This KCNA practice question tests your understanding of kubernetes fundamentals. 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 cluster has a node with the taint 'node-role.kubernetes.io/control-plane:NoSchedule'. A pod must be scheduled on this node for a special workload. Which action is required?
Use a nodeSelector to select the node.
Why wrong: Incorrect; nodeSelector cannot bypass taints.
Remove the taint from the node.
Why wrong: Incorrect; removing the taint allows all pods, not just the special one.
Add a toleration to the pod spec.
Correct; toleration allows the pod to be scheduled on the tainted node.
Use podAffinity to attract the pod to the node.
Why wrong: Incorrect; affinity does not override taints.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
Add a toleration to the pod spec.
Option C is correct because a taint on a node causes the scheduler to avoid placing pods on that node unless the pod explicitly tolerates the taint. By adding a toleration in the pod spec that matches the taint key, effect, and optionally the value, the pod becomes eligible to be scheduled on the tainted node. This is the standard Kubernetes mechanism for allowing pods to run on control-plane or other specially tainted nodes.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
Use a nodeSelector to select the node.
Why it's wrong here
Incorrect; nodeSelector cannot bypass taints.
Remove the taint from the node.
Why it's wrong here
Incorrect; removing the taint allows all pods, not just the special one.
Add a toleration to the pod spec.
Why this is correct
Correct; toleration allows the pod to be scheduled on the tainted node.
Related concept
Read the scenario before looking for a memorised answer.
Use podAffinity to attract the pod to the node.
Why it's wrong here
Incorrect; affinity does not override taints.
Common exam traps
The trap here is that candidates confuse nodeSelector (label-based) with tolerations (taint-based), thinking that selecting a node by label can override a taint, when in fact taints are a separate, higher-priority scheduling constraint.
Detailed technical explanation
Taints and tolerations work together as a scheduling constraint: the node's taint (e.g., 'node-role.kubernetes.io/control-plane:NoSchedule') repels pods without a matching toleration. The toleration in the pod spec must include the same key, effect, and optionally the value (e.g., tolerations: - key: node-role.kubernetes.io/control-plane, operator: Exists, effect: NoSchedule). In real-world scenarios, this is commonly used to reserve control-plane nodes for system components like CoreDNS or the ingress controller, while allowing critical workloads to opt in via tolerations.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
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.
What to study next
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FAQ
Kubernetes Fundamentals — This question tests Kubernetes Fundamentals — Read the scenario before looking for a memorised answer..
The correct answer is: Add a toleration to the pod spec. — Option C is correct because a taint on a node causes the scheduler to avoid placing pods on that node unless the pod explicitly tolerates the taint. By adding a toleration in the pod spec that matches the taint key, effect, and optionally the value, the pod becomes eligible to be scheduled on the tainted node. This is the standard Kubernetes mechanism for allowing pods to run on control-plane or other specially tainted nodes.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 11, 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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