Moving from fixed ip to DHCP problem

I have installed some dhcp software on a machine in a small subnet and to test it, have changed another from fixed ip to dhcp.

The problem is that it refuses to change its ip and keeps the static one.

i have restarted the machine, run ipconfig /renew and ipconfig /release, but after a second restart, still the fixed ip is there (it is not in the dhcp scope, so no accidental confusion).

The properties of the lan connection are all dhcp with no addresses specified anywhere.

Does it just mean that the dhcp server isn't issuing addresses so the computer reverts to the previous settings?

Any help gratefully received.

 

What IP address did you get? I don't think the computer can revert to the previous settings.

If you computer has more than one NIC, you need specify the adapter when you apply ipconfig command. If you have done so or your computer only has one NIC. I prefer the problem is on your DHCP server.

 

Expose "phantom" & "ghost" devices in Device Manager:
http://support.microsoft.com/default.aspx?scid=kb;en-us;315539

Then under Network Adapters, remove all greyed-out devices. (Leave any "Mini" logical adapters).
Reboot.

Then configure the network adapter to your choice of DHCP or static.

 

Thanks for the replies. I have tried removing phantom devices but there were none to remove.

I only have one NIC in the machine so no conflict there. It is a basic small form factor compaq in standard trim, no unusual bits at all.

I have tried changing the settings from DHCP to a different fixed ip and back again, but the original fixed still applied.

Clicking on "Repair" in the LAN properties has no effect,

maybe something in the registry?

Really stumped with this one

 

I'd try another PC as well, to try to isolate the problem further.

 

Found it - should have looked more closely.

We have a VOIP system and one of the phone routers has DHCP on it for the phone company to test their system. It should have been turned off when not in use. I phoned our phone suppliers and they switched it off remotely.

It was just a huge coincidence that the first address in their scope matched the fixed ip of the machine.

All works well now and thanks for your replies.

 

Lucky indeed, as the issue can be an obscure one.

Some help:

DHCP Troubleshooter:
http://technet2.microsoft.com/Windo...5605-4a19-89ef-8762cdcdc7ad1033.mspx?mfr=true

Using Netsh.exe
http://support.microsoft.com/?kbid=303351