def is_agent_listening(self, host, port):
        """
        Check if the Instana Agent is listening on <host> and <port>.
        """
        try:
            rv = False
            url = "http://%s:%s/" % (host, port)
            response = self.client.get(url, timeout=0.8)

            server_header = response.headers["Server"]
            if server_header == AGENT_HEADER:
                logger.debug("Host agent found on %s:%d" % (host, port))
                rv = True
            else:
                logger.debug("...something is listening on %s:%d but it's not the Instana Agent: %s"
                             % (host, port, server_header))
        except (requests.ConnectTimeout, requests.ConnectionError):
            logger.debug("No host agent listening on %s:%d" % (host, port))
            rv = False
        finally:
            return rv