Which ICMPv6 messages are used by IPv6 Neighbor Discovery Protocol for address resolution and router discovery?

• A. Time Exceeded
• B. Neighbor Solicitation, Neighbor Advertisement, Router Solicitation, Router Advertisement
• C. Echo Request/Reply
• D. Redirect

Answer: (B)

IPv6’s Neighbor Discovery Protocol uses four ICMPv6 message types to handle both address resolution and router discovery. For address resolution on the local link, a node sends a Neighbor Solicitation to the target’s address, and the target replies with a Neighbor Advertisement that includes its link-layer address. For router discovery, a host can send a Router Solicitation to all routers on the link, and routers respond with Router Advertisements that announce their presence and provide network parameters like prefixes and configuration. Other ICMPv6 messages exist for different purposes—Time Exceeded for error conditions, Echo Request/Reply for reachability tests, and Redirect for steering a host to a better next hop—but they are not used for the core discovery processes described.