•WUA (Windows Update Agent) is Microsoft’s patch engine, the same background utility used when patching a home computer using Control Panel > Windows Updates.
•Kaseya leverages WUA by invoking WUA.api, Microsoft’s exposed portions of the WUA utility
•WUA is used for all patch scans and some or all patch installations (depending on File Source Configuration)
•Scan: WUA negotiates with Microsoft to determine the patches that are missing from and applicable to the endpoint
•Install: WUA negotiates all patch installations when the File Source is configured as “Download from Internet” OR when a patch is flagged as “Internet Based Install Only”
This NOT the same as the Windows Update service, which must remain enabled and started (via Control Panel > Services):