We require that a matching “forward resolving” A record be configured prior to configuring a reverse DNS entry or “PTR” record.
For example, if you own the IP address 192.168.44.123 and want to configure the reverse DNS address of ‘myserver.example.com’ an “A” record pointing ‘myserver.example.com’ to ‘192.168.44.123’ must first exist before the reverse DNS address can be configured.
This is required to prevent “spoofing” reverse DNS addresses. Without this protection it would be possible to create a reverse DNS address of ‘microsoft.com’ even though you do not control this domain.
Please note that it may take to 24-48 hours for an “A” record to fully propagate throughout the global DNS system so if you have just recently added the matching “A” record it may take some time before our system recognizes your change and allows the reverse DNS entry to be established.