'Probe tls-sni-01 challenge certificate.
:param unicode domain:'

def probe_cert(self, domain, **kwargs):

    if ('host' not in kwargs):
        host = socket.gethostbyname(domain)
        logger.debug('%s    resolved    to    %s', domain, host)
        kwargs['host'] = host
    kwargs.setdefault('port', self.PORT)
    kwargs['name'] = self.z_domain
    return crypto_util.probe_sni(**kwargs)
