petri.com/turn-off-telemetry-windows-7-8-windows-10
In April 2015, Microsoft released a non-security update for Windows 7 and 8. It added a new Windows service called the Diagnostics Tracking service, which changes the way in which the OS gathers, collects, and sends your diagnostics information from your computer to Microsoft’s servers.
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All the listed updates make changes to the operating system that results in it transmitting data through hard-coded servers, vortex-win.data.microsoft.com and
settings-win.data.microsoft.com.
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Also note that traffic to these servers is encrypted by SSL (HTTPS traffic), which makes it a bit more secure, but also very difficult to determine what exactly is being sent from your computer.
The author, Daniel Petri, doesn't go into why you'd want to turn off Telemetry, other than as noted, there's no way to tell what data is sent. He then goes through the steps necessary to turn this off.
