How many hosts is Microsoft phoning everything home to? Is it feasible to just block them all with an external firewall so a Windows box simply can’t reach Microsoft? The article below says that Windows 10 is ignoring the hosts file and phoning home anyway, so it seems like an external firewall would be the way to go. Of course, as soon as you get your Microsoft blacklist established, if you’re still pulling OS updates, Microsoft could just change the hosts that the telemetry apps are using, and you’re back to square one. You would have to use a packet sniffer, firewall log, etc and make a new catalog of hosts that Microsoft is using.