This CKA practice question tests your understanding of workloads & scheduling. 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 DevOps team wants to ensure that a critical application Pod is always scheduled on a node that has SSD storage. They have labeled one node with 'disk=ssd'. Which scheduling approach should they use to guarantee this placement?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "always"
Why it matters: Absolute qualifier. An answer using 'always' is only correct if there are genuinely no exceptions — absolute statements are often wrong in networking.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Add a nodeSelector with disk=ssd to the Pod spec.
Option D is correct because a `nodeSelector` is the simplest and most direct way to guarantee that a Pod is scheduled only on nodes that have a specific label. By adding `nodeSelector: disk: ssd` to the Pod spec, Kubernetes will ensure the Pod is placed exclusively on nodes with the `disk=ssd` label, which matches the labeled node. This approach is straightforward and meets the requirement without additional complexity.
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.
✗
Set nodeName in the Pod spec to the node name.
Why it's wrong here
nodeName directly assigns the Pod to a specific node, not based on labels, and is not resilient to node failures.
✗
Use nodeAffinity with requiredDuringSchedulingIgnoredDuringExecution and a matchExpression for disk=ssd.
Why it's wrong here
While this would also work, it is more complex than necessary; nodeSelector is sufficient for this simple case.
✗
Add a toleration for a taint that the node has.
Why it's wrong here
Tolerations allow scheduling on tainted nodes but do not force scheduling on a specific node.
✓
Add a nodeSelector with disk=ssd to the Pod spec.
Why this is correct
nodeSelector is the simplest way to enforce scheduling on nodes with a specific label.
Clue confirmation
The clue word "always" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often overcomplicate the solution by choosing `nodeAffinity` (option B) because it is more powerful, but the question asks for the simplest approach to guarantee placement, and `nodeSelector` is the correct and sufficient answer for a single label match.
Detailed technical explanation
How to think about this question
Under the hood, `nodeSelector` is implemented as a simplified form of node affinity that uses a `matchLabels` constraint during scheduling. The kube-scheduler evaluates the `nodeSelector` against node labels at scheduling time, and if no node matches, the Pod remains in a Pending state. In real-world scenarios, `nodeSelector` is ideal for static label-based placement, while `nodeAffinity` offers more expressive operators (e.g., `In`, `NotIn`, `Exists`) and can handle complex requirements like excluding nodes or using multiple expressions.
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 CKA 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.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this CKA question in full detail.
Workloads & Scheduling — This question tests Workloads & Scheduling — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Add a nodeSelector with disk=ssd to the Pod spec. — Option D is correct because a `nodeSelector` is the simplest and most direct way to guarantee that a Pod is scheduled only on nodes that have a specific label. By adding `nodeSelector: disk: ssd` to the Pod spec, Kubernetes will ensure the Pod is placed exclusively on nodes with the `disk=ssd` label, which matches the labeled node. This approach is straightforward and meets the requirement without additional complexity.
What should I do if I get this CKA question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Are there clue words in this question I should notice?
Yes — watch for: "always". Absolute qualifier. An answer using 'always' is only correct if there are genuinely no exceptions — absolute statements are often wrong in networking.
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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