Reverse Delegation

[phn at icke-reklam.ipsec.nu]

Jim McAtee <jmcatee at mediaodyssey.com> wrote:
> We just started using a new ISP for connectivity at our offices.  They're 
> a reseller of another, national ISP.

> I'm trying to get them to set up delegation of reverse DNS for our 
> network.  I believe the reseller has some access to the larger ISPs DNS 
> systems so that they can set up PTR records or CNAMEs in the in-addr.arpa 
> zones for their customers.  I'm not sure that they can create NS records 
> to delegate subzones, however.

> Instead of them doing a fairly standard RFC 2317 delegation, as we've 
> always done with our providers

> 0-26    IN NS ns1.mydomain.com.
>         IN NS ns2.mydomain.com.
> $ORIGIN .
> 0       IN CNAME 0.0-26.95.104.199.in-addr.arpa.
> 1       IN CNAME 1.0-26.95.104.199.in-addr.arpa.
> 2       IN CNAME 1.0-26.95.104.199.in-addr.arpa.
> etc.

> would the following, without creating a delegated subzone, work just as 
> well, or are there potential problems?

> $ORIGIN .
> 0       IN CNAME 0-officenet.mydomain.com.
> 1       IN CNAME 1-officenet.mydomain.com.
> 2       IN CNAME 2-officenet.mydomain.com.
> etc.

This last method will work well, in addition you will get away 
with only one zonefile (mydomain.com) 

In addition to your normal SOA NS MX & A records add PTR records looking like :

0-officenet   IN  PTR   <name-of-host-using-1st-ip>.mydomain.com.
1-officenet   IN  PTR   <name-of-host-using-2nd-ip>.mydomain.com.


repeat until done.

The nice thing is that grouping A and PTR records together reduces the 
risk of errors.




-- 
Peter Håkanson         
        IPSec  Sverige      ( At Gothenburg Riverside )
           Sorry about my e-mail address, but i'm trying to keep spam out,
	   remove "icke-reklam" if you feel for mailing me. Thanx.