Q. How do I redirect my domain name using a php server side scripting under Apache web server?

A. Under PHP you need to use header() to send a raw HTTP header.

If you want to redirect a domain to some other URL, you can use the PHP script as below

<?php
header("Location: http://example.com/");
exit();
?>

See PHP Redirect To Another URL / Page Script FAQ for further information.

source here