TOCICI

How to manage reverse DNS records?

Please use the control panel interface to configure your IPv4 and IPv6 reverse DNS entries.

To establish an rDNS entry, click on the IP address that you'd like to set the value for.

Upon entering a valid1) rDNS entry, the following confirmation message will be shown at the top of your Control Panel interface:

Valid Hostname Characters

The Internet standards for protocols mandate that component hostname labels may contain only:

  • ASCII letters 'a' through 'z' (in a case-insensitive manner)
  • The digits '0' through '9'
  • The hyphen ('-')

No other symbols, punctuation characters, or white space are permitted.

Additional details can be found on Wikipedia, and in O'Reilly's "Dns and Bind, by Cricket Liu and Paul Albitz"2)

Verification of rDNS Entries

Many applications use DNS lookups for security checks. To ensure validity of claimed names, some applications will look up PTR/rDNS records to identify a hostname, and then perform a forward lookup to confirm a match. Failure to find matching forward and reverse DNS mappings is interpreted as a potential security concern.

To address this concern, we follow common FCrDNS practices, by testing each rDNS name for its matching A3) or AAAA4) entry. All that's required by you, is for you ensure there is a valid forward DNS entry in place, prior to configuring your rDNS values.

Additional resources:

1) a matching forward DNS entry must exist
2) ISBN:1565925122
3) IPv4
4) IPv6