title: Do I need to specify all the host for replica Set in Mongoose, Express-session-mongo and mongolian?
body: <p>I have MongoDB replica Set as:</p>
  
  <pre><code>Host1: 10.10.10.1:27017
  Host2: 10.10.10.1:27018
  Host3: 10.10.10.2:27017
  Host4: 10.10.10.2:27018
  </code></pre>
  
  <p>When I set the connection (e.g. IN Mongoose), I have to do this:</p>
  
  <pre><code>mongoose.connectSet('mongodb://10.10.10.1:271017/mydb,
  mongodb://10.10.10.1:27018/mydb,
  mongodb://10.10.10.2:27107/mydb, mognodb://10.10.10.27108/mydb);
  </code></pre>
  
  <p>can I just do this? </p>
  
  <pre><code>mongoose.connectSet('mongodb://10.10.10.1/mydb, mongodb://10.10.10.2/mydb');
  </code></pre>
  
  <p>How about express-session-mongo and mongolian? how to set up the connection to replica set?</p>
  
  <p>Why I have to define all the host names?  shouldn't the driver know all the primary and secondary and keep the lookup table, instead of manually define it during setting up the connection?</p>