title: ASP.NET MVC 4 and ExtensionlessUrlHandler
body: <p>I use VS 2012 and created two application:</p>
  
  <ol>
  <li><p>Application#1. <strong>MVC 3</strong>, NET 4.5</p></li>
  <li><p>Application#2. <strong>MVC 4</strong>, NET 4.5</p></li>
  </ol>
  
  <p>If I compare web.config of these applications, I see the app#2 (MVC 4) has the following handlers registered:</p>
  
  <ol>
  <li>ExtensionlessUrlHandler-ISAPI-4.0_32bit</li>
  <li>ExtensionlessUrlHandler-ISAPI-4.0_64bit</li>
  <li>ExtensionlessUrlHandler-Integrated-4.0</li>
  </ol>
  
  <p>Could anybody please explain how and when they are used?</p>
  
  <p>One more question (optional). If these handlers are required now, where should I put my handlers? Before or after them?</p>