title: Communication between EC2 Instances
body: <p>I am running a few EC2 Instances.  How can I communicate between them?  I have tried pinging them from within the others using private and public ips, but get no response.  One of my instances is running from Availability Zone us-east-1a and another from us-east-1d.  </p>
  
  <p>I am running Windows on them.</p>
  
  <p>Do I need to do anything from Management Console?</p>