RFC 1884: “IP Edition 6 Addressing Architecture” makes use of that phrase for a few bits at the conclusion of an IPv6 address. (The amount of bits appeared to change in certain distinctive examples, but this identifier was usually based upon the MAC-48 tackle of a network card.) As for https://trentontgowc.plpwiki.com/5928675/whats_my_ipv4_can_be_fun_for_anyone