Which protocol replaces ARP in the IPv6 networking model?

In the IPv6 networking model, the Neighbor Discovery Protocol (NDP) is responsible for replacing ARP (Address Resolution Protocol) which is used in IPv4 networks. NDP operates on top of the Internet Control Message Protocol (ICMPv6), which provides functionalities such as discovering other network devices, determining their link-layer addresses, and maintaining reachability information about the paths to active neighbors.

NDP encompasses several functions that were traditionally handled by ARP, including address resolution, neighbor unreachability detection, and router discovery. By utilizing a more comprehensive protocol, IPv6 improves upon the limitations of ARP, leading to a more efficient exchange of operational information necessary for network communication. The presence of protocols like ICMPv6 is essential for enabling NDP to function effectively, but it is NDP itself that specifically handles the tasks that ARP used to perform.

Protocols like ARPv2, while they might sound plausible, do not exist in the context of IPv6, and Multicast DNS (mDNS) serves a different purpose, relating to service discovery rather than address resolution. Thus, NDP is recognized as the direct replacement for ARP in the IPv6 framework.