KCNA Container Orchestration Practice Question
A Kubernetes cluster has a Deployment running three replicas of an application. You need to update the container image to a new version with zero downtime. Which approach is most appropriate?
⚠ Common exam trap
CNCF often tests the misconception that manually deleting pods or scaling to zero is a valid zero-downtime strategy, but these actions cause service disruption because they do not maintain the desired number of available replicas during the update.
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
✓
Use 'kubectl set image deployment/<name> <container>=<new-image>' to trigger a rolling update
`kubectl set image deployment/<name> <container>=<new-image>` triggers a rolling update, which is the default update strategy for Deployments. This gradually replaces old pods with new ones, ensuring that the desired number of replicas is always available, thus achieving zero downtime.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Use 'kubectl set image deployment/<name> <container>=<new-image>' to trigger a rolling update
Why this is correct
This command updates the image and initiates a rolling update, ensuring zero downtime.
- ✗
Manually delete each pod and rely on the ReplicaSet to recreate them with the new image
Why it's wrong here
Deleting pods does not automatically update the image; the ReplicaSet would create pods with the old image unless the Deployment template is updated first.
- ✗
Delete the Deployment and recreate it with the new image
Why it's wrong here
This would cause downtime as all pods are deleted before the new ones are created.
- ✗
Scale the Deployment to zero and then scale back up with the new image
Why it's wrong here
Scaling to zero would cause downtime.
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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.