Linux Forums unreachable.

Karl Auer kauer at
Mon Feb 22 09:29:16 UTC 2010

On Mon, 2010-02-22 at 00:56 -0800, Ray Parrish wrote:
> I do not think it is a DNS problem, as I used the following Python code 
> to retrieve the ip address of as, and 
> attempted to connect to that ip address with my web browser [Firefox], 
> and was unable to connect.

The browser found the desired site, but could not connect. That suggests
strongly that it is not a DNS problem.

You can completely exclude a DNS problem (or show that it IS a DNS
problem) with three simple steps.

1: Attempt to resolve the problem name using dig.


   If you get back an answer, then the DNS is working for you, and
   the problem is almost certainly NOT a DNS problem.

   If dig does NOT return an answer, then you almost certainly DO have
   a DNS problem.

2: If dig did NOT return an answer, try tracing the DNS lookup:

      dig +trace

   If you get an answer with this, but did not in step 1, then someone
   is caching bad data. There is little you can do about it unless you
   run your own caching nameserver in which case try clearing its cache.
   Otherwise you can wait - but it could be quite a long time; hours or
   even days.

3. Now add an entry for the name into /etc/hosts:

   You will need to be root to do this.

   Does your browser now find the desired site? If yes, it is
   *definitely* a DNS problem. Remember to remove the new entry
   from /etc/hosts before further testing!

How to fix a DNS problem is a bigger question :-)

Regards, K.

Karl Auer (kauer at                   +61-2-64957160 (h)                  +61-428-957160 (mob)

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