$re = '/(?:(?<subdomain>[a-z0-9\.\-]*)\.)?(?<domain>(?!com)[a-z0-9\-]{3,}(?=\.[a-z\.]{2,}))\.(?:(?<tld>[a-z\.]{2,})$)/ms';
$str = 'apple.orange.banana.clevername.co.uk
strawberry.apple.orange.banana.clevername.co.uk
tangerine.com.au
simple.com
bit.ly
something.bit.ly
clevername.com.au
hello.world.ninja
www.something.cancerresearch';
preg_match_all($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