KCNA Kubernetes Fundamentals Practice Question
You are asked to schedule a pod on a node that has SSD storage. Which mechanism should you use to achieve this?
⚠ Common exam trap
Watch out — candidates often confuse tolerations (which only allow scheduling on tainted nodes) with node selectors (which actively target nodes), leading them to pick D instead of C.
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
✓
Add a nodeSelector with a label matching the node, e.g., disktype: ssd
NodeSelector is the built-in Kubernetes mechanism for constraining a pod to nodes with specific labels. By labeling a node with disktype=ssd and adding that same label selector to the pod spec, the scheduler will only place the pod on nodes that have that label, ensuring it lands on SSD-equipped nodes.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Use a resource request for SSD storage capacity
Why it's wrong here
Resource requests describe CPU and memory quantities, not disk hardware characteristics; the scheduler matches nodes on capacity, so requesting storage capacity cannot select SSD-backed nodes. Extended resources would be needed to advertise such a property, making requests the right tool only for countable, schedulable resources.
- ✗
Set an annotation on the pod specifying the disk type
Why it's wrong here
Annotations carry arbitrary metadata for tooling and controllers; the scheduler ignores them entirely when filtering nodes, so an SSD annotation cannot influence placement. Annotations suit recording build versions or configuration hints for operators, not expressing hardware requirements the scheduler must enforce.
- ✓
Add a nodeSelector with a label matching the node, e.g., disktype: ssd
Why this is correct
nodeSelector pins the Pod to nodes bearing matching labels, so labelling SSD nodes disktype: ssd and referencing it in the Pod spec satisfies the SSD constraint. This differs from affinity, which expresses richer preference and topology rules.
- ✗
Add a toleration for a taint on SSD nodes
Why it's wrong here
Tolerations let a pod schedule onto a tainted node; they do not select nodes by hardware attribute. They are tempting because taints and tolerations control placement, and would be correct to permit scheduling onto a dedicated or reserved node, but SSD selection requires node affinity or a node selector.
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Same concept, more angles
1 more way this is tested on KCNA
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. Which of the following is a correct way to assign a pod to a specific node using a nodeSelector?
hard- A.spec: affinity: nodeAffinity: requiredDuringSchedulingIgnoredDuringExecution: nodeSelectorTerms: ...
- B.spec: nodeName: "node1"
- C.spec: nodeSelector: [disktype: ssd]
- ✓ D.spec: nodeSelector: disktype: ssd
Why D: `nodeSelector` is a simple pod scheduling constraint that uses a key-value pair in the `spec.nodeSelector` field to match node labels. The correct YAML syntax is `spec: nodeSelector: disktype: ssd`, where `disktype` is the label key and `ssd` is the value, ensuring the pod is scheduled only on nodes with that exact label.
JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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.