NAT64 is a method for allowing IPv6-only clients to connect to IPv4-only servers
NAT64 is a method described in RFC6147 which through a variant of NAT that translates between IPv4 and IPv6 will allow IPv6-only clients to reach IPv4-only servers. Often used in conjunction with DNS64. But can also used by itself by creating authoritative AAAA records or in a 464XLAT setup.