Cloud servers could have both Windows server and Linux distributions as their OS.
The OS can be selected during the ordering process. it is also possible to change the OS from Windows server to the desired distribution of Linux and vice versa, any time you want.
These are the common operating systems that come with the servers:
CentOS
Ubuntu
Debian
Windows Server
Please note that due to a lack of the required resources for Windows servers, the first two plans come only with Linux distributions.