title: Host of an NSURL without the subdomains
body: <p>How can you <strong>get the host of an NSURL without the subdomains</strong>?</p>
  
  <p>Here are some inputs.<br>
  The part that should remain is in bold, and what should be stripped is in italic:</p>
  
  <blockquote>
    <p><strong>server.com</strong><br>
    <i>www.</i><strong>server.com</strong><br>
    <i>media.</i><strong>server.com</strong><br>
    <i>host1.media.</i><strong>server.com</strong>  </p>
  </blockquote>
  
  <p>So far, sounds very easy to implement.<br>
  But it should also correctly handle the following inputs, as well as any weird case I didn't think about that is commonly accepted or specified in any relevant RFC.</p>
  
  <blockquote>
    <p><strong>server.co.uk</strong><br>
    <i>media.</i><strong>server.co.uk</strong><br>
    <strong>127.0.0.1</strong><br>
    ...</p>
  </blockquote>