PC1, PC2, and Router R1 all connect to the same VLAN and IPv6 subnet. PC1 wants to send its first IPv6 packet to PC2. What protocol or message will PC1 use to discover the MAC address to which PC1 should send the Ethernet frame that encapsulates this IPv6 packet?

(A) NDP NS
(B) NAT
(C) DHCP
(D) ARP

NDP NS is the correct answer.

PC1 needs to discover PC2’s MAC address. Unlike IPv4, IPv6 does not use ARP, instead using NDP. Specifically, PC1 uses the NDP Neighbor Solicitation (NS) message to request that PC2 send back an NDP Neighbor Advertisement (NA)

NS — Neighbor Solicitation is a message that sent by a node to determine the link-layer address of a neighbor, or to verify that a neighbor is still reachable via a cached link-layer address. NSes are also used for Duplicate Address Detection (DAD).

NA — Neighbor Advertisement is a message that sent in response to an NS message. A node may also send unsolicited NAs to announce a link-layer address change.