Which two ICMPv6 messages are not present in ICMP for IPv4? (Choose two.)

The first ICMPv6 message that is unique to IPv6 is the Router Advertisement. This message is used by routers to actively inform hosts on the network about the presence of a router. When a router sends out Router Advertisement messages, it provides the necessary configuration parameters that hosts need in order to automatically configure their own IPv6 addresses and routing capabilities. This functionality is essential in IPv6 for stateless address autoconfiguration.

Another important message that is unique to ICMPv6 is the Neighbor Solicitation. This message allows nodes to discover other nodes on the same local link (network segment) and to determine their link-layer addresses. Neighbor Solicitation is crucial for neighbor discovery processes and facilitates functions such as address resolution and duplicate address detection in IPv6 networks.

Both messages are integral to the operation of IPv6 networks and reflect enhancements over the functionalities provided by ICMP in IPv4.