KCNA Container Orchestration Practice Question
What is the purpose of a readiness probe in a Kubernetes pod?
⚠ Common exam trap
The exam often tests the confusion between liveness and readiness probes, where candidates mistakenly think a readiness probe restarts the container or that both probes serve the same purpose.
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 check if the container is ready to accept traffic
A readiness probe in Kubernetes determines whether a container is ready to start accepting traffic. If the probe fails, the container is removed from the Service's endpoints, ensuring no traffic is routed to an unready pod. This is distinct from a liveness probe, which checks if the container is alive and should be restarted.
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 check if the container is alive and restart it if not
Why it's wrong here
Liveness probes perform the restart-on-failure role described here. A readiness probe instead controls whether the pod's IP is listed in the Service's Endpoints, removing it from load balancing without restarting the container. The described behaviour would be correct for a liveness probe, not a readiness probe.
- ✗
To verify the container's CPU and memory usage
Why it's wrong here
CPU and memory usage are reported by metrics-server and consumed by the Horizontal Pod Autoscaler or resource limits, not by probes. A readiness probe issues an HTTP, TCP or exec check to decide whether the pod should receive Service traffic. Resource-usage verification would be the correct focus when configuring HPA targets or LimitRange quotas.
- ✗
To ensure the container can write to persistent storage
Why it's wrong here
Readiness probes determine whether a pod should receive traffic by testing application responsiveness, removing it from Service endpoints when failing. Storage writability is not their concern; a probe checking disk access would not gate load balancing. Liveness probes handle restarting unhealthy containers.
- ✓
To check if the container is ready to accept traffic
Why this is correct
A readiness probe determines whether the container has finished starting and can serve requests; until it succeeds, the pod is removed from Service endpoints, so no traffic is routed to it. This directly satisfies the stem's requirement of readiness to accept traffic.
Go deeper
Related to this question
Learn chapter
Container Orchestration Essentials
Key term
Kubernetes API Primitives
Kubernetes API Primitives are the basic building blocks that the Kubernetes API uses to represent and manage the state of a cluster, such as Pods, Services, Deployments, and Namespaces.
Key term
ReplicaSet and Replication
A ReplicaSet ensures a specified number of identical pod instances are running at all times in Kubernetes, using replication to maintain availability and stability.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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