title: socket.io : Queries around broadcasting and max connections
body: <p>I am new to Socket IO development. I wanted to know the following around it : </p>
  
  <ol>
  <li><p>MAX limit for the number of concurrent OPEN Sockets supported ? </p></li>
  <li><p>Guidelines / extra care to be taken to fine-tune the Node Server for Production.</p></li>
  <li><p>Does socket.io ensure message deliver ? or it is send-and-forget ? Also are there any node-modules which when installed leverage this feature ?</p></li>
  <li><p>In case socket.io does not support message delivery; how can I ensure that the message was sent and received successfully to the intended person ?</p></li>
  </ol>