Security Incidents mailing list archives

Re: strange DNS behavior over the last 2 days


From: Chris Wilkes <cwilkes () ladro com>
Date: Thu, 27 Mar 2003 18:18:15 -0800

On Thu, Mar 27, 2003 at 01:06:31PM -0500, steve baker wrote:
For some odd reason, periodically our clients will visit a site, only to 
have a blank page appear as if the site loaded.

What sites?

Nslookup resolves the correct IP address, but ping returns 64.251.66.2 for 
every address that has this problem.  There are NO hosts files on these 
machines and regardless of which DNS server we point them to, the same 
problem occurs.

What DNS servers are you asking?  Your own?  If so, I would take a look
at the logs to see:
-what query came in
-what server your DNS server asked for the correct response
-what query your DNS server sent to that server

The problem occurs intermittently as well, which makes it even harder to 
pin down.  Some sites previously affected will be accessible and new sites 
not affected suddenly have the same problem - but they eventually clear up 
in just about 10 minutes.

Very strange.  Has anyone heard or seen this before on a network running 
windows nt 4 DNS server with nt/2000 clients?

Does NT4's DNS server have any sort of logging on there?  You might want
to look at that.

What DNS servers do you have listed for your clients?  You can do a
"ipconfig /all" to find out what ones are in there.

You can also install http://www.ethereal.org on your Windows box and
find out what queries it is sending out.  You might think your asking
for the DNS entry for "example.com" but really you're asking for
"example.com.mylocaldomain.com"  I have a feeling that could be your
problem.

Chris

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