If your IP range is a /28 or smaller, the PTR is not set by you. You may, however, request a custom PTR for your IP addresses by opening a Support Ticket with us. Please list the IP addresses you would like the entries to be made for in addition to the entries you would like assigned.
Customers with /27 or larger IP ranges may request their reverse-DNS to be delegated to their nameservers. Please open a Support Ticket and provide your IP range and the hostname of your nameserver so that we may enter that into our master nameservers.