$re = '/^(?:(?:(?:.*\.)?windowsupdate|(?:.*\.)?update|download|ntservicepack|go|(?:.|dl)+\.delivery\.mp)\.microsoft|(?:.|download\.)+windowsupdate|wustat\.windows)\.com$/mi';
$str = 'windowsupdate.microsoft.com
wildcard.windowsupdate.microsoft.com
wildcard.update.microsoft.com
download.microsoft.com
ntservicepack.microsoft.com
go.microsoft.com
dl.delivery.mp.microsoft.com
dl.delivery.mp.microsoft.com
wildcard.delivery.mp.microsoft.com
wildcard.delivery.mp.microsoft.com
wildcard.windowsupdate.com
download.windowsupdate.com
wildcard.download.windowsupdate.com
wustat.windows.com';
preg_match_all($re, $str, $matches, PREG_SET_ORDER, 0);
// Print the entire match result
var_dump($matches);
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php