title: Connection to non existing mongodb server does not throw exception
body: <p>I'm playing around a bit with the MongoDB driver for Java. So I just created a simple application to connect to a MongoDB server and select a database.<br>
  So I created an instance of <code>MongoClient</code> and selected a 'DB':</p>
  
  <pre><code>try
  {
      MongoClient client = new MongoClient("localhost", 27017);
      DB database = client.getDB("example");
  }catch(Exception e){
      e.printStackTrace();
  }
  </code></pre>
  
  <p>Because of the fact that there is no running instance of <code>mongod</code> on my machine, I expected that <code>client</code> would throw an <code>Exception</code>. Unfortunately that isn't the case.<br>
  Even when selecting the database nothing happens. It just behaves like if there was a running <code>mongod</code> instance.<br></p>
  
  <p>I looked into the documentation about the Java driver but couldn't find anything about it. Same with Google.<br>
  Is there anything I missed?</p>
  
  <p>I'm using the latest MongoDB driver (version 2.12.2) from the official website.</p>