tested on it is step two.
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