>>>>In Windows 8 (maybe in Win7 too) if I block outbound connections from the OS then within a few seconds/minutes my internet connection stops working. I have tested this at least 10 times and get the same consistent result. I must allow the outbound connections from the OS (and there are about 3 or 4 different ones on start-up) or I lose internet access... Then I have to reboot and start again.
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>>>Did you try to block OS outgoing traffic to certain addresses only? After checking who is?
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>>So after a few hours trial and error to confirm my gut-feel / impression I found the following. It is not a definitive study because I don't have time for that but on booting Win8 it attempts to make calls to various IP addresses. The 2 sets of calls that are made every time you reboot (there are others I have seen but they don’t happen every time you boot) are:
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>>1) 157.55.44.* - 157.55.122.8 - These use https, port 443 and resolve to wns.windows.com. It appears I can continue blocking these for quite some time without effect on my connectivity.
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>>2) 213.199.148.* - 213.199.149.* - These use http (at least initially), port 80 and resolve to lon9.msecn.net which apparently is Microsoft Edge Content Network. The call is made by svchost.exe. If I leave the firewall warning on the screen without answering Allow or Deny (which I assume keeps it in a sort of suspended state) then I can continue to access the internet as normal. But if I block this then within minutes my internet access to most websites is affected including to google.com, wikipedia.com, even Hotmail.com. Not all sites are affected, most but not all, and I cannot find a pattern between the few I can still get to. I have no idea what MS Edge Content Network is or does or why it should affect my internet connection like this. But if I want access to most sites I need to allow this.
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>Hrm... If I google "Microsoft Edge" I see references to MS Exchange.

I don't use Exchange. When I Googled for lon9.msecn.net I found discussions about Microsoft Edge Content Network but I didn't go into what its all about. I just see that if you block this then websites fail to load. No idea what it does.