Windows is unable to resolve Fully Qualified Domain Names

Hello, I thought I would share this experience as it took me a bit by surprise and I ended up having to call Microsoft support. I am not stranger to P2V migrations or restoring servers from backup, but this one had me just stumped.

Basically I was in the position of having to restore a server from backup. The server was running Windows Server 2008 R2, but I believe this fix is applicable to other Windows platforms. After the restore I noticed the networking side of things just weren’t working at all. No problem, my regular routine is to simply uninstall the NIC in Device Manager, then run the good old “netsh int ip reset” command from the CLI. Reboot and things are happy, or are they..?

After the restart I was able to re-install the NIC and set a static IP, however I was NOT able to resolve anything using DNS. I could ping local addresses and I could ping public addresses by IP, but nothing I had to resolve would work. Both the PING and NSLOOKUP commands would fail. Really strange, the DNS Client service was even happily running along. Nothing helpful in the event log and no amount of re-installing different network adapters seemed to resolve it.  Also attempted flushing DNS cache and setting different static DNS servers.

After giving up and calling Microsoft, they had it fixed in about 5 minutes by following these steps. “RESET TCP/IP STACK AND WINSOCK”

 

1. From a command prompt, run the following command:
set devmgr_show_nonpresent_devices=1

2. Open device manager:
Command: devmgmt.msc

Change view setting to show “hidden devices”.  This is really for removing NICs that may no longer present.  Great for VMs.

 

 

 

 

 

Remove adapters that are no longer connected.  Indicated by a light grey text/icon.

3.  Take backup of following registry keys before deleting(Important) :-

Config Key : SYSTEM\CurrentControlSet\Control\Network

Only delete config item under network folder.

Network Interfaces under SYSTEM\CurrentControlSet\Services\Tcpip\Parameters\Interfaces

Only delete the folders under “interfaces”

4. Run following commands in cmd as admin :
• netsh int ip reset – reset TCPIP information
• netsh winsock reset – reset Winsock service

5. Reboot the Server
After reboot, enter the IP address manually on adapters to get the Machine back on the network

6. If the issue persists
Take Backup of Winsock and Winsock2 from

SYSTEM\CurrentControlSet\Services\

Delete winsock and winsock2
Import these registries from another Server of Same OS that is working fine.

Regards,
Adam Tyler

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