title: PHP $_SERVER['HOST_NAME'] return ELB address with AWS ELB + EC2
body: <p>I am using AWS CloudFront -> ELB -> 2 x EC2 instance and I have setup pointed my domain www.mydomain.net to the domain of CF.  CF will cache the returns of ELB.  ELB connected to 2 EC2 instance (Web1 and Web2).</p>
  
  <p>I have a PHP script that use <code>$_SERVER['HOST_NAME']</code>, but it doesn't return <code>www.mydomain.net</code>, it returns the ELB domain name. </p>
  
  <p>How can I set it return www.mydomain.net?</p>