DHCP and Client Static IP

[JiggaWatt]

Hello!

I have an issue with a client machine that has a static IP. For some reason despite having an IP assigned to this PC, it is broadcasting out for an IP to the DHCP server.

To give you the rundown of the machines involved:
Client - WindowsXP SP3

> is asking for an IP from < (Bad. I don't want this.)

Server - 2008 R2 with DHCP, AD, and DNS on the same machine

I am under the impression that if a client is assigned an IP via the LAN Connection Settings in Windows, then it has no reason to broadcast out, "Gimme an IP!"

The client houses some software that other hosts connect to. I will know when it is 'flocked' when a user calls me up and says they can't log in. I will look in the DHCP list and voila! There is the machine name with an IP assigned that shouldn't be in the list in the first place. Once I delete the entry from the lease list, about 15 min later connectivity is resolved, since there is only one machine out there the hosts need to talk to versus two.

I ran Wireshark and traced down that the MAC address for the static IP (the one preferred to be used) and the dynamic IP ( the one dished out somehow by the DHCP server) are the same.

The only thing I can think of is somehow this client machine might have been replaced, recovered, sandblasted, etc. while physically plugged into the network. It broadcasted for an IP and got it. In the mean time the IP was configured manually and then applied but now the entry is in DHCP still and somehow asks for the credentials and gets it despite being static.

?

[Midknyte]

Just making sure, but is the static IP outside the DHCP scope?

If you want to filter out the static client's MAC from DHCP, this article might help:
http://www.petri.co.il/filter-mac-ad...allout-dll.htm

[JiggaWatt]

Yes, the static IP is outside the dynamic scope.

That MAC address filtering looks like a good tool. I guess I needed the proper nomenclature for what I am attempting to do. I will give it a try and see what happens. I will post back either way.

Much appreciated, Midknyte.

[JiggaWatt]

The solution was right under my nose.

The filtering is built right into 2008 R2. Sad thing about it, I actually remember passing over it a couple times prior to posting here but didn't pull the trigger for fear of disrupting something. I added the MAC to a Deny filter in the IPv4 node of DHCP and BAM! You may want DHCP, but you ain't gettin' it!

Thanks again, Midknyte.

[Midknyte]

Cool. I'm glad we got you pointed in the right direction.