There is an RFC related to this. https://tools.ietf.org/html/rfc6144 which speaks of IPv4-translatable addresses: IPv6 addresses to be assigned to IPv6 nodes for use with stateless translation. They have an explicit mapping relationship to IPv4 addresses. A stateless translator uses the corresponding IPv4 addresses to represent the IPv6 addresses. A stateful translator does not use this kind of addresses, since IPv6 hosts are represented by the IPv4 address pool in the translator via dynamic state. ... View more