See: Automatic Private IP Addressing (APIPA)
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, also known as auto-IP, automatic private IP addressing (APIPA, specific to IPv4), and stateless address autoconfiguration (SLAAC, specific to IPv6).
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. While most link-local addresses are unicast, link-local multicast addresses also exist, with addresses beginning ff02: (ff02::/16) in IPv6, or 224.0.0. (224.0.0.0/24) in IPv4.
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.