DHCP server ignored occasionally

[spacerabbit]

Hi,
There are two PC's with windows Server 2003 on my network, and we have a newly installed linux gateway, which has DHCP set up on it.
The problem is, is that every morning when I come into work, a few PC's have attempted to obtain new leases, and have been granted them from either of the Server 2003 PC's (setting the gateway and dns to the ip of that server)..
I have uninstalled the DHCP Server services from both PC's, I have also performed a scan for rogue DHCP servers, which only finds the correct one (linux box)..
If anybody has some suggestions as to what is causing this to happen, your help with be greatly appreciated.
Thanks

 

[dtrtel]

What does "ipconfig /all" show as the IP address of the DHCP server? If still the old DHCP server(s), then try to "ipconfig /release", followed by "ipconfig /renew". Then re-examine "ipconfig /all".

If that doesn't fix it, as a long shot, statically assign an IP to the PCs that are having trouble and then reboot.

Then put them back to DHCP assignment and see if the problem goes away. Sounds crazy, but sometimes the unusual has to be done in Microsoft networks.

--jeff

http://linkedin.com/in/JeffLynch

 

[GlenJohnson]

Who's running the dns services? DHCP and DNS are different animals.

Glen A. Johnson
If you like fun and sun, check out Tek-Tips Florida Forum
Buckle up, it works<---Click here.

 

[spacerabbit]

Jeff -
Usually to fix the problem, I disable/re-enable the LAN device, which I would gues is the crude equivalent to what you suggested.. Some times it works right away, sometimes I have to repeat the process 2 or 3 times before it is assigned the correct details.
The two 2003 PC's are .200 and .111 on my network - when an invalid lease is given, it will assign the gateway and dns server to .200 or .111, also saying that .200 or .111 granted the lease..
Will try what you suggested, unfort because the problem is so sporadic, I can't tell straight away if it worked - This morning there were no problem PC's to test on!
Thanks very much
Greg

Glen -
I realise the difference between DNS and DHCP..
.200, one of the 2003 machines is running the internal DNS server
Greg

 

[dtrtel]

Greg,
I think you may be onto something. I assumed the DHCP client lease issues were on workstation PCs not server PCs. Sorry for my possibly incorrect assumption. There would have to be a very strong compelling reason for me not to statically assign parameters to servers on any network. Not to say never, but rather, can we risk the potential instability unless we really, really, really have to.

99% of the time, I set my clients' networks up with a DHCP server, but only for portable devices (like laptop or VPN remote access, so I can get an IP/Mask/Gateway/DNS/Wins/etc, in case I don't have it written down and closely accessible). I lose some billable hours, but only because things are way more stable, and the customer is happier and I become the "hero" <haha>. The interactions between AD/DNS/DHCP is one of the problems I frequently find in windows networks, especially on a new client site I may take over from a previous consultant who didn't take time to plan the IP address map for the network.

Management needs to see this as a relatively small investment in time, but with a big payback, even for rather large networks. For really big networks, geographically dispersed, OK, maybe DHCP makes sense for the workstations but not servers without a very strong reason. Stepping down from my soap box now, but it works for me.



--jeff

http://linkedin.com/in/JeffLynch

 

[spacerabbit]

Jeff -
All the servers have static IP's, and most of the workstations are on DHCP..
I suppose we could statically assign all PC's an IP, originally we had two gateways and the lines were quite unstable and we had to do a lot of switchovers, but now there is only one, so I guess if it gives more troubles, thats the way to go!
Thanks again
Greg

 

[dtrtel]

The two 2003 PC's are .200 and .111 on my network - when an invalid lease is given, it will assign the gateway and dns server to .200 or .111, also saying that .200 or .111 granted the lease..<snip> I can't tell straight away if it worked - This morning there were no problem PC's to test on!

I think your troubles are over now, but if you want to wear a belt and suspenders, verify that DHCP is infact uninstalled and the service is not running on your servers (.200 and .111).


--jeff

http://linkedin.com/in/JeffLynch