The majority of Internet content is currently available only on IPv4. While waiting for migration of content to IPv6, IPv6 end users also need a way to access these services on IPv4. NAT64 and DNS64 provide this service.
NAT64 and DNS64 are used by Service Providers in addition to other methods such as DS-Lite to provide IPv4 content to IPv6 end users.
Service Provider NAT64 and DNS64 solution
The IPv6 end user's DNS requests are received by the DNS64 device, which resolves the requests.
If there is an IPv6 DNS record (AAAA record), then the resolution is forwarded to the end user and they can access the resource directly.
If there is no IPv6 address but there is an IPv4 address (A record), then DNS64 converts the A record into an AAAA record using its NAT64 prefix and forwards it to the end user. The end user then accesses the NAT64 device that NATs this traffic to the IPv4 server.