While system specific updates will still reach out to WSUS or SCCM, or against Microsoft Update if the machine is configured to use Microsoft Update instead of Windows Update, the Store App updates are not yet cached or supported on WSUS or SCCM yet.
So actually, the machine is going out to url- only to update the Windows Store Apps.
Of late, several customers have reached out to my team asking why their Windows 10 15 clients, which are managed by WSUS or SCCM are going online to Microsoft update to download updates.
One of the main reasons why you may be experiencing a significant bandwidth consumption is because of the Proxy configuration.
While both these scenarios are interconnected, if you are observing Scenario A then you may also report Scenario B.
Delivery optimization (DO) was introduced in TH2, but it was only used for downloads of large content.
DO in 1511 build is used in about 50% of the downloads, and when DO isn’t used the download switches to BITS.
From 1607 build onwards, it is the default downloader for Windows Update and Windows Store content.