Explain IPv6 Neighbor Discovery (ND) role beyond address resolution.

• A. ND handles neighbor reachability, duplicate address detection, router discovery
• B. ND handles routing table maintenance
• C. ND handles IP address assignment
• D. ND handles traffic shaping decisions

Answer: (B)

IPv6 Neighbor Discovery extends how a host on a local link interacts with its neighbors and with routers, not just how it translates a link-layer address. It keeps the neighbor cache healthy by checking reachability with Neighbor Solicitation and Neighbor Advertisement, so a host knows when a neighbor is still reachable and can update or prune entries as needed. It also performs Duplicate Address Detection, ensuring that a newly configured IPv6 address on an interface isn’t already in use by someone else on the same link.

ND also handles router discovery, enabling a host to learn about on-link routers, the default gateway, the MTU of the link, and the network prefix information. Routers advertise these details via Router Advertisements, and a host can actively solicit them to speed up configuration. In addition, Redirect messages allow a router to tell a host about a better next hop for a specific destination, helping optimize local traffic without involving broader routing protocols.

In short, ND provides the mechanisms for reliable neighbor reachability, address safety on the local link through DAD, and discovery of routers and their parameters, which are essential for correct local communication and autoconfiguration. Routing table maintenance and traffic shaping are handled by routing protocols and policy mechanisms, not by Neighbor Discovery; ND supplies the local-link information that those higher-level processes may use.