​I recently came across an installation issue where the prerequisites would fail on the ASP.NET 4.0 Registration Check.

TechNet has always suggested the following:

http://technet.microsoft.com/en-us/library/jj656649.aspx

 

"ImportantImportant
You must install IIS before installing .NET Framework 4. If you installed IIS after installing .NET Framework 4, you must register ASP.NET 4.0 with IIS. Open a Command prompt window by using the Run As Administrator option, and then run the following command:

 

%WINDIR%\Microsoft.NET\Framework64\v4.0.30319\aspnet_regiis.exe -r

"

I installed IIS prior to installing .NET Framework 4, but noticed that there was a failure on ‘The ISAPI and CGI Restrictions are disabled or missing’ check after I had already Allowed the ISAPI and CGI Restrictions in IIS.

The following Error was seen:

netextisapi1.jpg

Screenshot of ISAPI and CGI Restrictions in IIS appear to be set correctly:

netextisapi.jpg

I performed an IISRESET successfully

Open a Command prompt ‘as Administrator’ using the preferred command resulted in prerequisite check Succeeding:

netextisapi2.jpg