From: Thomas Bridge (tbridge at domain vianetworks.ie)
Date: Thu 11 Apr 2002 - 21:06:18 IST
-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1
One situation where you have to use CNAMES.
Suppose you get a block of say, 128 IP addresses from an ISP (for the sake
of argument, I'll use 192.168.71.0/25).
ISP is probably going to want to assign the rest of the Class C (ie
192.168.74.128/25) to another customer.
Who controls the reverse DNS? Well, currently it's the ISP. They aren't
going to delegate 71.168.192.in-addr.arpa to either customer, as that means
that the customer who doesn't get the delegation has to deal with the other
customer, rather than the ISP. This is clearly ludicrous - after all, would
you want to talk to the likes of Paul to get your reverse DNS sorted out :)
The current hack is documented in RFC 2317. The way around is as follows
(I'm doing this from memory, check the RFC for the recommended practice).
Subdeletgate the zone 0/25.71.168.192.in-addr.arpa to the first customer.
Add records for all the IP address as follows:
n IN CNAME n.0/25.71.168.192.inaddr.arpa.
Customer then adds the right hand side to the zone on his nameservers as
follows:
$ORIGIN 0/25.71.168.192.in-addr.arpa.
n IN PTR server.customer.ie.
There is currently no way to delegated reverse DNS for /25 and smaller
networks without using CNAMES.
Therefore, CNAMEs are required :)
QED.
T.
-----BEGIN PGP SIGNATURE-----
Version: PGPfreeware 7.0.3 for non-commercial use <http://www.pgp.com>
iQA/AwUBPLXsrr6WYZbx1eG3EQJIqwCeLdacN7nx1KRXxXIa4f9zFrwP2VAAoKXU
7lDqo0yiZ4rzhmmEbiLvAvsX
=CV9m
-----END PGP SIGNATURE-----
This archive was generated by hypermail 2.1.6 : Thu 06 Feb 2003 - 13:16:02 GMT