Hyper-V has now gone through a number of software iterations and you may need to be able to quickly determine exactly which version of the software you're running. There are quite a few methods by which this task can be accomplished. In this post, I'll provide you with two GUI-based and one command line method for accomplishing this task.
GUI method 1
The easiest way to determine your Hyper-V build number is to open the Hyper-V Manager and go to Help > About. This results in a screen like the one below.
Hyper-V Manager About window
GUI method 2
You can quickly determine the exact Hyper-V build you're running from Windows Explorer. Browse to C:\Windows\System32 and right-click the file named vmss.exe. From the shortcut menu, choose Properties. Once you're on the Properties page, choose the Details tab. In the figure below, you'll see that I'm running Hyper-V build number 6.1.7600.16385, the one that ships with Windows Server 2008 R2.
VMMS.exe properties page
Command line method
Sometimes, you need to be able to grab a file version via a command prompt. The command below will retrieve the file version for the vmms.exe file.
wmic datafile where name="c:\\windows\\system32\\vmms.exe" get version
Command line method screenshot