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I'm running 4 of Win2k3 64bit servers in the same subnet. It's been more than an year that I've running them without a problem.

Recently, I kept losing the connection to one of the server. Let's say it's 'server A' which has a problem. Losing the connection means that I can't access to server A from the other servers. I've checked if server A has any internet connection problems or are there any abnomal event logs in the eventvwr - but haven't found any problems.

The problem usually resolved if I restart the server again. But as time goes by, it keeps happen again and again. I can't afford to restart the server every time, and I really want to find out the reason.

Can anyone help me out? Let me know if you guys need any of more information.

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Single NIC on Server A? – Kara Marfia Jun 1 '09 at 13:18
Every server has double NIC. For public, and private. – Sam Jun 1 '09 at 13:44
up vote 1 down vote accepted

If you've got a managed switch, look at the switch logs, port statistics and port link state to identify/confirm the symptoms during the failure.

Faults with autonegotiation, bad cabling, mismatched speed/duplex and framing errors are easy to pick up with this info.

"show log" and "show interface <interfacename>" will do the trick on Cisco gear, I presume managed switches from other vendors will have similar commands.

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I'll look forward it. Thank you for advise. – Sam Jun 1 '09 at 13:43

I agree with both Marko and Nick, I've had Servers that were "going bad" to be just the switch. As soon as I tested a new switch it was working all fine. In my opinion either the NIC card is going or the switch is going.

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I'll check them for sure. Thank you. – Sam Jun 1 '09 at 13:12
I've had the same experience as Hondalex. Sometimes it's the switch, sometimes it is a NIC. Sometimes I've tracked back to find that a driver update screwed things. – NotMe Apr 10 '10 at 16:27

You could have a name resolution problem or a duplicate name/ip address.

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I've been checked them already but haven't found any duplicate name/IP in the subnet.. Thanks anyways. – Sam Jun 1 '09 at 13:10

Ensure no viruses/rookits are on the server 1st off. After that, see if the NIC is dying. You can run a continuous ping on the server outbound, script it to dump to a text file (ping -t TargetIP >> C:\ping.txt), and let it run for a bit. See if the ping traffic dies suddenly then comes back. Could be indicative of a bad NIC.

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Thank you for kind answer. I'll try it. – Sam Jun 1 '09 at 13:12

Even though the problem seesm to resolve itself with a restart, don't rule out the possibility of an issue with your switch - maybe try a different port?

Edit: Sorry - duplicate of Nick's post

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Thank you anyways! – Sam Jun 1 '09 at 13:12

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