NIC stopped receiving packets

Hi we have our external DNS server running as a Hyper-V guest.  wierd today we were unable to access any of our sites, checked and noticed that our DNS is transmitting but not receiving packets. it has a dedicated NIC since its in our DMZ,  so far have taken following actions.:
1.  No errors reported in event viewer.
2. rebooted the server.
3. disabled and enabled the NIC.
4. uninstall and reinstall the virtual NIC from device manager.
5. disabled and enabled the NIC on the Host server.
6. Able to ping 127.0.0.1 successfully
7. Able to ping itself.
8. unable to ping the gateway .1

if anyone can assist asap. that would be great one of your productions site is down.
Thanks
R007jAsked:
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Svet PaperovConnect With a Mentor IT ManagerCommented:
You other servers in DMZ and they are working well, right? And they are on the same IP subnet as the DNS server?

In the DNS server, is the network card enabled?

If all responses are “yes” and nothing is been changed, I would say that you have a hardware failure somewhere: either the NIC on the Hyper-V host or the switch port.
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Svet PaperovIT ManagerCommented:
Could you provide us with more information, please:

Are there any changes in the network design, external firewall, switch posts, etc.?
Have you layer 2 connectivity between the NIC and the switch?
Can the server ping its default gateway? And outside host?
Which OS is used by the DNS server? Windows, Linux, or Unix?
Any other useful info…
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R007jAuthor Commented:
Hi, thanks for the prompt response.
THe DNS is windows 2003, the server cannot ping its default gateway or outside host. can only ping itself successfully.  there have been no recent changes on the network design or harware replacements.
 The DNS server is a Hyper-V guest running windows 2003.
 it has a dedicated NIC and static Ip address, dedicated switch for DMZ servers, Dell Power Connect 2048.
 i am unable to ping anything from the guest DNS server except for itself.
 I am able to ping everything from the HOST server including pinging other DMZ servers.
I am able to ping the Host server for allt he other servers in the LAN except the DMZ servers.
i have checked the cables and the switch.
hope this helps.  please let me know if you have any other questions.

Thanks
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Svet PaperovIT ManagerCommented:
Do you have another virtual machine that shares the same NIC? If yes, can you try to ping that server from it? If not, will be possible to place another VM in the same subnet connected through the same hardware NIC?

The type of the virtual NIC should be external, is that correct?
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R007jAuthor Commented:
Currently that VM has a dedicated NIC due to it being a part of our DMZ domain.  Unfortunately we cannot add another VM that can share the same NIC as the host is a production host and the host is running at max capacity.  Yes the Dedicated NIC is external.

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R007jAuthor Commented:
Yes the other DMZ servers are working fine they are part of the same switch and subnet, but they are not part of the same host server. The Network card is enabled and shows connected and under status shows packets being transmitted but nothing received.  i will be visiting our datacenter this evening to swap the switch port.  I will update later this evening.  Thanks if you can think of something else please let me know..
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jbvernejCommented:
There is a known issue with HyperV and Network with firewall and/or heavy load:
kb974909 The network connection of a running Hyper-V virtual machine is lost under heavy outgoing network traffic on a Windows Server 2008 R2-based computer
http://support.microsoft.com/kb/974909/en-us

There is a patch to apply on the HyperV layer.


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R007jAuthor Commented:
Hi Spaperov, it was the switch port moved to another port and it worked.  Thanks
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R007jAuthor Commented:
Thanks jbvernej for the tip we will be deploying more HV server in our environment i i have bookmarked the link.  in my case it was more on hardware level.

Thanks
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jbvernejCommented:

I forget to add on my previous post:

kb974909 is for W2008 R2 HyperV  without SP1

if you already have the Sp1 on your W2008 R2 hyperV host, the same issue can be resolved by the following:
2263829 - The network connection of a running Hyper-V virtual machine may be lost under heavy outgoing network traffic on a computer that is running Windows Server 2008 R2 SP1
http://support.microsoft.com/kb/2263829/en-us
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R007jAuthor Commented:
Thanks yes we have Sp1.
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