- A
kubectl set image deployment/my-deployment nginx=nginx:1.21
Why wrong: This sets a new image but does not perform a rollback; it would create a new revision.
- B
kubectl delete deployment/my-deployment --cascade=false
Why wrong: This deletes the Deployment but leaves pods; not a rollback.
- C
kubectl rollout undo deployment/my-deployment
This command rolls back the Deployment to the previous revision.
- D
kubectl rollout pause deployment/my-deployment
Why wrong: This pauses the rollout but does not undo it.
Question 146 of 997
Rollback Deployment — kubectl rollout undo for CrashLoopBackOff
This KCNA practice question tests your understanding of kubernetes fundamentals. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
You create a Deployment with 'replicas: 3' and update the pod template to use a new image. After the rollout, you notice that the new ReplicaSet has 3 pods but they are all failing with 'CrashLoopBackOff'. You want to rollback to the previous working revision. Which command should you run?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue:
"which command"Why it matters: Tests specific CLI syntax. Recall the exact command and its required context — near-synonyms and partial matches are common distractors.
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
✓
kubectl rollout undo deployment/my-deployment
Option C is correct because `kubectl rollout undo deployment/my-deployment` reverts the Deployment to the previous revision, which is the standard Kubernetes method to roll back a failed rollout. This command restores the pod template from the last working ReplicaSet, effectively undoing the change that caused the CrashLoopBackOff.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
kubectl set image deployment/my-deployment nginx=nginx:1.21
Why it's wrong here
This sets a new image but does not perform a rollback; it would create a new revision.
- ✗
kubectl delete deployment/my-deployment --cascade=false
Why it's wrong here
This deletes the Deployment but leaves pods; not a rollback.
- ✓
kubectl rollout undo deployment/my-deployment
Why this is correct
This command rolls back the Deployment to the previous revision.
Clue confirmation
The clue word "which command" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
kubectl rollout pause deployment/my-deployment
Why it's wrong here
This pauses the rollout but does not undo it.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates confuse `kubectl rollout undo` with `kubectl set image` or `kubectl rollout pause`, thinking that manually setting the old image or pausing the rollout will revert the changes, but only `undo` actually triggers a rollback to a previous revision in the Deployment's history.
Detailed technical explanation
How to think about this question
Kubernetes Deployments maintain a revision history of ReplicaSets, and `kubectl rollout undo` defaults to the previous revision (revision-1). Under the hood, the Deployment controller scales down the current ReplicaSet and scales up the previous one, ensuring a smooth transition. In real-world scenarios, this is critical for rapid incident recovery, as it avoids manual image reversion and preserves the rollout history for auditing.
KKey Concepts to Remember
- Read the scenario before looking for a memorised answer.
- Find the constraint that changes the correct option.
- Eliminate answers that are true in general but not in this case.
TExam Day Tips
- Watch for words such as best, first, most likely and least administrative effort.
- Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A practitioner preparing for the KCNA exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
- →
Kubernetes Fundamentals — study guide chapter
Learn the concepts, then practise the questions
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FAQ
Questions learners often ask
What does this KCNA question test?
Kubernetes Fundamentals — This question tests Kubernetes Fundamentals — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: kubectl rollout undo deployment/my-deployment — Option C is correct because `kubectl rollout undo deployment/my-deployment` reverts the Deployment to the previous revision, which is the standard Kubernetes method to roll back a failed rollout. This command restores the pod template from the last working ReplicaSet, effectively undoing the change that caused the CrashLoopBackOff.
What should I do if I get this KCNA question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Are there clue words in this question I should notice?
Yes — watch for: "which command". Tests specific CLI syntax. Recall the exact command and its required context — near-synonyms and partial matches are common distractors.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
About these practice questions
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Last reviewed: Jul 4, 2026
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.
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