KCNA Kubernetes Fundamentals Practice Question
A team uses a Deployment with 3 replicas and a RollingUpdate strategy. They update the container image. During the update, one of the new pods fails to start. What will happen by default?
⚠ Common exam trap
The KCNA exam often tests the misconception that a failed pod in a rolling update triggers an automatic rollback or deletion, when in fact the default behavior is to pause the update and keep old replicas running until the issue is resolved manually.
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 update pauses, keeping the remaining old replicas running
By default, a Deployment with a RollingUpdate strategy uses a `maxUnavailable` of 25% and a `maxSurge` of 25%. When a new pod fails to start (e.g., CrashLoopBackOff or ImagePullBackOff), the ReplicaSet controller will not create additional new pods beyond the surge limit, and the update will effectively pause because the new ReplicaSet cannot reach its desired replica count. The old ReplicaSet remains running with its existing pods, ensuring availability is maintained.
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 update pauses, keeping the remaining old replicas running
Why this is correct
The rolling update stops when a new pod fails, ensuring availability of old pods.
- ✗
The entire update is rolled back and all old pods are deleted
Why it's wrong here
This would cause disruption, which the controller avoids.
- ✗
The Deployment automatically rolls back to the previous image
Why it's wrong here
Automatic rollback is not default; manual intervention or a rollout undo command is needed.
- ✗
The failed pod is terminated and not retried
Why it's wrong here
The controller retries the pod creation until it succeeds or the update is paused.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This KCNA 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 KCNA exam.