CKAD Application Observability and Maintenance Practice Question
What is the purpose of a readiness probe in Kubernetes?
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
✓
To control whether the pod receives traffic from Services
A readiness probe determines whether a container is ready to serve traffic. If the probe fails, the pod is removed from the endpoints of Services, thus it does not receive traffic. Option B describes a startup probe (to delay liveness/readiness probes for slow-starting containers). Option C describes resource monitoring, not a probe. Option D describes a liveness probe, which restarts the container if unhealthy.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
To control whether the pod receives traffic from Services
Why this is correct
Readiness probes determine pod readiness; failing pods are removed from Service endpoint slices, so kube-proxy stops forwarding traffic to them. This directly satisfies the stem's requirement to control whether the pod receives traffic from Services, unlike liveness probes which restart containers.
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To delay the start of other probes for slow-starting containers
Why it's wrong here
A startup probe, not a readiness probe, delays other probes while a slow container initialises. Readiness probes instead control whether the Pod's IP is listed in Service endpoints, removing it from load balancing until it can serve traffic. The option confuses the two probe types, which share a handler but differ in purpose.
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To monitor resource usage of the container
Why it's wrong here
Readiness probes report application availability by returning success or failure to kubelet; they never collect CPU or memory figures. Resource usage is gathered by metrics-server and surfaced through kubectl top or HorizontalPodAutoscaler. Readiness gates Service endpoint membership, so a container exceeding limits is throttled or evicted rather than marked unready.
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To restart the container if it becomes unhealthy
Why it's wrong here
A readiness probe determines whether a container is ready to accept traffic; it does not trigger a restart. The liveness probe serves that restart function when a container becomes unhealthy. This option is tempting because both probes assess container health, but readiness only controls service endpoint inclusion, whereas liveness enforces the restart policy defined in the pod spec.
Go deeper
Related to this question
Learn chapter
Kubernetes Core Concepts and Architecture
Key term
Liveness Probes
A liveness probe is a Kubernetes health check that tells the system whether a container is running properly and should be kept alive or restarted.
Key term
Readiness Probes
A Kubernetes mechanism that checks if a container is ready to start accepting traffic and serve requests.
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Written by Johnson Ajibi, MSc IT Security
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