How can I tell what version of IIS is installed?

Solution 1:

As a more general answer, not specifically aimed at your question, Microsoft has a support article which lists all old versions and the operating systems that provide each one.

IIS version   Built-in  
5.0           Windows 2000
5.1           Windows XP Pro
6.0           Windows Server 2003
7.0           Windows Vista and Windows Server 2008
7.5           Windows 7 and Windows Server 2008 R2
8.0           Windows 8 and Windows Server 2012

Current versions are on Wikipedia

8.5           Windows 8.1 and Windows Server 2012 R2
10.0 v1607    Windows Server 2016 and Windows 10.*
10.0 v1709    Windows Server 2016 v1709 and Windows 10.*
10.0 v1809    Windows Server 2019  and Windows 10.* October

Solution 2:

When you have IIS Manager open, you can click Help -> About to see the version.

Solution 3:

You can look at %SYSTEMROOT%\system32\inetsrv\inetinfo.exe. Right-click and get properties, click the Version tab.

You can also look at an 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:

Solution 4:

Windows XP has IIS 5.1 installed, so use the IIS 5.0 procedure. See this article for an overview of IIS 5.1:

A look at IIS 5.1 in XP Pro - What's different from IIS 5?

IIS 5.1 is a feature only to be found on Microsoft's XP Pro operating system. It is not installable (reliably) on XP Home. Additionally, there are no plans to update IIS 5.0 on Windows 2000 to IIS 5.1.

IIS 5.1 is basically the same engine as IIS 5.0 but since XP is a client operating system, it has the built in limits that are customary for Microsoft’s client operating systems—such as connection limits and only one Web site. Even though based on IIS 5, there are significant differences from IIS 5.0 that you should know about.

You could also open a page in the browser which runs this simple asp Script:

<% 
    response.write(Request.ServerVariables("SERVER_SOFTWARE")) 
%>

As a side note: it is interesting that IIS (beginning with Windows Server 2000/version 5.0) can't be upgraded without upgrading the operating system. Every Windows version has it's own IIS version:

Windows NT 3.51          1.0
Windows NT 4             2.0-4.0
Windows Server 2000      5.0
Windows XP Professional  5.1
Windows Server 2003      6.0
Windows Vista            7.0
Windows Server 2008      7.0
Windows Server 2008 R2   7.5
Windows 7                7.5
Windows Server 2012      8.0
Windows 8                8.0
Windows Server 2012 R2   8.5
Windows 8.1              8.5
Windows Server 2019     10.0