title: Should the Reverse DNS for an EC2 point to the Public DNS or the domain name?
body: <p>In trying to set up a mail server (for fun!), I <a href="https://portal.aws.amazon.com/gp/aws/html-forms-controller/contactus/ec2-email-limit-rdns-request" rel="nofollow">requested a Reverse DNS</a> from Amazon, specifying my Elastic IP and my mail server subdomain (e.g. mail.mydomain.com).<br>
  A Reverse DNS Lookup now returns my EC2 Public DNS.</p>
  
  <p>e.g.</p>
  
  <blockquote>
    <p>$ dig -x 5.4.3.2 +short<br>
    ec2-5-4-3-2.us-west-2.compute.amazonaws.com.</p>
  </blockquote>
  
  <p>I expected that the reverse lookup would instead point to my domain name ('mail.mydomain.com').</p>
  
  <p>1) Is my expectation wrong? Should a Reverse Lookup point the EC2 public DNS or to the requested domain name?<br>
  2) Is the <code>dig</code> result because I missed something? Such as additionally making a PTR record in Route53 and/or configuring something in apache (such as a proxy or alias)?</p>
  
  <p>System: I have a t2-micro (using an EIP and Route53) running ubuntu 14.04 and apache2 with a few sites. And I'm following this <a href="http://arstechnica.com/information-technology/2014/02/how-to-run-your-own-e-mail-server-with-your-own-domain-part-1/" rel="nofollow">mail server tutorial</a>.</p>
  
  <p>Thanks! There's a lot to this mail server stuff!</p>