Comments on: IP Conflict

By: Tristan Ruhling

Tristan Ruhling — Thu, 04 Feb 2010 16:24:16 +0000

amazing stuff thanx

By: cgarcia26c

cgarcia26c — Thu, 17 Jan 2008 18:49:46 +0000

Thank you guys for your help, the problem was actually that the dchp database was corrupted and therefore giving out the same ip to different computers, after reconciling the dchp database and then verifying it, the problem was solved, and just fo fun I added some reservations to the scope just to make sure that does not happen again.

Thank you all again for your input.

CG._

By: squashjunkie

squashjunkie — Thu, 17 Jan 2008 16:19:53 +0000

Made a hash of my post, so here it is again……
There is the possibility of nic cards having the same mac address, but this will have been changed by someone after the laptops have left the manufacturers. You can check the mac address by typing “ipconfig /all” in a dos box, and make sure they are not duplicate.
If they are, get the following tool
http://tmac.technitium.com/tmac/index.html
which is a freeware app allowing you to change the mac address of either of the two machines.

Importantly though, check the DHCP configuration on your server / router. Making sure both the
reservation time in the DHCP configuration and that ip’s are not being “released” from the client ahead of time (this can happen when there are drift between the clocks of the server and client) should make sure the problem doesn’t re-occur.

By: squashjunkie

squashjunkie — Thu, 17 Jan 2008 16:05:57 +0000

There is the possibility of nic cards having the same mac address, but this will have been changed by someone after the laptops have left the manufacturers. You can check the mac address by typing “ipconfig /all” in a dos box, and make sure they are not duplicate.
If they are, get the following tool

which is a freeware app allowing you to change the mac address of either of the two machines.

By: tbitner

tbitner — Thu, 17 Jan 2008 14:10:48 +0000

Try putting a PCMCIA nic in one of the laptops and see if it fixes the problem. Use that one as your primary and disable the other one.

By: chazbrown

chazbrown — Thu, 17 Jan 2008 14:00:53 +0000

Firstly, it is impossibole for two devices to have the same MAC address as it is assigned by the manufacturer and is not ‘configurable’ by the end user. Secondly, it is ‘supposedly’ impossible for a DHCP server to assign two like IPs on the same network.

I am unsure of exactly what to check and my head is ‘spinning’ at the possibility. However, one easy way around this, especially on a small network, is to simply use static IPs. As you are the one assigning them, it would stand to reason that they would never conflict.

The first thing I would check in this case is the network set up. You have a configuration issue somewhere. I am guessing that one of the laptops has a different domain setting or something. I have no idea how the DHCP server could assign 2 like IPs at the same time otherwise.

HTH
Owen