# Address Resolution Protocol (ARP) ![[Address Resolution Protocol - Wikipedia#^crjb6v]] ![[Address Resolution Protocol - Wikipedia#^2j5nmw]] ARP is a protocol used in conjunction with IPv4. IPv6 uses [[NDP|Neighbor Discovery Protocol]] instead. ## Placement on the Layer Stack ![[Address Resolution Protocol - Wikipedia#^eu0gto]] One could argue that ARP is a [[Link Layer]] protocol because it is used to communicate with adjacent nodes (nodes within the current network). However, it also requires knowledge of [[Internet Layer]] concepts like the IP address to facilitate IPv4 so it could be said it's part of the internet layer as well. ^7z7e9z ## Security Concerns ![[Address Resolution Protocol - Wikipedia#^fr79az]] Lack of authentication opens the door to two related attacks: ARP Poisoning and ARP Spoofing. ![[ARP Poisoning What It Is & How to Prevent ARP Spoofing Attacks#^iclkdl]] ![[ARP Poisoning What It Is & How to Prevent ARP Spoofing Attacks#^o6pdgq]]