[SWLUG] Reverse DNS lookup problem

[justin at discordia.org.uk]

On 14 Nov, Ash Whitney wrote:
> I co-own a Red Hat Linux 6.2 server, and reverse DNS lookups on the server
> are failing (forward DNS lookups are ok). Consequently, some mail is being
> bounced back to me. Being a Linux virgin it's difficult for me to resolve
> this issue, especially given the lack of support I get from the server's
> administrators - Farcehosts in Gloucester.
> 
> Neil mentioned that some of you had kindly helped by pointing out that
> Fasthosts, rather than myself, were responsible for our server's reverse DNS
> entry. I put this to Fasthosts, and was told that they had done this. I then
> asked if they could advise on resolving the problem, and was given a
> categoric 'NO'.
> 
> Can anyone point me toward a specific file/s that need configuring for
> reverse DNS lookups to be performed on our server. So far, I've only found a
> file called named.conf.
The things that need configuring are not on your server.
Your server is not automatically given control of its reverse dns, that
is the job of the owners of the IP block, and indeed giving control of a
single, or small chunk of addresses like that is often far more effort
than anyone will be bothered to go to.

Only your ISP, the ones that own the IP addresses, can arrange to setup
the reverse-dns, and there is nothing you can do about it except to bug
them.

Having a quick investigate, going by the domain names you are using, i
would guess that (one of) your ip address is 213.171.197.219

$ whois 213.171.197.219 at whois.ripe.net

Reveals that this IP address is indeed in a chunk allocated to Fast
Hosts.

$  dig 219.197.171.213.in-addr.arpa ptr
(asking for the reverse dns record for your machine)
Indicates that Fasthosts have not just failed to setup your one IP
address, but have failed to get control of the entire block!
As the chain of query stops at RIPE and has not even been forwarded as
far as a fasthosts server.

In fact, of that chunk of 32 * 256 IP address blocks assigned to them by
RIPE, they only have the first TWO sections delegated, plus one higher
up. so 213.171.192, 213.171.193, and 213.171.216 address may have
correct reverse-dns, but everything else they control, does not.


You need to nag them again to go and check _properly_ this time, failing
that the only way to fix this is to move to a different hosting service
with someone more competant.

Oh, and ask them if they need some Consulting on how to run internet
services ;)

Justin
caederus.com