What's the foolproof way to tell which version(s) of .NET are installed on a production Windows Server?

This question is not so much programming related as it is deployment related.

I find myself conversing a lot with the group in my company whose job it is to maintain our production Windows servers and deploy our code on them. For legal and compliance reasons, I do not have direct visibility or any control over the servers so the only way I can tell which version(s) of .NET are installed on any of them is through directions I give to that group.

So far, all of the methods I can think of to tell which version(s) are installed (check for Administrative Tools matching 1.1 or 2.0, check for the entries in the "Add/Remove Programs" list, check for the existence of the directories under c:\Windows\Microsoft.NET) are flawed (I've seen at least one machine with 2.0 but no 2.0 entries under Administrative Tools - and that method tells you nothing about 3.0+, the "Add/Remove Programs" list can get out of sync with reality, and the existence of the directories doesn't necessarily mean anything).

Given that I generally need to know these things are in place in advance (discovering that "oops, this one doesn't have all the versions and service packs you need" doesn't really work well with short maintenance windows) and I have to do the checking "by proxy" since I can't get on the servers directly, what's the foolproof way to tell which version(s) of .NET are installed on a production Windows Server? Preferably some intrinsic way to do so using what the framework installs since it will be quicker and not need some sort of utility to be loaded and also a method which will definitely fail if the frameworks are not properly installed but still have files in place (i.e., there's a directory and gacutil.exe is inded there but that version of the framework is not really "installed")

EDIT: In the absence of a good foolproof intrinsic way to do this built into the Framework(s), does anyone know of a good, lightweight, no-install-required program that can find this out? I can imagine someone could easily write one but if one already exists, that would be even better.

Solution 1:

You should open up IE on the server for which you are looking for this info, and go to this site: http://www.hanselman.com/smallestdotnet/

That's all it takes.

The site has a script that looks your browser's "UserAgent" and figures out what version (if any) of the .NET Framework you have (or don't have) installed, and displays it automatically (then calculates the total size if you chose to download the .NET Framework).

Solution 2:

You can programmatically check the registry and a few other things as per this blog entry.

The registry key to look at is

[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\NET Framework Setup\NDP\...]

Solution 3:

Found answer from here:

Check which .NET Framework version is installed

Open Command Prompt and copy paste one of the below command lines

dir %WINDIR%\Microsoft.Net\Framework\v*

or

dir %WINDIR%\Microsoft.Net\Framework\v* /O:-N /B