KCNA Container Orchestration Practice Question
A Deployment manages 3 replicas of a pod. During a rolling update, one of the new pods enters CrashLoopBackOff. What happens next?
⚠ Common exam trap
CNCF often tests the misconception that a Deployment automatically rolls back on failure, but in reality, it only pauses after a progress deadline, requiring manual rollback or correction.
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 Deployment pauses the rollout and waits for manual intervention
By default, a Deployment's rolling update strategy has a `progressDeadlineSeconds` setting (default 600 seconds) and a `maxUnavailable`/`maxSurge` configuration. When a new pod enters CrashLoopBackOff, the Deployment's controller detects that the update is not making progress (the new ReplicaSet cannot reach the desired replica count with healthy pods). After the progress deadline expires, the Deployment marks the rollout as failed and pauses the update, requiring manual intervention (e.g., `kubectl rollout undo` or fixing the pod template). This behavior is governed by the Deployment controller's reconciliation loop and the `Progressing` condition.
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 Deployment deletes all pods and recreates them
Why it's wrong here
That would cause downtime and is not default behavior.
- ✗
The Deployment automatically reverts to the previous ReplicaSet
Why it's wrong here
Auto-rollback is not default; it requires a Deployment with revisionHistoryLimit and manual rollback.
- ✗
The Deployment continues the rollout, ignoring the failure
Why it's wrong here
The Deployment will stop the rollout if the new pod is not healthy.
- ✓
The Deployment pauses the rollout and waits for manual intervention
Why this is correct
The Deployment controller will not proceed with the update if the new pod fails readiness checks.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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