IP Address Conflict with DHCP


New Member
I'm testing Vista RC2 on our LAN and it's doing something really strange. It's attempting to tell our DHCP server that there is a conflict on every single address in it's scope.

I can hit refresh on the Microsoft DHCP server and just watch the red X's count up the scope until I power off the Vista box or set it to a static IP address.

On the Vista desktop, it's telling me that there is an IP address conflict and that the adapter will be disabled. Meanwhile, our DHCP server no longer has any addresses in it's scope to hand out to new clients.

Needless to say, this is not good. I have to go into the DHCP server administrator and hand delete all of the conflicting IP address entries.:eek:

Has anyone else ran into this and is there something that I can change to keep this from happening?

This is not a sophisticated fix but it will work. If you install an earlier Windows version and let it communicate with the DHCP server it will successfully assign an IP address to your computer. Then when you replace it or upgrade it with Vista the same IP address will be kept.


Ray Z.

That is an interesting problem. Installing another windows version may help but its a complete waste of time really.

DHCP should only be enabled if you have a router which supports it. Go into your network settings and make sure you have it obtain and IP address automatically instead of assigning one and if you must assign one then make sure its not conflicting. Also make sure you have obtain DNS automatically. It should work.

Check your router to see if DHCP is enabled and assign a class to it, for example: or whatever. Make sure your subnet mask is correct. I mean it really shouldnt matter but it always helps to assign the right subnetmask.

Check your IE connection settings under lan settings and make sure its all set hte same. Sometimes conflicting addresses and settings will cause major problems. Just take a step back from the problem and go over all the configs, you will see something probably isnt set right. And if the IP address still says conflicting with another then ping the other address and see if it is actually in use.

DHCP Server

Everything you say is true. The reason I had a problem at one time was probably because my router was in decay and later failed but I don't really know that for sure. There may have been some other problem as well. When I replaced my router the DHCP function worked as expected. One thing I noticed with my new Netgear router was that its selection of IP addresses with the DHCP function did not stabilize for several days. As a result the various computers on the net had changing IP addresses every time they were booted. I talked to the Netgear tech support person and he had no answers.

The changing IP addresses posed a problem for inter-computer communications as each had to know the IP address of the others. I later found a feature in the Netgear administrative set called LAN IP Setup which allowed the internal IP addresses to be fixed once they had been selected by the DHCP function.

I'm glad it helped. Anymore problems just post your questions. Just some advice, invest in a good Belkin or Cisco router. I would trust them more being a network tech but thats just me. Everyone has their own preference. Also, make sure your router has security. I prefer to use Mac filtering even though im on cable. I have a few systems with 5 routers. Some systems I dont want being able to talk with one another. It helps deny and accept things alot better. The security aspect of it is great. Hell, ill give someone the pass for my router cause I know once they are in they cant talk to any machines.



I had a problem yesterday morning with a Vista machine saying there was an IP conflict and the domain kept coming up as unrecognized. I finally set it to a static and checking the DHCP log noticed several hundred entries of renewing the ip address with the machines name. As soon as I set it to static it recognized the domain and played nicely.

It almost seemed like Vista was having an IP conflict with itself.

I ran in to this problem as well when I was beta testing Vista and then when it was officially release. I called Microsoft and after 4hrs on the phone we came up with a fix. You have to edit the registry, so go to regedit.

HKey_Local_Machine\System\CurrentControlSet\Servic es\Tcpip

Highlight the Parameters folder and add a new Key.
The key has to be DWORD, name the Key ARPRetryCount, and set the value to 0.

That should get the machine connected to the domain and allow you to add all domain assets to your local security listings.


Forgot to add, sfter you edit the registry you can take it off of static and DHCP will work


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