Norman they're dedicated servers so they run a variety of operating systems , windows , linux however sometimes you need to pay extra though to run windows because of the licenses....
They're have been reports that team viewer has been hacked so if anyone has it installed i would un-install ASAP.
And scan computer with anti-virus software
https://www.reddit.com/r/technology/comments/4m7ay6/teamviewer_has_been_hacked_they_are_denying/