IP Conflicts

[kjonnnnn]

We are using DHCP. Periodically a user will get a message that there is an IP conflict. But the conflict it with itself.

For example ComputerA has the IP, 29.29.0.136 showing up in winipcfg.
DHCP shows that ComputerA has the IP 29.29.0.136.

Even if I release the IP, shutdown the computer, then delete the lease from DHCP, when the computer comes back up it still says that there is a conflict with 29.29.0.136 (which is its own address)


What gives? (I've even changed the lease length time, but that didnt work.)

 

[dirtyhat]

Which operating system is the conflicting system running?

 

[kjonnnnn]

The server is on NT 4.0, the desktop is running Win95

 

[DaveGoTech]

If you have any network switches installed, try switching them off/on.

 

[kjonnnnn]

No switches. Just Hubs.

 

[mercenary]

are you running a WINS server?

 

[kjonnnnn]

Yes. One WINS server.

 

[dirtyhat]

From previous Cable modem support. I have seen the same thing with clients that were running Windows 95 version A. They were actually conflicting with their own NICs. $35 an hour Microsoft phone support resolution : UPGRADE

 

[kjonnnnn]

We running 4.0 and 2000

 

[dudue]

Are you connecting directly to internet ?

 

[Kjonnnn]

We do have a firewall if thats what you mean....
But was happending before and after we added the firewall.

In fact again it happened again. A user got a message that there was an IP conflict. The number was the number leased to that computer. I released the number from the computer and shut it down. I deleted the lease in the DHCP server. When it booted up, it got the same conflict message.

I gave the computer a number not in the DHCP scope and it works fine.

 

[Packeteer]

The message should state that another computer has the IP address of the local system. It should identify the hardware NIC address of the device that has the same address...

When your computer boots up, it should do a duplicate IP address test (ARP). If another device has the same address and answers, the error message appears.

Can you assign a different IP address?

 

[Kjonnnn]

A user got a message that there was an IP conflict. The number was the number leased to that computer. I released the number from the computer and shut it down. I deleted the lease in the DHCP server. When it booted up, it got the same conflict message.

I gave the computer a number not in the DHCP scope and it works fine.

 

[Warped]

Hi

Windows does have a problem releasing it ip address but of course it is intermitten. If you run winipcfg on the wkstn that won't release the address, force a release and then do a renew. If that doesn't work then First thing to do is redo your class of ip addresses to hand out. Leave about 10 or so address out of your DHCP range.

Once done then find the wkstns that cause conflict, the one wkstn that has had the address over its lease, simply put a static address (the one outside your range of address that dhcp uses) in and reboot. Once rebooted try the other wkstn. If that is fixed. then a few days later go back and set the static address to dynamic. That will usually work.

My only question is what OS is the wkstn running that is not releaseing the ip address? There is a fix that will most likely cure the problem but only as a last resort.

Vaughn

 

[Kjonnnn]

The Service is NT40. The client OS's are 95, and NT.

The problem is that the IP in conflict with itself.
Once again here's the example. Workstation A (10.10.10.10.)receives an a message its IP address is in conflict with another. There is no other machine is using the IP address. 10.10.10.10 is shown to be leased to Computer A, yet it gets the conflict message.

Can release them on the client and the server, but still will get a conflict message. And as suggested I can even give it a manual IP, but whenever I put it back on DHCP, it comes up in conflict with itself again.

 

[Sleet]

Try the WINS Server look for a dead entry of the problem ip address and remove it. Not entirely sure this is the problem but it is worth a try..

 

[Warped]

Hi

Well then put a static address in and see if that clears it up. Again what OS is the wkstn running? win95 , 98, ME...etc...

Vaughn

 

[Kjonnnn]

Thanks but thats the easy stuff. We've done all that including starting WINS from scratch... THanks though.

 

[ryanl]

We had this problem on Windows 95 machines a while back. After we loaded the Winsock 2.0 update, the problem disappeared:

http://www.microsoft.com/windows95/.../s_wunetworkingtools/w95sockets2/default.asp?

 

[Kjonnnn]

I think we figured it out.

A user, unbeknownst to us, had installed Windows 2000 Advanced Server on this computer, and was running WINS, DHCP you name it. It become a problem with we put in a firewall and changed the internal IP scope (except on his which we did not know about). We shut him down and everythings seems back to normal.

My boss won't let me take him out back either....

Hummmfph... know it all users.