This KCNA practice question tests your understanding of kubernetes fundamentals. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. 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.
A developer created a Deployment with image 'myapp:v1' and then ran 'kubectl set image deployment/myapp myapp=myapp:v2'. What is the effect of this command?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
It updates the Deployment's pod template to use the new image, triggering a rolling update.
The `kubectl set image deployment/myapp myapp=myapp:v2` command updates the pod template within the Deployment's specification to use the new image `myapp:v2`. This change triggers a rolling update, where the Deployment controller creates new pods with the updated image and gradually terminates old pods, ensuring zero downtime. The command does not affect Services, create new Deployments, or restart pods immediately without a rolling update strategy.
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.
✗
It updates the Service selector to point to pods with the new image.
Why it's wrong here
The command only changes the image in the Deployment; it does not modify Services.
✓
It updates the Deployment's pod template to use the new image, triggering a rolling update.
Why this is correct
The command modifies the Deployment's container image, initiating a rolling update.
Related concept
Read the scenario before looking for a memorised answer.
✗
It creates a new Deployment named 'v2' with the new image.
Why it's wrong here
The command updates the existing Deployment; it does not create a new one.
✗
It immediately restarts all pods with the new image.
Why it's wrong here
The update is performed as a rolling update, not an immediate restart.
Common exam traps
Common exam trap: answer the scenario, not the keyword
CNCF often tests the distinction between updating a Deployment's pod template (which triggers a rolling update) versus directly restarting pods or modifying Services, leading candidates to mistakenly think the command affects Service selectors or creates a new Deployment.
Trap categories for this question
Command / output trap
The command only changes the image in the Deployment; it does not modify Services.
Detailed technical explanation
How to think about this question
Under the hood, `kubectl set image` modifies the `spec.template.spec.containers[].image` field in the Deployment's stored object in etcd. The Deployment controller detects the change in the pod template hash and creates a new ReplicaSet with the updated image, while scaling down the old ReplicaSet according to the `maxSurge` and `maxUnavailable` parameters (default 25% each). This mechanism ensures that the rolling update respects PodDisruptionBudgets and maintains application availability during the update.
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 small business has 20 workstations on the 192.168.1.0/24 network and one public IP from its ISP. The router uses PAT (NAT overload) so all 20 devices share one public address using different source ports. NAT questions test whether you understand the four address terms and which direction each translation applies.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this KCNA question in full detail.
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: It updates the Deployment's pod template to use the new image, triggering a rolling update. — The `kubectl set image deployment/myapp myapp=myapp:v2` command updates the pod template within the Deployment's specification to use the new image `myapp:v2`. This change triggers a rolling update, where the Deployment controller creates new pods with the updated image and gradually terminates old pods, ensuring zero downtime. The command does not affect Services, create new Deployments, or restart pods immediately without a rolling update strategy.
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.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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