$re = '/([a-zA-Z0-9-]+)(\.[a-zA-Z]{2,5})?(\.[a-zA-Z]+$)/m';
$str = 'https://domain.com
https://subdomain.domain.com
https://www.sub.sub.subdomain.domain.com
http://sub.masterdomain.com.au
https://four.submains.new.domain.luxury.co.uk
https://www.globo.us/games/tap-zap-boom/
https://www.test.com/games/socce/index.html
https://google.com.br/services/index.php
';
preg_match_all($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