KCNA Kubernetes Fundamentals Practice Question
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?
⚠ Common exam trap
It's easy for candidates to 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.
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
`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.
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.
- ✗
kubectl rollout pause deployment/my-deployment
Why it's wrong here
This pauses the rollout but does not undo it.
Go deeper
Related to this question
About these practice questions
Courseiva writes every KCNA question from scratch — 833 in total, each with an explanation and a wrong-answer breakdown. None are copied from real exams or dumps. Learn why practice questions differ from exam dumps →
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.