Server Operating System
Most Popular Server Operating Sustems Popular server operating systems include Windows Server, Mac OS X Server, and variants of Linux such as Red Hat Enterprise Linux (RHEL) and SUSE Linux Enterprise Server.
According to SpiceWorks, this list is the most deployed on-premises server operating systems (August 2016):
Windows Server 2003 Windows Server 2008 Windows Server 2012 Linux (excluding RHEL) Windows Server 2000 Red Hat Enterprise Linus (RHEL)