title: 3 classes in Java which implement system independent datagram communication?
body: <p>I'm revising for a network exam and this is one of the questions in a few past papers.</p>
  
  <p><strong>Name 3 classes in Java which implement system independent datagram communication?</strong></p>
  
  <p>I was led to believe there were only 2 class to implement system independent datagram communication;</p>
  
  <ul>
  <li>DatagramPacket </li>
  <li>DatagramSocket</li>
  </ul>
  
  <p>What could the 3rd class be?</p>
  
  <p>Answers greatly appreciated</p>