Windows 7 Units with IP Conflicts on Domain (WinXP Units Working Normally)
This issue hit just last week around Thursday Afternoon; no changes were made to the units. I have been attempting to fix/research this issue for the past 2 working days and have not found a solution to the problem. I have 2 Windows 7 Units (x64); one is a Lenovo T520 and the other is a HP Laptop - I believe both use Intel Drivers for their wired network. I only mention them because they are completely different make/model laptops having the same issue. The only thing in common is Windows 7 x64 General Information: When attached to a stand alone 'Linksys E1500 Router' both devices are able to get 192.1 address from the router. Then when attached back to our Domain Network they return to the 'IP Conflict' issues and are never able to get IP Addresses. Both units cannot get an IP Address from the Domain Wireless Network either. I took one unit off the Domain and is still unable to get an IP Address. I am currently on a WinXp Laptop (Lenovo T61) connected via the same exact network wire and Domain and I am able to connect without issue. Both units were working normally (Win7 x64 units that aren't working now) until they had to renew their lease from DHCP. Now, all I see are tcpip errors in the Event Log while the adapters attempt to get an IP Address from the DHCP server. It states that IP Address x.x.x.x is already assigned to -MAC ADDRESS- and it just scrolls different IP after IP with the same MAC Address over and over. So I can see that the DHCP server assigns an IP to the Win7 units but immediatly causes an IP Conflict and they get disconnected. Then it just keeps looping and causes a ton of BAD Addresses on the DHCP server. The MAC Address that it lists for the Conflict is a bad address. What has not worked: Rebooting into Safe Mode+Net - Reinstalling various Intel Network Drivers - Rolling Back Drivers - System Restore - Various DoS Commands via netsh / nbtstat / ipconfig - Router Firmware Upgrade - Turning off IPv6 Any thoughts or ideas would be appreciated. I've searched through TN and attempted a few 'like' fixes but obviously has not resulted in a solution yet.
August 29th, 2011 11:20am

Is a reservation added for the IP address of these two machines? It seems like an IP address that was already (statically/dynamically) assigned to some other machine had been added as a reservation for these two machines. As a result, the DHCP hands them these IP addresses even though they have already been assigned. Hence the conflict. Please revert back with the status here, thanks! Kunal D Mehta - a Windows Server Enthusiast | My first TechNet Wiki Article
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August 30th, 2011 4:34pm

I've been browsing around a few different places for an issue I'm working on similar to this and I've seen a few different options which include the possibility of a misconfigured device (like a copier or network printer) that's connected to the Domain/DHCP server/network with an manually configured IP address of 0.0.0.0 which messes up the DHCP being able to assign the device an IP for Windows 7 and windows Vista machines. The only other reasonable fix I found suggested this which I think you may have done.. You can test if the issue is due to GPOs using the following process: 1. Unjoin the computer from the domain 2. Delete the computer account form Active Directory 3. Create a new OU for the computer account in Active directory and block GPO inheritance so no GPO was applied to computers in this OU 4. Create computer account for the computer in the new OU before joining the computer in the domain 5. Delete any computer local policy by going to \Windows\System32\GroupPolicy and deleting everything in this directory. 6. Join the computer to domain I'm going to try that and a couple other things once I have an opportunity, but if it fixes your issue let me know. Also in ipconfig /all when you run it does it show a Default gateway at all or is it blanked out?
September 14th, 2011 3:01am

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