Clients ip addresses ramdomly changing to 10.0.0.. . .. Please assist. 2

[Maritime]

I have a few clients that are suddenly loosing network connectivity. Their ip address are changing randomly to the following 10.0.0.8, 10.0.0.25 etc. Any ideas on what could be happening? I'm currently running virus scans as a first option. If you seen this before, please assist.

 

[Maritime]

On checking my DHCP Server I get the message that "The DHCP Server issued a nac to the client" with the ip addresses listed above. I'm still trying to figure out what's happening. But the problem seems to be with DHCP

 

[JasonDeckard]

If you can, setup a sniffer and see how many different replies you get to DHCP requests. I suspect someone on your network has a DHCP service running that shouldn't be.

http://www.closedsocket.com/

 

[bcastner]

Look for a new hardware device.

You need to be absolutely sure nobody introduced a new DHCP server onto your LAN.

I have this issue all the time were someone connects a wireless router to an office or university lan so that they can wirelessly use their laptop.

Depending on your OS version:

http://support.microsoft.com/?kbid=303351

 

[Maritime]

Hi Guys,

Thanks for the feedback, you were both correct. I was testing another server this morning and apparently DHCP was running on it. I did not realise that. Thanks again.