This KCNA practice question tests your understanding of container orchestration. 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.
You have a Kubernetes cluster with multiple nodes. You need to ensure that a pod runs on a node that has an SSD. How should you achieve this?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Use a nodeSelector with the label 'disktype: ssd'
Option C is correct because nodeSelector is the simplest and most direct way to constrain a Pod to run only on nodes that have a specific label, such as 'disktype=ssd'. When you add a nodeSelector field to the Pod spec, the kube-scheduler filters nodes that do not have the matching label, ensuring the Pod lands on a node with an SSD.
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.
✗
Manually edit kube-scheduler configuration
Why it's wrong here
This is complex and unnecessary; nodeSelector or nodeAffinity are the standard approaches.
✗
Use a DaemonSet to run the pod on all nodes
Why it's wrong here
DaemonSet runs a pod on every node, not just those with SSDs.
✓
Use a nodeSelector with the label 'disktype: ssd'
Why this is correct
nodeSelector is a simple field that matches node labels, making it the easiest way to schedule pods on nodes with SSDs.
Related concept
Read the scenario before looking for a memorised answer.
✗
Use a toleration for the node
Why it's wrong here
Tolerations are used to allow pods to schedule on nodes with taints, not to select specific hardware.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is confusing tolerations (which allow scheduling onto tainted nodes) with node selection mechanisms like nodeSelector or nodeAffinity, leading candidates to pick D when they need a label-based constraint.
Detailed technical explanation
How to think about this question
Under the hood, nodeSelector works by matching the key-value pair against node labels set via 'kubectl label node <node-name> disktype=ssd'. The kube-scheduler's predicate phase filters out nodes that lack the label, and the priority phase scores remaining nodes; this is a simple label-based constraint, whereas nodeAffinity offers more expressive operators (In, NotIn, Exists) and soft/hard requirements. In real-world scenarios, you might combine nodeSelector with taints and tolerations to both attract Pods to SSD nodes and repel other workloads.
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.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this KCNA question in full detail.
Container Orchestration — This question tests Container Orchestration — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Use a nodeSelector with the label 'disktype: ssd' — Option C is correct because nodeSelector is the simplest and most direct way to constrain a Pod to run only on nodes that have a specific label, such as 'disktype=ssd'. When you add a nodeSelector field to the Pod spec, the kube-scheduler filters nodes that do not have the matching label, ensuring the Pod lands on a node with an SSD.
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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