How can I tell if I have Windows 2012 R2 or just "2012"? I can't seem to see any signs of "R2" anywhere yet I ordered a (remote) server with this installed and I want to verify I have the correct edition installed before I go any further with the server build.
Drop into a command prompt and issue either of the following commands;
systeminfo | findstr OS
You can then use this table to determine the version;
Operating system Version number Windows 8.1 6.3* Windows Server 2012 R2 6.3* Windows 8 6.2 Windows Server 2012 6.2 Windows 7 6.1 Windows Server 2008 R2 6.1 Windows Server 2008 6.0 Windows Vista 6.0 Windows Server 2003 R2 5.2 Windows Server 2003 5.2 Windows XP 64-Bit Edition 5.2 Windows XP 5.1 Windows 2000 5.0
Based on your comment, it would appear you're running Windows Server 2012 as opposed to Windows Server 2012 R2
If you have the GUI installed an instant visual clue will be the absence (Server 2012) or presence (Server 2012 R2) of an actual Start button on the taskbar.
In GUI it's easy to check the version: Control Panel > System and Security > System
You could also search for the Software Identification Tag File (ISO 19772). This is an XML file on your drive. Just search for: regid.1991-06.com.microsoft.*.swidtag
Usually for Windows OS the files are located in "c:\ProgramData\regid.1991-06.com.microsoft". In this file you will find the tag <product_title> e.g.
<product_title>Windows Server 2012 R2 Datacenter</product_title>