Which IPv6 prefix is used for link-local addresses?

• A. Fc00::/7
• B. 2001::/32
• C. ::1/128
• D. Fe80::/10

Answer: (D)

Link-local IPv6 addresses are used for communication on the local network segment and are automatically configured on every interface. They are not routable beyond the immediate link, which is why devices can talk to each other on the same network without needing a router. The prefix designated for these link-local addresses is fe80::/10, meaning any address that starts with fe80 up to febf is considered link-local. This range is reserved specifically for local-link use and is essential for tasks like neighbor discovery and local address autoconfiguration.

In contrast, fc00::/7 is for unique local addresses intended for private use, 2001::/32 is for global unicast addresses routable on the internet, and ::1/128 is the loopback address. So fe80::/10 is the correct link-local prefix.