Which of the following IPv6 addresses is a link-local address ?

In IPv6, link-local addresses use the prefix FE80::/10 . These addresses are automatically generated or configured for communication on the local link only and are not routed across Layer 3 boundaries. Therefore, among the given options, FE80::FA63:DBFF:FE9E:10 is the correct link-local address, making option C correct.

Options A and B belong to the Unique Local Address (ULA) space, which uses the prefix FC00::/7 . These addresses are intended for private internal IPv6 networks, somewhat similar in purpose to private IPv4 address ranges, but they are not link-local addresses. Option D , which starts with 2001::, is a global unicast address , used for routable communication across IPv6 networks. HCIA-Datacom teaches that link-local addresses are essential in IPv6 because they are used for functions such as neighbor discovery, router discovery, and routing protocol communication on the local segment. Even when a device has global unicast addresses, the link-local address still plays an important role in normal IPv6 operation and protocol adjacency establishment.