<?php $value = 'ryan_test3.10.239.252.211'; var_dump(preg_match('/(?=^.{4,253}$)(^((?!-)[a-z0-9-_]{1,63}(?<!-)\.)*?((?!-)[a-z0-9-]{1,63}(?<!-)\.)[a-z]{2,63}\.?$)/i', $value));
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