KCNA Container Orchestration Practice Question
An administrator wants to ensure that a specific pod only runs on nodes that have solid-state drives (SSDs). Nodes with SSDs are labeled with 'disktype=ssd'. Which pod specification field should be used?
⚠ Common exam trap
A common mix-up: candidates confuse `nodeSelector` with `nodeAffinity` and choose `nodeAffinity` because it sounds more powerful, but the question explicitly asks for the field that ensures a specific pod only runs on nodes with SSDs, and `nodeSelector` is the correct, minimal field for a simple label match.
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
✓
nodeSelector
The `nodeSelector` field in a Pod spec is the simplest and most direct way to constrain a Pod to nodes with specific labels. By setting `nodeSelector: { disktype: ssd }`, the scheduler will only place the Pod on nodes that have the label `disktype=ssd`, which matches the administrator's requirement exactly. This field is a hard constraint that does not support complex expressions, but it is ideal for straightforward label-based node selection.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
nodeSelector
Why this is correct
nodeSelector directly matches node labels and is the simplest approach for this requirement.
- ✗
container resource limits
Why it's wrong here
Resource limits control CPU/memory usage, not node selection.
- ✗
tolerations
Why it's wrong here
Tolerations are used to allow scheduling on tainted nodes, not to select nodes by label.
- ✗
nodeAffinity
Why it's wrong here
`nodeAffinity` is the correct *mechanism* for scheduling pods based on node labels, including the 'disktype=ssd' requirement. However, the question asks for the specific *field* within the pod specification. `nodeAffinity` is itself a sub-field of the broader `affinity` field (`spec.affinity.nodeAffinity`). While `nodeAffinity` is where the rules are defined, `affinity` is the top-level field that encapsulates all node and pod affinity/anti-affinity rules, making it the more encompassing and direct answer for the *field* to configure.
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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.