How to find out which version of IIS is installed

Last week I confiscated an unused dust-gathering desktop in order to install a small, development MySQL database on it. Skip forward a few days, when I received a request to set up a small website on that same box, using the already installed IIS. No problem so far.

But after browsing through the website and testing its features a bit, a colleague asked me which version of IIS I had been using. To be honest, I didn't have a clue: yes, I had set up the box, but I'm only familiar with IIS on a need-to-know-basis, and I had to look up the version myself - which turned out to be quite a task.

Normally, you'd expect any piece of software to have a "help" menu item, containing a little "about" box on which you can find most (if not too much) info about that particular version of software. This IIS version, however, didn't, or at least none of us could find it. So how do I get the version? Turns out, there are a lot of lovely ways to find out which version you are running, and here they are!

First of all, IIS versions are apparently tied to the operating system, i.e. you cannot upgrade an IIS install on a particular version of Microsoft Windows. For most purposes this sucks, but here it is a benefit. It means that you can just have a look at Microsoft's IIS page, or this Wikipedia article on IIS versions. Please note thet Wikipedia lists more entries than Microsoft, which is pretty damn funny if you think about it.

A second option is to have a look at %SYSTEMROOT%\system32\inetsrv\inetinfo.exe. Right-click and get properties, then click the Version tab. There's all you need to know.

The third possible option is to create a simple .asp page with the following code: upload it to the web server, call the page and voila! There's your version info.

Option four: the registry. It just wouldn't be Windows without a registry option now, would it? Anyway, have a look at the registry value in HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\InetStp\VersionString, it'll tell you the correct version.

Naturally I saved the best for last - here's my absolute favourite way of finding out which IIS version you're running on a particular server - server access not required, by the way. You simply look at the HTTP response header.

1. telnet mywebserver 80
2. type in HEAD / HTTP/1.0 [enter][enter]
3. Look at the line that starts with Server:

If you know of any more ways to find out which version of IIS you're running, please let me know - I'll be interested to know, and I'll post them here for sure!