Link-local address

In computer networking, a link-local address is a network address that is valid only for communications on a local link, i.e. within a subnetwork that a host is connected to. Link-local addresses are typically assigned automatically through a process known as link-local address autoconfiguration,^[1] also known as auto-IP, automatic private IP addressing (APIPA, specific to IPv4), and stateless address autoconfiguration (SLAAC, specific to IPv6). While most link-local addresses are unicast, this is not necessarily the case; e.g. IPv6 addresses beginning with ff02: (ff02::/16), and IPv4 addresses beginning with 224.0.0. (224.0.0.0/24) are multicast addresses that are link-local.

Link-local addresses are not guaranteed to be unique beyond their network segment. Therefore, routers do not forward packets with link-local source or destination addresses.

IPv4 link-local unicast addresses are assigned from address block 169.254.0.0/16 (169.254.0.0 through 169.254.255.255). In IPv6, unicast link-local addresses are assigned from the block fe80::/10.^{[2]: 2.4 [3]}