'Act as secondary for the specified domain, performing
zone transfers from the specified IP (IP/domain)'

def opt_secondary(self, ip_domain):

    args = ip_domain.split('/', 1)
    if (len(args) != 2):
        raise usage.UsageError('Argument    must    be    of    the    form    IP[:port]/domain')
    address = args[0].split(':')
    if (len(address) == 1):
        address = (address[0], dns.PORT)
    else:
        try:
            port = int(address[1])
        except ValueError:
            raise usage.UsageError(('Specify    an    integer    port    number,    not    %r' % (address[1],)))
        address = (address[0], port)
    self.secondaries.append((address, [args[1]]))
