Let's see which name servers Microsoft is using right now:

microsoft.com.          1d20h7m8s IN NS  DNS4.CP.MSFT.NET.
microsoft.com.          1d20h7m8s IN NS  DNS5.CP.MSFT.NET.
microsoft.com.          1d20h7m8s IN NS  DNS7.CP.MSFT.NET.
microsoft.com.          1d20h7m8s IN NS  DNS6.CP.MSFT.NET.
microsoft.com.          1d20h7m8s IN NS  z1.msft.akadns.COM.
microsoft.com.          1d20h7m8s IN NS  z2.msft.akadns.COM.
microsoft.com.          1d20h7m8s IN NS  z6.msft.akadns.COM.
microsoft.com.          1d20h7m8s IN NS  z7.msft.akadns.COM.

Let's do a queso on the last four.

$ sudo queso z1.msft.akadns.COM:53
216.32.118.104:53       * Linux 2.1.xx/2.2.xx 
$ sudo queso z2.msft.akadns.COM:53
32.96.80.17:53  * Linux 2.1.xx/2.2.xx 
$ sudo queso z6.msft.akadns.COM:53
207.229.152.20:53       * Linux 2.1.xx/2.2.xx 
$ sudo queso z7.msft.akadns.COM:53
213.161.66.158:53       * Linux 2.1.xx/2.2.xx 

It's Linux, all right. 

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