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Windows NT4.0 DHCP

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by tomsal 1 view

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We just setup an old NT4.0 SP6a server to be our DHCP server for our company.

That vast majority of clients are Windows 98SE, with a smidge of XP Pro and Windows 2000 Pro here and there.

For whatever reason, and that's the point of this question -- I don't know the reason, even though we are configured for DHCP I am still having users getting IP conflicts.

Each machine was individual set to be a DHCP client by the MIS department, so I know that was done correctly. I also know the range that is dynamic is specific to the client machines; in other words I have verified my static addresses with switches, servers and printers.

Anyone have ideas on this? Isn't DHCP's purpose to keep list of valid IPs -- why then is it still assigning non-unique IPs to my clients, causing them IP conflicts?

Thanks for any help.

Obviously I'm looking for how to resolve this too not just why. :)

10 replies

by tomsal

I don't know if the link posted was supposed to take me to a specific solution, all that shows up is the Microsoft Help and Support Center. In that case, if the implication is to just search Microsoft knowledge base - I already went down that avenue and couldn't find anything that helped the issue I am having.

by sgt_shultz

so you are saying you verified that the dynamic addresses are out of range and definitely won't conflict with the static devices? i would consider making the devices that need static address dynamic also but preallocate their ip address in the dhcp server. it is easier to administer i think as is all there in one place. is your network small enuf that you could try this: shutdown all clients. start up one by one and do ipconfig /release /renew. maybe make a note of the address it gets in case we decide we wish we knew it later. maybe everything is fine but old dynamically assigned ip addresses haven't had lease expire yet. /release /renew will force them out. there is no black magic as far as i know. if you have a conflict something else has got that address...maybe it is a laptop coming and going off the network...

by joseph moore

Yes, DHCP does keep track of what IP address it assigns to what MAC address. You can open the DHCP Manager and look at what it has done.
But, if you are getting IP conflicts, then I would think that not all of the client machines are set to DHCP. Your "MIS department" did this, but have you checked?
I am the type who actually likes to make sure that the work others did is correct, so if I were you, I would check the clients myself.

by w2ktechman

I have seen these scenarios before, first whoever is receiving the conflicts (find both machines) and make sure that they are both configured alright. Sometimes techs will (burrow) a dhcp address and make it static for testing, then forget to change it. Or, make sure that the addresses are in the proper scope. It may be a rogue dhcp server on your network. Often rogue servers are from students studying for MCSE or Linux users.

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