php实现window平台的checkdnsrr函数

if (!function_exists('checkdnsrr ')) {
  function checkdnsrr($host, $type) {
    if(!empty($host) && !empty($type)) {
      @exec('nslookup -type=' . escapeshellarg($type) . ' ' . escapeshellarg($host), $output);
      foreach ($output as $k => $line) {
        if(eregi('^' . $host, $line)) {
          return true;
        }
      }
    }
    return false;
  }
}