In IPv6, which statement correctly describes how link-local addresses are used?

• A. They are globally routable.
• B. They are used for neighbor discovery and essential control plane communications on the local link.
• C. They must be unique across the Internet.
• D. They are only used for multicast communication.

Answer: (B)

Link-local addresses in IPv6 are meant to work only on the same physical or logical link. They provide the addressing needed for neighbor discovery and other essential control-plane communications on that local segment, such as the ICMPv6 messages used to find and talk to neighboring devices and routers. Because their scope is limited to the local link, they are not routable beyond that link, so they don’t have to be unique across the Internet. They are unicast addresses (fe80::/10), not multicast, which is why they’re not used for multicast communication themselves. These addresses are typically auto-configured and serve as a reliable way for devices to discover each other and perform on-link setup and maintenance before any globally routable addresses are in use.