CIDR example for BIND

Kevin Darcy kcd at daimlerchrysler.com
Wed Jul 28 21:00:31 UTC 2004


Jeff Stevens wrote:

>I'm having a customer that wants to do CIDR reverse lookups but I can't seem 
>to find an example for the subnet x.x.x.x/26 case and the range 
>x-y.x.x.in-addr.arpa. case.  I assume both notations are allowed in a 
>named.conf file?  I'm trying to build a sample named.conf with DB files that 
>can illustrate this using both cases.
>
Well, you can call the container zone anything you wish. Call it 
example.org if you want. named doesn't read any special meaning into the 
zone name. It's just a place to contain PTR records.

>Customer has a partial Class 3 subnet assigned to him: 12.145.185.192 
>through 12.145.185.255.  The reversing DNS entry for his email server 
>(12.145.85.236) is coming from AT&T as 236.192/26.185.145.12.in-addr.arpa..
>
>A link with examples would be great...
>  
>
185.145.12.in-addr.arpa is delegated to tr1.trificient.net, which does 
not appear to have any records for the name 236.85.145.12.in-addr.arpa.

RFC 2317 is of course the definitive place to see how "classless in-addr 
delegation" is accomplished.

- Kevin




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