title: Missing Group Built-in Administrators (SID: S-1-5-32-544) in HttpContext.User.Identity
body: <p>I am using windows authentication and want to know if an logged in user belongs to the group 'Built-in Administrators'. I am using the following code snipped to find that out in my MVC4-Application:</p>
  
  <pre><code>   // user identity
      var lIdentity = HttpContext.User.Identity as WindowsIdentity;
  
      // get all Group-Sids, the current users belongs to.
      var lSids = lIdentity.Groups;
  </code></pre>
  
  <p>The group Built-in Administrators (SID S-1-5-32-544) is not listed in <code>lSids</code>.</p>
  
  <p>But when I use the cmd <code>whoami /groups</code> on the same user, it shows the SID S-1-5-32-544.</p>
  
  <p>How can I find out in my MVC4, if an logged-in user belongs to the Build-In Administrators group.</p>