DNS64 Server
If you need to use a DNS and you want to perform NAT64 translation using IPv6-Initiated
Communication, you must use a third-party DNS64 server or other DNS64 solution that
is set up with the Well-Known Prefix or your NSP. When an IPv6 host attempts to
access an IPv4 host or domain on the internet, the DNS64 server queries an
authoritative DNS server for the IPv4 address mapped to that hostname. The DNS
server returns an Address record (A record) to the DNS64 server containing the IPv4
address for the hostname.
NAT64 operates on Layer 3 interfaces, subinterfaces, and tunnel interfaces. To use NAT64 on a
Palo Alto Networks firewall for IPv6-initiated communication, you must have a
third-party DNS64 server or a solution in place to separate the DNS query function
from the NAT function. The DNS64 server translates between your IPv6 host and an
IPv4 DNS server by encoding the IPv4 address that it receives from a public DNS
server into an IPv6 address for the IPv6 host.
The DNS64 server in turn converts the IPv4 address to hexadecimal and encodes it into the
appropriate octets of the IPv6 prefix it’s set up to use (the Well-Known Prefix or
your NSP) based on the prefix length. This results in an IPv4-Embedded IPv6 Address.
The DNS64 server sends an AAAA record to the IPv6 host who maps the IPv4-embedded
IPv6 address to the IPv4 hostname.