So I have set up following DNS records in ISPConfig3. Everything else works except PTR, can anyone tell me what exactly is wrong with PTR entries? All lookup tools say reverse DNS does not exist for our IP.
And you are sure that your server is authoritive for the PTR? PTR record have to be created normally in the DNS server of the provider that assigned you the IP address. If you want to add a PTR record, you have to craete a in addr arpa zone for it instaed of adding them to the zone of the domain.