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DHCP and Alternate Configuration (IP)

By beachj ·
I cannot figure this one out and was wondering if someone has any ideas. I have a DHCP server running and assigning addresses to PC's on the network. I have also configured the Alternate Configuration, within the OS on each machine, to have a different IP address (like a backup address and different subnet). Usually when the machines get turned on they fail to grab an address from the DHCP server and default to the Alternate IP address, which is not even on the same subnet as my network. Is there any way that I can increase the timeout on the DHCP request so that the server has time to grant an address before the workstation decides to use the Alternate? Any one? Please?
Thanks,
Jeff.

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by sgt_shultz In reply to DHCP and Alternate Config ...

wow, i have never had this problem and i'd be looking at a possible physical network layer problem. good cables everywhere and everybody locked up or down to a media type (using autosense can be problematic) and update all the nic drivers for good measure.
i've never messed with the alternate ip thing so can't answer your question.
i'd just run static addresses...and use dhcp just to help me with initial install of ip devices and to get guests up and running...but yes you need to fix what ever is doing this.
do you have any other possible symptoms of poor network performance?
because i am not even gonna suggest ipconfig /renew in a batch file. just too ugly...

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by BFilmFan In reply to DHCP and Alternate Config ...

The defualt time out period is 4 seconds.

Configurable TCP/IP registry information is available here:

http://support.microsoft.com/default.aspx?scid=kb;en-us;314053

Unless your DHCP server is overloaded, you have have some other network traffic issue.

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by beachj In reply to DHCP and Alternate Config ...

The DHCP server is extremly old but there is no chance of it being replaced anytime soon. There were two different scopes, with only one active, up until yesterday. I copied the information and removed the extra scope to see if that works. Unfortunately I cannot "fix" the physical wiring, if that it the problem, because the landlord would need to do that. How could I test the physical wiring though? Any programs that can be run that will test that, and possibly other things?
Cheers,
Jeff.

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by CG IT In reply to DHCP and Alternate Config ...

first off whatx the reason for a second scope? you can have a superscope in DHCP but unless you've got a lot of hosts, a superscope is just a lot of admin work.

Comps running W2K/XP have the ability to assign themselves an IP address if there is no DHCP server available to provide them one. If your DHCP server is not providing clients with an IP address fast enough then I would not assume it's a DHCP problem rather a network utilization/congestion problem.

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by CG IT In reply to

you do mention that some comps get an IP address so activation of the scope and authorization of the scope doesn't appear to be the problem. What other troubleshooting have you done?

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by CG IT In reply to

ok so how many clients are there? It's possible that if you have a ton of clients booting up in the morning all wanting an IP address at the same time, network traffic gets so congested that ooops, some gets dropped off because the discover/acknowledge/accpet unicasts get bogged down. But thats a rare case and usually happens on very old networks runing NT that use hubs and base10T with very large amounts of clients running W9X.

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by CG IT In reply to

I dunno, I would do some monitoring on the network to find out whats happening to the DHCP packets on Discover/Acknowledge/Accept blah blah unicast.

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by CG IT In reply to

another subnet just in case they want to go back to the old network? Geez. whatever is on the old network they want I would put on the new network. Who needs the hassle.

do some packet captures for DHCP traffic on client comps see where the packets go, what happens to them when DHCP appears to take a header into the abyss. The gotta go somewhere [exluding the well know great blackhole packet void].

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by beachj In reply to DHCP and Alternate Config ...

Hey thanks for all the help!!!

The second scope is a backup just in case the office wants to go back to using the old network (kind of like a fail safe requested by the users there). Sometimes it happens that a PC will aquire an IP from the DHCP server and the one right next to it will get the Alternate IP. ipconfig /release & /renew picks up the IP from the DHCP server and all is well. Just upon boot and not all the time, less than 40% of the time, the PC fails to contact the DHCP server... I have tried ping, pathping, tracert... everything but sit there and watch the packets flow (maybe I should do this though...). Looked on the DHCP server for events but nothing is showing up that would signify there was a comms issue... Pretty confusing to me.

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