What is a probe within Kubernetes?
A monitoring mechanism of the Kubernetes API.
A pre-operational scope issued by the kubectl agent.
A diagnostic performed periodically by the kubelet on a container.
A logging mechanism of the Kubernetes API.
The Answer Is:
CExplanation:
In Kubernetes, a probe is a health check mechanism that the kubelet executes against containers, so C is correct. Probes are part of how Kubernetes implements self-healing and safe traffic management. The kubelet runs probes periodically according to the configuration in the Pod spec and uses the results to decide whether a container is healthy, ready to receive traffic, or still starting up.
Kubernetes supports three primary probe types:
Liveness probe: determines whether the container should be restarted. If liveness fails repeatedly, kubelet restarts the container (subject to restartPolicy).
Readiness probe: determines whether the Pod should receive traffic via Services. If readiness fails, the Pod is removed from Service endpoints, preventing traffic from being routed to it until it becomes ready again.
Startup probe: used for slow-starting containers. It disables liveness/readiness failures until startup succeeds, preventing premature restarts during initialization.
Probe mechanisms can be HTTP GET, TCP socket checks, or exec commands run inside the container. These checks are performed by kubelet on the node where the Pod is running, not by the API server.
Options A and D incorrectly attribute probes to the Kubernetes API. While probe configuration is stored in the API as part of Pod specs, execution is node-local. Option B is not a Kubernetes concept.
So the correct definition is: a probe is a periodic diagnostic run by kubelet to assess container health/readiness, enabling reliable rollouts, traffic gating, and automatic recovery.
=========
