Which protocol helps IPv6 devices learn about other devices on their networks?

Which protocol helps IPv6 devices learn about other devices on their networks?

• A. Neighbor Discovery Protocol
• B. Address Resolution Protocol
• C. Internet Control Message Protocol
• D. Dynamic Host Configuration Protocol

Answer: (A)

IPv6 devices learn about other devices on their local network through the Neighbor Discovery Protocol, which uses ICMPv6 messages to perform several discovery and maintenance tasks on the link. For address resolution, a host that needs to send to a neighbor on the same link sends a Neighbor Solicitation to the target’s solicited-node multicast address. The neighbor replies with a Neighbor Advertisement containing its MAC address, letting the sender encapsulate frames for that device. To learn how to reach beyond the local link, the host can issue Router Solicitation; routers respond with Router Advertisements that provide information such as available routers, network prefixes, and default routes. Duplicate Address Detection is also handled here, ensuring a newly assigned IPv6 address isn’t already in use by sending a solicitation and waiting for any conflicting response. This approach replaces IPv4’s ARP, which serves a similar purpose in a different protocol stack. DHCP handles obtaining IP configuration like addresses and DNS servers, not neighbor learning, while ICMP broadly supports control messages and errors, with Neighbor Discovery being its IPv6-specific mechanism for learning about other devices.

IPv6 devices learn about other devices on their local network through the Neighbor Discovery Protocol, which uses ICMPv6 messages to perform several discovery and maintenance tasks on the link.

For address resolution, a host that needs to send to a neighbor on the same link sends a Neighbor Solicitation to the target’s solicited-node multicast address. The neighbor replies with a Neighbor Advertisement containing its MAC address, letting the sender encapsulate frames for that device. To learn how to reach beyond the local link, the host can issue Router Solicitation; routers respond with Router Advertisements that provide information such as available routers, network prefixes, and default routes.

Duplicate Address Detection is also handled here, ensuring a newly assigned IPv6 address isn’t already in use by sending a solicitation and waiting for any conflicting response. This approach replaces IPv4’s ARP, which serves a similar purpose in a different protocol stack.

DHCP handles obtaining IP configuration like addresses and DNS servers, not neighbor learning, while ICMP broadly supports control messages and errors, with Neighbor Discovery being its IPv6-specific mechanism for learning about other devices.