[lug] DNS Problems: Is it me, or is it Comcast?

[David Anselmi]

Michael Deck wrote:
[...]
> Here are the details. On Friday morning I noticed I was unable to ping 
> my remote server (cleansoft.com) by name but I could ping it by IP 
> address (198.49.126.122). This from my home office, which has Comcast 
> "business" cable internet. The remote host is running KRUD FC1 and is 
> authoritative for cleansoft.com.

So your home office can't resolve cleansoft.com.

> I also noticed I could ping the server by name from the host of one of 
> my clients. At first I thought that this was a DNS refresh problem, or 
> maybe an iptables problem, but I think I've convinced myself it isn't 
> iptables.

Your client can resolve cleansoft.com.

> If I put 198.49.126.122 in /etc/resolv.conf as a nameserver, my local 
> problems go away. Emails appear to be reaching me from everywhere except 
> other comcast users.

Apparently your home office DNS cache is broken.  Your name server 
(198.49.126.122) is working fine (as indicated by others' replies).

You can also use dig +trace cleansoft.com. to verify that your 
delegations are right and get you what you expect.

The place to look then isn't on the cleansoft.com NS so forget about its 
zone files and BIND config (which you say you didn't change anyway). 
You need to look at your local resolv.conf and the name servers listed 
there.

Do you understand the difference between a name server resolving names 
for clients (a DNS cache, using recursive queries) and a name server 
resolving names for other name servers (an authoritative name server, 
using non-recursive queries)?

HTH, apologies if I'm confusing, there seems to be a lack of consistent 
terminology when talking about DNS.  But I'll clarify if I can.

Dave