Reverse DNS: Difference between revisions

This setting is found on the control pages under the link to your Login.

 

 

Delegation by NS works by putting your name server in our DNS for each of your addresses. e.g. if you had 217.169.0.0-3 then we would put your name servers for each entry 0.0.169.217.in-addr.arpa , 1.0.169.217.in-addr.arpa,2.0.169.217.in-addr.arpa,3.0.169.217.in-addr.arpa . This would mean you can create 4 separate zone files each of which has to normal SOA records, etc, and a single PTR record with the name for that IP address. This is logically the correct way of doing it as the reverse DNS zone is delegated at each level of control right down to the IP address level. It is rather tedious to set up lots of zone files though, especially if you have, say, 128 addresses.

 

 

Delegation by CNAME is a way to delegate a block of addresses to you so that you only have one zone file to worry about. The way this works is that we put a CNAME record for each address indicating that the answer is found under a different name. We then delegate that different name to your name servers. There are several ways to do this, but we use the system of first-last.restofzone.in-addr.arpa. e.g. if you had 217.169.0.0-3 we would delegate a zone 0-3.0.169.217.in-addr.arpa to your name server(s) and add CNAME entries for each IP, e.g. 1.0.169.217.in-addr.arpa with CNAME to 1.0-3.0.169.217.in-adrr.arpa .

 

 

Auto reverse is a third option that works by filling in a PTR record for each IP4 address and a corresponding forward A record as well so that all of your IP addresses will have a valid reverse entry automatically. This is mainly for customers who are not interested in setting up any reverse entries but need something in place to avoid problems with some servers. If you also use A+reverse records in a domain then your IPs will have two PTR records, both valid.