PTR Records

[joximu]

a PTR entry points from an ip address to the fqhn (Full Qualified Host Name) of the server.

Only the owner of an ip can create PTR records (or he can delegate this to the customer who uses theese ips) - but in any case you have to caontact your provider where your ispcp server is located or the provider who gives you the ip address for the ispcp server.

Please read a good documentation about dns.
At least http://en.wikipedia.org/wiki/Reverse_DNS_lookup and some links there...

The registrar wants maybe that the ip for the DNS for a domain should fully resolve

/J