The WSUS server and SCCM will synchronize updates with Microsoft Update on the desired schedule.
- The top-most server in the hierarchy synchronizes with Microsoft Update. All others synch that with top level server.
- Manual synchs only add new updates. Scheduled synchs also include changed and removed data.
- The first synch should be started in late afternoon. Monitor the wsyncmgr.log file until you see an entry saying "WSUS synchronizing categories, processsed 0 of 820 items". The numbers may be different, of course. Allow the process to run overnight.
- Scheduled synchronization should run every evening, to detect any new or re-released updates.
- If multiple WSUS servers are used, update the lower level ones from the top level after it's synchronization has completed.