Windows 9x IP Conflicts with W2K DHCP Server 3

[ampaul]

I currently have a single Windows 2000 (SP2)Compaq DL380 server, in a single domain, running: Exchange 2000 (SP1), ISA, DHCP, and Oracle 8.x. In addition to all the apps, this server is also the PDC and is responsible for file and print services. The server/domain is configured for mixed mode to support the nasty Win 9x machines on the domain, in addition to the W2k workstations. All computers in the domain are set to use DHCP. The only static addresses are assigned to printers, the server, and various network equipment.

The problem is: Random Win 9x machines are having IP conflicts with the addresses used within the DHCP IP pool. There are less than 40 computers that receive IP addresses, and the DHCP pool is set to issue 50 IP addresses, so running out addresses is not the issue (I checked the scope). When an IP conflict occurs on any two given win 9x computers, releasing and renewing the IP address with a reboot does not work, the conflict will reoccur on the same two computers, using the same IP address as before the reboot after the computer comes back up. To work around this, as a temp fix to get the users working, I've had to assign a static IP to one of the two conflicting Win 9x computers, with an IP that is outside the DHCP scope. At the end of the work day, I would then reset the changed Win 9x computer to use DHCP again, and the problem would disappear on the two previously affected computers for a while. The bottom line is, the IP conflicts keep reoccurring on other random win 9x computers, and I can't keep up with the problem by using my "work around" and still prevent massive user downtime...

Any help to resolve this issue would be appreciated.

 

[tom11011]

I would first start by completely deleting everything inside of network neighborhood and rebooting. Upon bootup when it finds new equipment etc.. if it asks for the cd, use the cd instead of any cabs on the hard-drive. See if that helps.

 

[grandpubah]

I've seen this many times. Make sure you have all the updates applied to the 9X clients. Several of them address issues with dhcp.

With that few workstations I would consider just hard coding the ip's on the 9X machines. In the long run you will save time.

Jon

 

[ampaul]

Tom11011 - I hesitate to do such a drastic change to a server that has been in production since July 2001 and has had little to no problems. The IP problems have only started occuring within the last 30 to 45 days. No changes have been made to the network or server. I feel that making this sort of change to the server will most likely cause other problems.

Grandpubah - I feel that you're suggestion regarding the updates is the first place to start. However, I have been rather anal about finding and applying all the Win 9x patches that I could find. I may have missed one or two, and so will look into this again. As far as assigning static IP addresses... I would rather make that my last resort to resolve the IP problem, and is why I have made this post to the forum. Hopefully I will find an update for the 9x machines.

 

[brontosaurus]

If I may offer one other suggestion. Try changing the NIC on one of the problem PC's. A fresh MAC registration may solve your problems...

 

[koquito]

Did you try deleting the leases from DHCP manager for all those Win9x computers, and then reboot them? A+, MCP, CCNA
marbinpr@hotmail.com

Keep fighting for your knowledge!

 

[GlenJohnson]

Have you checked your event log on the server? That's a good place to start. Also, since this just started, has the server been re-booted lately. Sometimes that will fix problems for you. Glen A. Johnson
Microsoft Certified Professional
glen@nellsgiftbox.com


"They believe that nothing will happen because they have closed their doors."
Maurice Maeterlinck (1862-1949); Belgian author

 

[ampaul]

Brontosaurus - Unfortunately, I don't have extra NIC hardware to swap in & out of the computers. Also, all of the Win 9x computer have onboard NICs, and placing an additional PCI NIC in a Win9x computer is ususally a hair pulling experience. Last, there are too many Win 9x computers that randomly experience IP conflicts to change out hardware as needed.

Koquito - I have not tried to remove the conflicting lease from the DHCP Manager, and will also try that, in addition to a reboot on the next IP conflict.

GlenJohnson - One of the first items that I checked was the event log on the server. There are some errors in the event log, but they are unrelated to the IP conflicts that are occurring. I checked the uptime on the server, which is currently at 30 days... I don't think that is a very long time for a W2k server to be without a reboot. If my memory servers me correctly, this particular server was up for over 120 days till it was rebooted the last time, and it also did not have any problems prior to the reboot. Rebooting the server has brought to mind the thought of stopping and restarting the DHCP service, which I will do tonight.

 

[CHESTNUTTR]

Any chance you could have introduced a "second" or rogue DHCP source into your system? Things like a new DSL internet access or an unauthorized test DHCP server?

 

[ampaul]

Chestnuttr - I am absolutely positive that there is no other enabled DHCP issuing device on my network... Thanks for the thoughts though.


To All - I think that I may have resolved the issue. I have set the DHCP scope conflict detection attempts to 2. It was previously set to zero. I have also stopped and restarted the DHCP server service after making the change. At this point, there have been no IP conflicts yet today... I'll keep my finger crossed. Thanks for all of the help!