[lug] DNS problems

[Nate Duehr]

Couple more ideas...

Look at /etc/nsswitch.conf and make sure something didn't change that to
tell the machine to not use DNS.
Make sure nscd isn't loaded and running -- it could be "in the way" somehow
or misconfigured.

:-)

Tkil's note about checking the servers manually with dig or nslookup is
valid.  Is there a NAT firewall, ipchains or iptables running on the machine
itself?

You also may want to get low-level with tcpdump and see if it's actually
making DNS query requests and where they're going.

tcpdump -n port domain

Or similar, would do it.  Don't forget the -n if DNS isn't working!  ;-)
Start the tcpdump and then ping something you know you've never been to from
the machine.  You should see something like this:

22:44:13.599117 216.17.141.165.53 > 202.84.198.59.53:  16337 A?
yaddayadda.com. (32)
22:44:13.891933 202.84.198.59.53 > 216.17.141.165.53:  16337*- 1/2/2 A
194.200.132.34 (126)

(To paraphrase a famous Dilbert, the conversation above ammounts to: "You've
got A records?  You must be one of those uppity BIND servers!   Here it is
kid, get yourself a bigger cache.")

--
Nate, nate at natetech.com

> -----Original Message-----
> From: lug-admin at lug.boulder.co.us [mailto:lug-admin at lug.boulder.co.us]On
> Behalf Of J. Wayde Allen
> Sent: Tuesday, April 02, 2002 12:49 PM
> To: List: Boulder Linux User's Group
> Subject: [lug] DNS problems
>
>
>
> Last week my wife started working to upgrade her aging copy of KRUD, and
> ran into a problem with DNS.  She is using KPPP to create a dialup
> connection.  This seems to work in the sense that the modem dials, she
> gets a connection with the ISP, authentication seems to work OK, and PPP
> evidently gets started.  After that though, she isn't able to connect to
> anything.
>
> I took a look at things, and it seems that for whatever reason her system
> is not able to find the DNS servers.  At first I was a bit surprised that
> the resolv.conf file was empty, but once KPPP dials the modem and connects
> it copies the correct nameserver entries into the file.  I was able to
> connect to some known machines using raw IP addresses, and creating an
> entry for one of these in her host table solves the problem for that one
> machine.
>
> So ... any suggestions about what I should have her check next?
>
> - Wayde
>   (wallen at lug.boulder.co.us)
>
> _______________________________________________
> Web Page:  http://lug.boulder.co.us
> Mailing List: http://lists.lug.boulder.co.us/mailman/listinfo/lug
>