by boco » 26.06.2016, 19:58
1. This is support of WSUSOU (WSUS Offline Update) that has nothing to do with Microsoft's WSUS.
2. WSUSOU will download and keep a local repository of all security-critical updates (minus obsolete and superseded ones) for a selected OS.
3. The created media (or ./client directory) determines missing updates on the target system and will install only those. However, for determination, the Windows Update Client is used. It is thus subject to the same delays the WU itself is to.
Microsoft update catalog: http://catalog.update.microsoft.com/v7/site/
Windows Install media download: https://support.microsoft.com/en-us/help/15088/windows-create-installation-media