def METHOD_NAME(self):
    """
    An argument of the form C{"ip:port/domain"} can be used to specify an
    alternate port number for which to act as a secondary.
    """
    options = Options()
    options.parseOptions(["--secondary", "1.2.3.4:5353/example.com"])
    self.assertEqual([(("1.2.3.4", 5353), ["example.com"])], options.secondaries)