How does Envoy handle unhealthy hosts during traffic management?

In Envoy's approach to traffic management, excluding unhealthy hosts from the load balancing pool is a crucial mechanism that enhances the overall reliability and performance of the service. When a host is identified as unhealthy—due to factors like failed health checks, resource constraints, or unresponsiveness—Envoy marks it as unavailable for receiving traffic.

This exclusion prevents requests from being sent to the unhealthy host, thereby ensuring that users receive responses from only those hosts that are operational and functioning correctly. By doing this, Envoy helps to maintain a seamless user experience and reduces the likelihood of failures that could arise if unhealthy hosts were still included in the pool for traffic distribution.

The other choices, while relevant to service management in some contexts, do not accurately reflect the specific mechanism used by Envoy to handle unhealthy hosts during traffic management. For example, automatically restarting hosts or notifying administrators might be part of a recovery strategy, but the immediate action taken to manage traffic is primarily through exclusion from routing. Rerouting traffic to alternate services, while a possible strategy, does not encompass the core handling of the unhealthy hosts themselves.