is is able to setting up DNS server reverse lookup with DynamicIP?

Chuck Swiger cswiger at
Fri Jul 13 18:56:29 UTC 2007

On Jul 13, 2007, at 10:44 AM, Dan Casey wrote:
>>> I'm using dynamicDNS, so I will able to specify the forward *AND*
>>> reverse lookups?
>> No.  Reverse lookups are controlled by whoever owns the IP delegation
>> for the netblock in question, and they are not going to configure PTR
>> records for dynamic IPs.  If you want to have reverse lookups you
>> control, you'll need to get static IPs.
> Slight correction.  To do what you want, you will need to get a static
> ip.  Then you can request your isp (or whoever owns the ip block) to
> setup the PTR record for you.

That's not really a correction.  :-)

If you get a single static IP, for example, normally the ISP or  
netblock owner will not delegate that, but are willing to setup a PTR  

If you get a larger static netblock, especially a /24 or larger, then  
your ISP can delegate reverse DNS to nameservers you run, and thus  
you can set up and change the reverse lookup results at will without  
needing your ISP to make PTR record changes.  See 
rfc/rfc2317.txt about "Classless IN-ADDR.ARPA delegation" for the  
deal with regard to delegation of smaller netblocks than a /24.


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