title: How to learn IP address of open server on same AWS security group
body: <p>I am running two EC instances.  They each run a python script and need to communicate, potentially using Python's SocketServer library.  How should the client 'learn' the server's ip address?  They are running in the same security group.</p>
  
  <p>In the future I hope to launch ~100 of these client-server pairs, so I wasn't sure if elastic ip addresses were a good solution.</p>
  
  <p>Thanks.</p>