You confirm the problem in your response:
"usually"
"only two"
That means that Google.com is still needed as the front-end to MS documentation. Ergo, it doesn't matter how many domains they use to host their documentation.
Re:Introducing docs.microsoft.com
by mistermann on Wednesday May 04, 2016 @12:44PM
(#11629597)
Not to mention search on MS sites essentially doesn't work (unless something has changed).
[0] https://msdn.microsoft.com/library [1] https://technet.microsoft.com/library/default.aspx