CKAD Application Observability and Maintenance Practice Question
A pod is running but not responding to traffic. You suspect the application inside the container is unhealthy but the pod is still marked as 'Running'. Which probe should be configured to remove the pod from the service's endpoints automatically?
⚠ Common exam trap
The CKAD exam often tests the distinction between Liveness and Readiness probes, and the trap here is that candidates mistakenly choose Liveness probe because they think 'unhealthy' always means 'restart', but the question specifically asks about removing the pod from Service endpoints, which is the Readiness probe's job.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Readiness probe
A Readiness probe determines whether a container is ready to accept traffic. If the probe fails, Kubernetes removes the pod's IP address from the endpoints of all Services that match the pod's labels, effectively stopping traffic from reaching the pod while it remains in the Running state. This is the correct probe for removing an unhealthy pod from Service endpoints without terminating it.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Readiness probe
Why this is correct
The readiness probe is the only probe that directly controls whether the Pod is added to or retained in the Endpoints object backing a Service. When it fails, the kubelet marks the Pod's Ready condition as False, and the endpoints controller removes its IP from all matching Service backends, so it stops receiving new traffic while it is still running. This precisely matches the symptom of a running Pod that is unresponsive: it should be taken out of rotation, not restarted.
- ✗
Resource limits
Why it's wrong here
Resource limits are enforced by the kubelet and container runtime as CPU throttling or OOM kill thresholds, and they influence scheduling decisions via the scheduler's resource requests. They do not affect the Service Endpoints or the Ready condition; a Pod can exceed its memory limit, be OOMKilled, and still be listed as a backend until the kubelet notices the container is not running. Therefore, resource limits cannot explain why a running Pod is absent from or failing within service traffic routing.
- ✗
Startup probe
Why it's wrong here
The startup probe exists only to delay the activation of liveness and readiness probes for containers that need a long initialization time. Once the startup probe succeeds, it is stopped and never runs again, so it has no ongoing effect on the Pod's Ready condition or Service endpoint membership. A failure of the startup probe restarts the container during initialization, but after a successful startup it cannot remove the Pod from serving traffic.
- ✗
Liveness probe
Why it's wrong here
The liveness probe determines whether the container is still alive and, on failure, instructs the kubelet to restart the container; it does not update the Ready condition or the Service's Endpoints. While a container is being restarted, the Pod may remain in the endpoint list and continue to receive traffic if no readiness probe is failing, leading to connection errors during the restart window. Thus a liveness probe alone cannot be used to remove an unresponsive Pod from traffic, which is the job of a readiness probe.
Go deeper
Related to this question
About these practice questions
This CKAD question is part of Courseiva's 160-question bank — original exam-style content with full explanations and wrong-answer analysis, never real exam questions or exam dumps. Learn why practice questions differ from exam dumps →
JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This CKAD practice question is part of Courseiva's free CNCF certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the CKAD exam.