$re = '/^([a-z-]+|[\w]+)\.(((?!\.s1).+\.)?(co1|az1|ut1|eng|au1)\.(qprod|qops)\.net)$/m';
$str = 'test-app.az1.qprod.net
jwm12535.s1.az1.qprod.net
testing2.eng.qops.net
kvm1.c1.co1.qprod.net
bs1.co1.qprod.net
staging.s1.co1.qprod.net
staging.co1.qprod.net
server.s1.co1.qprod.net
s1.co1.qprod.net
server2.co1.qprod.net
s.co1.qprod.net
testing.az1.qprod.net
something1.eng.qops.net';
preg_match_all($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