KCNA Kubernetes Fundamentals Practice Question
When creating a Deployment, you want to ensure that only a certain number of pods run at a time across all nodes. Which field in the Deployment spec controls this?
⚠ Common exam trap
Watch out — candidates often confuse `spec.replicas` with `spec.selector`, thinking the selector controls the number of Pods, but the selector only determines which Pods are managed, not how many.
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
✓
spec.replicas
The `spec.replicas` field in a Deployment spec defines the desired number of identical Pod replicas that should be running at any given time. This field directly controls the count of Pods across all nodes in the cluster, ensuring that exactly that many Pods are maintained by the ReplicaSet controller. Option A is correct because it is the only field that sets the target Pod count.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
spec.replicas
Why this is correct
`spec.replicas` declares the desired number of identical pod replicas the ReplicaSet maintains cluster-wide, so the Deployment controller continuously reconciles actual pod count towards it across all nodes. This directly satisfies the stem's constraint of limiting how many pods run concurrently, independent of node placement.
- ✗
spec.selector
Why it's wrong here
spec.selector determines which existing pods the Deployment's ReplicaSet manages, matching labels rather than capping counts. It is correct when adopting or targeting pods by label. Restricting how many pods run concurrently across nodes is controlled by the rolling update strategy fields, not label selection.
- ✗
spec.minReadySeconds
Why it's wrong here
spec.minReadySeconds is the delay before a newly created pod counts as available for rollout progress, affecting readiness accounting only. It is correct when slow-starting containers need a grace period. It does not limit how many pods run at once; that is set by the rolling update strategy.
- ✗
spec.template
Why it's wrong here
spec.template is the pod template describing containers, images and labels for created pods; it sets no concurrency ceiling. It would be the right field when defining what each replica runs. Limiting simultaneous pods across nodes is governed by the strategy's rolling update parameters, not the template.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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