KCNA Kubernetes Fundamentals Practice Question
You have a Deployment named 'frontend' with 3 replicas. You want to perform a rolling update to a new container image. Which command should you use?
⚠ Common exam trap
A common mix-up: candidates confuse imperative commands like `kubectl set image` with declarative commands like `kubectl replace` or non-existent commands like `kubectl update`, leading them to pick options that either require a full manifest or are syntactically invalid.
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 set image deployment/frontend container1=nginx:1.20
The `kubectl set image` command is the correct way to perform a rolling update on a Deployment. It directly updates the container image in the pod template, triggering a rolling update where the ReplicaSet gradually replaces old pods with new ones, ensuring zero downtime. Option A specifies the exact container name and new image, which matches the required syntax for a targeted update.
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/frontend container1=nginx:1.20
Why this is correct
This command updates the image for container1 in the frontend deployment.
- ✗
kubectl replace deployment frontend --image=nginx:1.20
Why it's wrong here
'kubectl replace' replaces the resource from a file, not with a direct image flag.
- ✗
kubectl edit deployment frontend --image=nginx:1.20
Why it's wrong here
'kubectl edit' opens the manifest for editing, but the --image flag is not used with it.
- ✗
kubectl update deployment frontend --image=v2
Why it's wrong here
'kubectl update' is not a valid command.
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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.