Link-local address
A link-local address is an IP address valid only on the local network segment it was configured on, never routed beyond it. In IPv6, every interface automatically generates one in the fe80::/10 block defined by RFC 4291, using it for essential local operations like neighbor discovery and SLAAC (RFC 4862) before any routable global address is even assigned. IPv4 has an equivalent mechanism, RFC 3927's 169.254.0.0/16 range, which a device assigns itself via APIPA when DHCP fails, as a fallback rather than a routine addressing scheme. Because link-local addresses aren't globally unique or routable, the same fe80:: address can appear on many different interfaces at once, which is why IPv6 tooling and URLs require a zone index (such as fe80::1%eth0) to say which interface it applies to. AdminKit's guide to IPv6 SLAAC and EUI-64 addressing covers how link-local addresses get generated and used during IPv6 autoconfiguration.
By AdminKit team, Netbase JSC · Updated