Certified Kubernetes Application Developer (CKAD) Practice Test

Which of the following would indicate a pod is ready to serve traffic?

1. The pod has all initialized containers

2. The readiness probe has returned successful results

3. All containers have started without errors

4. The application within the pod is logging events

The correct answer is: The readiness probe has returned successful results

A pod being ready to serve traffic is indicated specifically by the successful results of its readiness probe. In Kubernetes, readiness probes are diagnostic checks that determine if a pod is prepared to handle requests. When the readiness probe returns successful results, it signals to the Kubernetes control plane that the application in the pod is fully started and operational, enabling it to receive traffic. While having all initialized containers and all containers started without errors are important for the overall health of a pod, they do not necessarily indicate that the application is ready for traffic. The readiness probe directly ensures that the running application meets the criteria for being serviceable, making it the definitive signal for readiness. The application's logging of events is also not a reliable indicator of readiness, as it does not reflect the operational state of the application concerning traffic handling capabilities. Thus, the best indicator of a pod's readiness is indeed the successful results of its readiness probe.