byte flush varnish when on a varnish cluster

multiple domains.php

<?php
  header("Cache-Control: no-cache, must-revalidate"); //HTTP 1.1

  $domains = array('devguppie.com', 'wwww.devguppie.com', 'www.example.com', 'example.com');
  foreach ($domains as $domain) {
      $curl   = curl_init("http://$domain/.*");
      curl_setopt($curl, CURLOPT_CUSTOMREQUEST, "PURGE");
      curl_exec($curl);
      curl_close($curl);
  }
?>

single domain.php

<?php
    header("Cache-Control: no-cache, must-revalidate"); //HTTP 1.1
    $domain = basename(dirname(realpath(__FILE__)));
    $curl   = curl_init("http://$domain/.*");
    curl_setopt($curl, CURLOPT_CUSTOMREQUEST, "PURGE");
    curl_exec($curl);
    curl_close($curl);
?>