Perform the following procedure on the new WSUS destination server to verify that it is configured properly and functioning correctly before you point the WSUS clients and any downstream servers to the new WSUS server.

1. In Server Manager, click Tools, and then click Windows Server Update Services.
2. In the WSUS Administration Console, expand Computers, and verify that all the Computer Groups that existed on the source server are displayed.
3. Expand Synchronizations. In the Actions pane, click Synchronize now. After the synchronization is complete, (this may take several minutes), confirm that Succeeded is displayed in the Results column.

If the synchronization fails, click Options. Confirm that the Update Source and Proxy Server settings and password are correct. Confirm that the firewall access is configured correctly for the new server’s environment. Make the necessary changes, and then run the synchronization again.

Select a client computer so that you can force a detection to verify that the client and server communication is functioning correctly. Use the ollowing procedure to perform this verification:

1. Open a command prompt and type wuauclt.exe /detectnow to force the detection.
2. After the detection is finished, open Windows Explorer and check the %WinDir%\WindowsUpdate.log to verify that the forced detection was successful.

https://technet.microsoft.com/en-au/library/hh852343.aspx

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