$re = '/[A-Za-z0-9.]*NSAADS\.[A-Za-z0-9.]*/';
$str = '1.NSAADS.com
NSAADS.1.com
www.microsoft.com
sdfsafdsadf.NSAADS.tw.
blabla.NSAADS.yaddiydda.com';
preg_match_all($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