Which statement describes how Router Advertisements support IPv6 address configuration?

• A. RA messages inform hosts about network prefixes and the default route.
• B. RA messages assign IPv4 addresses.
• C. RA messages configure DNS.
• D. RA messages locate MAC addresses.

Answer: (A)

Router Advertisements are the mechanism that lets an IPv6 host learn how to configure its address and where to send traffic beyond the local network. An RA can carry a prefix information option, which announces the network’s prefix and its length. When the autonomous-address-configuration flag is set, the host uses that prefix plus its own interface identifier to automatically generate an IPv6 address—this is stateless address configuration. At the same time, the RA provides information about the router’s presence and its lifetime, which lets the host install a default route to forward non-local traffic through that router. This combination directly explains how address configuration is supported without servers handing out addresses.

Routers don’t assign IPv4 addresses via Router Advertisements, so that option isn’t applicable. DNS configuration and the discovery of MAC addresses aren’t the purpose of these advertisements either, so those aspects aren’t described by RA in the same way.