Windows Update Delivery Optimization: FAQ
Windows Update Delivery Optimization lets you get Windows updates and Windows Store apps from sources in addition to Microsoft. This can help you get updates and apps more quickly if you have a limited or unreliable Internet connection. And if you own more than one PC, it can reduce the amount of Internet bandwidth needed to keep all of your PCs up-to-date. Delivery Optimization also sends updates and apps from your PC to other PCs on your local network or PCs on the Internet.
Delivery Optimization is turned on by default in Windows 10.
How is my PC used to send apps and updates to other PCs?
Delivery Optimization downloads the same updates and apps that you get through Windows Update and the Windows Store. Delivery Optimization creates a local cache, and stores files that it has downloaded in that cache for a short period of time. Depending on your settings, Windows then send parts of those files to other PCs on your local network or PCs on the Internet that are downloading the same files.