- A
The Deployment will create a new ReplicaSet and gradually replace old pods with new ones
This is the default rolling update behavior: a new ReplicaSet is created, and pods are gradually transitioned.
- B
All existing pods will be deleted immediately and new pods will be created with the new image
Why wrong: That describes a Recreate update strategy, not the default RollingUpdate.
- C
The command will fail because you cannot update a Deployment using kubectl set image
Why wrong: kubectl set image is a valid way to update the image of a Deployment.
- D
The Deployment's image will be updated, but only the container named 'app' will be affected
Why wrong: The command specifies 'frontend' as the container name, not 'app'.
Question 267 of 997
Kubernetes Deployment Rolling Update Behavior
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 cluster administrator needs to ensure that a Deployment named 'frontend' in namespace 'web' is updated with a new image version using a rolling update strategy. The current deployment has 4 replicas. The administrator runs: kubectl set image deployment/frontend frontend=nginx:1.21 -n web. Which of the following describes the expected behavior?
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
✓
The Deployment will create a new ReplicaSet and gradually replace old pods with new ones
Option A is correct because `kubectl set image deployment/frontend frontend=nginx:1.21 -n web` updates the container image in the Deployment's pod template, triggering a rolling update. The Deployment controller creates a new ReplicaSet with the updated image and gradually scales it up while scaling down the old ReplicaSet, ensuring zero downtime and maintaining the desired replica count of 4.
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.
- ✓
The Deployment will create a new ReplicaSet and gradually replace old pods with new ones
Why this is correct
This is the default rolling update behavior: a new ReplicaSet is created, and pods are gradually transitioned.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
All existing pods will be deleted immediately and new pods will be created with the new image
Why it's wrong here
That describes a Recreate update strategy, not the default RollingUpdate.
- ✗
The command will fail because you cannot update a Deployment using kubectl set image
Why it's wrong here
kubectl set image is a valid way to update the image of a Deployment.
- ✗
The Deployment's image will be updated, but only the container named 'app' will be affected
Why it's wrong here
The command specifies 'frontend' as the container name, not 'app'.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates may confuse the container name in the command (which must match the container name in the Deployment spec) with a generic name like 'app', leading them to incorrectly assume only a container named 'app' is affected.
Trap categories for this question
Command / output trap
The command specifies 'frontend' as the container name, not 'app'.
Detailed technical explanation
How to think about this question
Under the hood, the Deployment controller uses a ReplicaSet-based rollout mechanism. When `kubectl set image` modifies the pod template, the controller creates a new ReplicaSet with the new image and adjusts the desired replica count of the old and new ReplicaSets according to the `maxSurge` and `maxUnavailable` parameters (defaults: 25% and 25%, respectively). This ensures that during the update, the total number of pods never exceeds 125% of the desired replicas and the number of unavailable pods never exceeds 25% of the desired replicas, maintaining application availability.
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.
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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: The Deployment will create a new ReplicaSet and gradually replace old pods with new ones — Option A is correct because `kubectl set image deployment/frontend frontend=nginx:1.21 -n web` updates the container image in the Deployment's pod template, triggering a rolling update. The Deployment controller creates a new ReplicaSet with the updated image and gradually scales it up while scaling down the old ReplicaSet, ensuring zero downtime and maintaining the desired replica count of 4.
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.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
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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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