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Last week we moved our servers to another room for security reasons, they have the same port configuration and it has seemed like nothing has changed. The servers seem to be up and working fine, not reporting any errors and are all accessible and doing what they're supposed to be doing (for the most part).

Here is where the issue arises. About 20% of the computers (Windows 7) in our offices are not getting the correct network settings (IP, gateway, DNS, etc). I would do an IPconfig /flushdns, IPconfig /release, IPconfig renew and still, nothing would change.

All it would say is "local connection, no internet access". So far the only thing I can find that fixes it, is an occasional reboot of the users computer, or unplugging the Ethernet cord from the back of the machine and then re-plugging it in.

That fix is also only temporary, the problem would occur again at some point during the week. All the servers have static IP addresses and are on Server standard 2008 SP2.

Just for clarification again, the issue is happening on the users' machines, and not all of them. If I set a static IP address to the machines, the computers work fine and I don't need do any unplugging or rebooting. We do not want to set static IPs on all the machines, so that is not a "fix" for us.

I can't determine if this is a DHCP or DNS issue.

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migrated from superuser.com Nov 10 '11 at 16:20

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Have you considered temporarily rolling the rack back to where it was and see how it works? Bad jack in the new room perhaps? –  techie007 Nov 10 '11 at 16:54
    
We had the jacks tested, and the jacks are 100% working properly. That was an initial thought of mine as well. A friend of mine said I should reset the winsock on the servers, do you think that would work. –  Mike K Nov 10 '11 at 17:02
    
Nope, but hey, it's your sever to try. :) If it's as you said, and you just moved it and it's still plugged into the same switch (port), then the software stack shouldn't care at all. How did you test the jacks? Were they just connection tested, or were other tests performed as well? –  techie007 Nov 10 '11 at 17:22
    
The organization I work for is affiliated with a University, so we use their internet and make it our own. The University owns the port, so they came in with all their tools and gear and ran all sorts of tests. What exact tests were performed? I cannot tell you, they keep things a little close to the chest. But they did assure me that nothing was wrong with the ports. We are also using the exact same ethernet cords, you dont think the cords could be dying do you? –  Mike K Nov 10 '11 at 17:26
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I just wanted to let Techie and everyone else know, I figured out what the issue was. The issue was coming from a home wireless router we had set up here. Once that was unplugged it stopped pulling subnets from that router. Silly thing! –  Mike K Nov 10 '11 at 20:34

2 Answers 2

I cant determine if this is a DHCP or DNS issue.

It looks like a DHCP issue.

I'd use ping to check packet loss from the troublesome desktop computers to the DHCP server. I'd check/swap cabling of the DHCP server.

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So possible bad network cable going into the DHCP server? –  Mike K Nov 10 '11 at 16:07

While you run ipconfig /renew on the client, Use Microsoft Network Monitor or Wireshark to monitor DHCP traffic and verify that you're actually seeing a response from the server.

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