IPv6
NAT64 and DNS64
How an IPv6-only device reaches an IPv4-only server: DNS64 makes up the address, NAT64 translates the packets.
An IPv6-only network still has to reach IPv4-only servers. DNS64 answers an AAAA query for a name that has only an A record with an address it makes up: the IPv4 address in the last 32 bits of a NAT64 prefix, often the well-known 64:ff9b::/96 (10.0.2.11 becomes 64:ff9b::a00:20b). That prefix is routed to a NAT64 translator, which rewrites each packet's IPv6 header as IPv4 and the answers back. Stateful NAT64 keeps a table of flows and puts many IPv6 clients behind one IPv4 address, like NAT for IPv4. The made-up records do not pass DNSSEC validation, and programs that use IPv4 literals need 464XLAT on the client.