KCNA Kubernetes Fundamentals Practice Question
A developer runs `kubectl get pods` and notices that one Pod is stuck in the `Pending` state. The Pod's resource requests are modest, and the node has sufficient CPU and memory. Which of the following is the MOST likely reason the Pod is not being scheduled?
⚠ Common exam trap
The trap here is assuming that Pending always means insufficient resources, while ignoring scheduling constraints like nodeSelector or affinity.
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
✓
The Pod has a nodeSelector that does not match any node's labels.
The scheduler assigns Pods to nodes based on resource requests, node selectors, affinity rules, and taints/tolerations. When a Pod remains Pending despite adequate resources, a nodeSelector mismatch is a common cause. The scheduler cannot find a node that satisfies the label constraint, so it leaves the Pod unscheduled until a suitable node becomes available or the selector is corrected.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
The Pod's service account does not exist.
Why it's wrong here
A missing service account would cause the Pod to fail at creation or be stuck in a different error state, not Pending. The scheduler does not check service accounts when assigning Pods to nodes, so this would not prevent scheduling.
- ✗
The Pod's container image is not available in the registry.
Why it's wrong here
An unavailable image would cause the Pod to be stuck in ImagePullBackOff or ErrImagePull after being scheduled, not Pending. The Pending phase indicates the Pod has not been assigned to a node yet, so image issues are not the cause.
- ✗
The Pod's liveness probe is failing.
Why it's wrong here
A failing liveness probe would cause the container to restart repeatedly, but the Pod would still be scheduled and running. The Pending state means the Pod hasn't been scheduled, so probe failures are irrelevant to this scenario.
- ✓
The Pod has a nodeSelector that does not match any node's labels.
Why this is correct
A nodeSelector restricts scheduling to nodes with matching labels. If no node has the specified label, the scheduler cannot place the Pod, leaving it Pending. Other factors like resource availability are not the issue here, so this is the most likely cause.
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Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official CNCF exam blueprint
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