how does iis recognize that request is for mvc or webforms?

Question

When Application pool receive the request, it simply pass the request to worker process (w3wp.exe) . The worker process "w3wp.exe" looks up the URL of the request in order to load the correct ISAPI extension. ISAPI extensions are the IIS way to handle requests for different resources. Once ASP.NET is installed, it installs its own ISAPI extension (aspnet_isapi.dll) and adds the mapping into IIS.   

ok thats true so my question is how does it recognize that which extensions to be loaded
for that request?? MVC / WebForms?

When and were the IIS come to know that request is for MVC or WebForms Application?

How framework decide which Modules should handle the request and decide to render page content or views in MVC.

Thanks in advance......