Re: Phantom DNS server

From: Dilan Weerasinghe (dilanw77_at_hotmail.com)
Date: 08/26/04 

Date: 26 Aug 2004 12:46:41 -0700

"Kevin D. Goodknecht Sr. [MVP]" <admin@nospam.WFTX.US> wrote in message news:<u7FbX92iEHA.2052@TK2MSFTNGP15.phx.gbl>...
> In news:4df8d57a.0408260441.3946cd3a@posting.google.com,
> Dilan Weerasinghe <dilanw77@hotmail.com> wrote their comments
> Then Kevin replied below:
> > Hi NG,
> >
> > We have noticed that several of our PC's suddenly seem to
> > lose their ability to browse the net, connect to our
> > Exchange server etc. Basic troubleshooting showed that
> > although the actual connectivity was there, name
> > resolution seemed to be causing the problem, i.e. we
> > could ping internally/externally by IP address but not by
> > name.
> >
> > Checking the IPCONFIG showed that these machines, which
> > are all set to DHCP, seemed to be picking up a phantom
> > DNS server as opposed to the correct one, e.g.
> > 192.168.1.12 as opposed to 192.168.1.1
> >
> > Rebooting the machines resolves the problem.
> >
> > When we try to ping the phantom DNS server, we do not get
> > a reply. That address itself is excluded from our DHCP
> > range and is not currently being used, so i have no idea
> > why these workstations are picking this same address all
> > the time.
> >
> > Has anyone experienced this before, or have any
> > pointers?? All other settings in IPCONFIG are correct,
> > and we have not made any changes to our
> > infrastructure/architecture recently.
>
> It is possible for your clients to get the DNS address from a Group policy,
> it would not show in the ipconfig /all but when running nslookup you will
> get it.
> You're saying that there is no machine at 192.168.1.12?
> And that the DHCP server is publishing the address of the local DNS server
> 192.168.1.1 and not the IP of the router?
> Are you using DHCP on the server or the router? (if you have a router)
>
>
>
Thanks for the reply.

No, there is no machine at all on 192.168.1.12, and the DHCP server is
configured correctly to give a DNS server address of 192.168.1.1.
We are using a DHCP server that has a different address altogether.

The strange thing is that this switch happens whilst a user is logged
on and has been for a while...not on machine start up or logon.

Any ideas?

Dilan

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