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Do you support Reverse Lookup DNS (PTR) zones?


Yes, absolutely! Before you can configure a reverse zone, you must first, however, contact the ISP that issued you your IP addresses and have them delegate the IN-ADDR.ARPA or IP6.ARPA records to the name servers we’ve assigned to your account. (You can find these listed in a box on the right side of the DOMAINS tab after you’ve created your first domain). Once this has been completed, you will want to create a new *reverse* zone using the correct in-addr.arpa syntax. Your ISP may want to follow a certain protocol for delegating, so once they have completed the delegation, ask them how you should name the zone.

If you have been delegated a /24, it is fairly simple. For example, if you have been delegated 192.168.5.0/24, your reverse zone would most likely be named 5.168.192.in-addr.arpa.

But for allocations that are smaller (e.g. /25 down to a /32) there are three generally accepted techniques:

  • DeGroot notation
  • RFC 4138 notation
  • RFC 2317 notation

Sometimes your ISP can’t or won’t tell you how to name your reverse zone. In that case, you can use a tool like that at dnsquery.org. Go to that site and perform a reverse DNS query for one of the IP addresses in the range they have delegated to us. This tool will show how it resolves all the way from the root servers down to ours. Before our servers at the bottom of the page you will see exactly what in-addr.arpa zone name they are looking for, so copy that and create a zone named exactly the same. Then, create your first PTR record for the IP address you just tested. Give it a few moments to propagate our network and test again!

If in doubt, please contact us. Setting up reverse DNS can be a frustrating thing. Fortunately, it only has to be done once. Once configured, you can manage it with ease.

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