- A
The field 'spec.selector' is missing, which is required for Deployment
The 'spec.selector' field is present and correctly configured, so option A is incorrect.
- B
The 'replicas' field is set to 0
Why wrong: The 'replicas' field is set to 3, not 0, so option B is incorrect.
- C
The 'containers' field is misspelled as 'container'
Why wrong: The 'containers' field is spelled correctly, so option C is incorrect.
- D
The 'apiVersion' should be 'v1'
Why wrong: The 'apiVersion: apps/v1' is correct for Deployment, so option D is incorrect.
Question 13 of 997
Deployment Selector — Required field for Pod Creation
This KCNA practice question tests your understanding of kubernetes fundamentals. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. A key principle to apply: spec.selector. 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.
You apply the following YAML:
apiVersion: apps/v1 kind: Deployment metadata: name: web-deploy spec: replicas: 3 selector: matchLabels: app: web template: metadata: labels: app: web spec: containers: - name: nginx image: nginx:1.21
But the Deployment never creates any Pods. Which field is missing or incorrect?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue:
"never"Why it matters: Absolute qualifier. True only if the statement has zero exceptions — be cautious of options that seem obvious but break down in edge cases.
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 field 'spec.selector' is missing, which is required for Deployment
The provided YAML is valid. The 'spec.selector' field is present and correctly matches the template labels. The 'replicas' is set to 3, not 0. 'containers' is spelled correctly, and 'apiVersion: apps/v1' is correct for Deployment. Therefore, none of the listed options describe a real issue, and the Deployment should create Pods as expected.
Key principle: spec.selector
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 field 'spec.selector' is missing, which is required for Deployment
Why this is correct
The 'spec.selector' field is present and correctly configured, so option A is incorrect.
Clue confirmation
The clue word "never" in the question point toward this answer.
Related concept
spec.selector
- ✗
The 'replicas' field is set to 0
Why it's wrong here
The 'replicas' field is set to 3, not 0, so option B is incorrect.
- ✗
The 'containers' field is misspelled as 'container'
Why it's wrong here
The 'containers' field is spelled correctly, so option C is incorrect.
- ✗
The 'apiVersion' should be 'v1'
Why it's wrong here
The 'apiVersion: apps/v1' is correct for Deployment, so option D is incorrect.
Common exam traps
Common exam trap: answer the scenario, not the keyword
CNCF often tests the misconception that the `selector` field is optional or that the `template.metadata.labels` alone suffice, but the `spec.selector` is mandatory and must match the template labels for the Deployment to function.
Detailed technical explanation
How to think about this question
The `spec.selector` is a required field for a Deployment because it defines the label query used by the ReplicaSet controller to identify and manage Pods. Without it, the Deployment controller cannot create a ReplicaSet, and the ReplicaSet controller cannot track Pods, resulting in zero Pods being created. In practice, this is a common misconfiguration when copying a Pod spec into a Deployment template without adding the selector, leading to silent failures where the Deployment exists but no Pods are ever scheduled.
KKey Concepts to Remember
- spec.selector
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
spec.selector
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. spec.selector 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.
Review spec.selector, then practise related KCNA questions on the same topic to reinforce the concept.
- →
Kubernetes Fundamentals — study guide chapter
Learn the concepts, then practise the questions
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Targeted practice on this topic area only
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FAQ
Questions learners often ask
What does this KCNA question test?
Kubernetes Fundamentals — This question tests Kubernetes Fundamentals — spec.selector.
What is the correct answer to this question?
The correct answer is: The field 'spec.selector' is missing, which is required for Deployment — The provided YAML is valid. The 'spec.selector' field is present and correctly matches the template labels. The 'replicas' is set to 3, not 0. 'containers' is spelled correctly, and 'apiVersion: apps/v1' is correct for Deployment. Therefore, none of the listed options describe a real issue, and the Deployment should create Pods as expected.
What should I do if I get this KCNA question wrong?
Review spec.selector, then practise related KCNA questions on the same topic to reinforce the concept.
Are there clue words in this question I should notice?
Yes — watch for: "never". Absolute qualifier. True only if the statement has zero exceptions — be cautious of options that seem obvious but break down in edge cases.
What is the key concept behind this question?
spec.selector
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Last reviewed: Jun 30, 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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