IP Showing in DNS that shouldn't

[rye8261]

On Friday a few people at work said they had trouble getting to the internet. I looked and saw that somehow they got a DNS Server IP that shouldn't be there, our network is a 192.168.X and it was a 172.16.X. So after a simple repair on their connection it would work find. Now more people seem to be having the issue and I can't figure out where it's coming from.

I've triple checked our DHCP server and there are no references to the rogue IP address.

Does anyone have any ideas for me to look at or any suggestions of software that can scan our network and see what services people have running, maybe someone added a server with DHCP or a DNS server and didn't inform me...

 

[GlenJohnson]

Think you hit it already. Sounds like a rouge DHCP server somewhere in there. Anybody bring in a new laptop? Good luck.

Glen A. Johnson
Johnson Computer Consulting

 

[rye8261]

Not that I know of but I don't know how to tell exactly. We have people visiting every day at our office.

Do you know any software to run that will see what services may be running on computers connected to our network?

 

[rye8261]

Another thing I've noticed is this only happens with Windows XP. None of our Vista or 2000 PC's have had a problem.

 

[GlenJohnson]

How many servers do you have?

Glen A. Johnson
Johnson Computer Consulting

 

[rye8261]

There are 11 Servers. This is not coming from any of them. I've triple checked all of them. It must be from a client computer.

 

[lhuegele]

On the machines that are getting the 172 address, do an IPCONFIG /ALL and look for the IP address of the DHCP server that gave them their address.

The only thing I can think of is you have another DHCP server on your network somehow. Do you have any wireless access to your network?

Good luck,

 

[technome]

If you have managed switches, track down the wire by IP


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