Enter IPv6 address or a reveresed ip6.arpa address used for rDNS:
Revers DNS (rDNS) requires you to input the reverse ip6.arpa address of an IPv6 address. This can be difficult and time consuming to do by hand. This calculator will take an IPv6 address and output the reverse ip6.arpa format. Useful for PTR records.

It can also take a valid arpa format IPv6 address and turn it into a correctly formated IPv6 address. This is useful is taking the output of a "dig -x" command for example.