Working the same way as before.
^[a-z](-[a-z0-9](-[a-z0-9])*)?([a-z0-9]-[a-z0-9]|[a-z0-9])*(?:[a-z](-[a-z0-9](-[a-z0-9])*)?([a-z0-9]-[a-z0-9]|[a-z0-9])*)$

Working the same way as before.
^[a-z](-[a-z0-9](-[a-z0-9])*)?([a-z0-9]-[a-z0-9]|[a-z0-9])*(?:[a-z](-[a-z0-9](-[a-z0-9])*)?([a-z0-9]-[a-z0-9]|[a-z0-9])*)$
