This KCNA practice question tests your understanding of kubernetes fundamentals. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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 team is designing a Kubernetes cluster for a production workload that requires high availability. They have three worker nodes in different availability zones. Which statement about scheduling Pods is correct?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Define a Pod topology spread constraint with topologyKey: topology.kubernetes.io/zone.
Option D is correct because a Pod topology spread constraint with `topologyKey: topology.kubernetes.io/zone` explicitly instructs the scheduler to distribute Pods evenly across the specified failure domains (availability zones). This ensures that if one zone fails, the remaining zones still have running Pods, achieving high availability for the production workload.
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.
✗
Use nodeSelector to assign Pods to nodes in different zones.
Why it's wrong here
nodeSelector only matches labels; it does not ensure spreading across zones.
✗
Add tolerations for the zone taint.
Why it's wrong here
Tolerations allow scheduling on tainted nodes but do not spread Pods.
✗
Use podAntiAffinity with a requiredDuringSchedulingIgnoredDuringExecution rule.
Why it's wrong here
Anti-affinity ensures Pods are not on the same node, but does not guarantee zone distribution.
✓
Define a Pod topology spread constraint with topologyKey: topology.kubernetes.io/zone.
Why this is correct
Topology spread constraints explicitly spread Pods across zones for high availability.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Cisco often tests the distinction between mechanisms that merely allow placement (tolerations, nodeSelector) versus those that enforce distribution (topology spread constraints), leading candidates to confuse permission with active scheduling policy.
Detailed technical explanation
How to think about this question
Under the hood, the topology spread constraint uses the `topologyKey` to define the domain (e.g., zone) and can be combined with `maxSkew` to control imbalance tolerance. The scheduler evaluates all nodes and attempts to minimize skew across the specified topology domains, using a best-effort or required enforcement depending on `whenUnsatisfiable`. In a real-world scenario, if you have three zones and three replicas, the constraint will aim to place one Pod per zone, but if a zone has no schedulable nodes (e.g., due to resource exhaustion), the scheduler may violate the constraint if `whenUnsatisfiable: ScheduleAnyway` is set.
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.
Kubernetes Fundamentals — This question tests Kubernetes Fundamentals — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Define a Pod topology spread constraint with topologyKey: topology.kubernetes.io/zone. — Option D is correct because a Pod topology spread constraint with `topologyKey: topology.kubernetes.io/zone` explicitly instructs the scheduler to distribute Pods evenly across the specified failure domains (availability zones). This ensures that if one zone fails, the remaining zones still have running Pods, achieving high availability for the production workload.
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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