While in the Master zone your hostname is pointed to an IP address, using the Master Reverse zone allows you to point an IP address to a hostname. The Master/Slave Reverse Zones are available only for premium customers.
Login in your account, click on the DNS zones [Add new] link and click on the Master reverse zone box. The IPv4 zone needs to be in the format 1.0.0.127 for IP 127.0.0.1 and from the drop-down menu need to be chosen in-addr.arpa.
If you prefer to use IPv6, the name of the reverse zone needs to be in the format 1.2.3.4.5.6.7.8.9.0.1.2.3.4.5.6.7.8.9.0.1.2.3.4.5.6.7.8.9.0.1.2 for IPv6 2109:8765:4321:0987:6543:2109:8765:4321 and from the drop-down menu needs to be chosen ip6.arpa.
The reverse zone name for the zone has to be in a specific format. The reverse name starts with your IP address, written backward. If your IP is 1.1.115.125., you need to reverse it to 125.115.1.1. After the zone is created you will be able to add the PTR record(s) pointed to your domain(s). When you create the Master Reverse zone, you need to ask the IP owner to delegate the management of the IP to our servers.
The Slave/Backup Reverse DNS zone is the read-only copy of the DNS records. This means that the DNS records cannot be added directly to the Slave/Backup Reverse DNS zone. The Slave/Backup Reverse DNS zone can receive the updated records only from the Master Reverse zone of the DNS server.
For creating Slave Reverse Zone (Secondary DNS for Reverse DNS zones), you need to Login in your account, click on the DNS zones [Add new] link, click on the Slave reverse zone box, write the reverse zone name as is showed above, enter the Master server IP and click on "Register".
The records can be managed only from the master servers.
The IPv4 zone needs to be in the format 1.0.0.127 for IP 127.0.0.1 and from the drop-down menu need to be chosen in-addr.arpa. The IPv6 zone needs to be in the format 1.2.3.4.5.6.7.8.9.0.1.2.3.4.5.6.7.8.9.0.1.2.3.4.5.6.7.8.9.0.1.2 for IPv6 2109:8765:4321:0987:6543:2109:8765:4321 and from the drop-down menu needs to be chosen ip6.arpa. The master IP can be either IPv6 or IPv4, no matter what is the type of the zone.