DNS64
DNS64, defined in RFC 6147, is a DNS resolver behavior that lets an IPv6-only client discover IPv4-only destinations through an ordinary AAAA lookup. When a DNS64 resolver receives a query for a name's AAAA record and the authoritative answer contains no AAAA record at all, it instead looks up the name's A record and synthesizes a corresponding IPv6 address by embedding the IPv4 address inside an IPv6 prefix, rather than returning NXDOMAIN or an empty answer the way a plain resolver would. That synthesized address uses either the Well-Known Prefix 64:ff9b::/96 defined in RFC 6052, or a network-specific prefix an operator chooses instead, and it has to match whatever prefix the network's NAT64 translator expects, since DNS64 only manufactures an address for NAT64 to actually route -- the two are designed to be deployed together, and mismatched prefixes between them break the whole path even though each component works correctly on its own. Neither the client nor the destination server needs any IPv6/IPv4 awareness added for this to work; the translation is transparent at both ends.
By AdminKit team, Netbase JSC · Updated