A. There are a number of different ways to detect which .NET Framework version is installed on a computer. Probably the easiest way is to check the .NET Framework installation registry subkeys.

Open the HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\NET Framework Setup\NDP registry subkey. You'll see a child key, which represents the .NET Framework version that's installed on the computer. You might have multiple key entries, which shows multiple .NET Framework versions installed, as my following query-and-output example shows (I have versions 2.3 and 3.5 installed).