KCNA Kubernetes Fundamentals Practice Question
A Deployment is configured with 'replicas: 5' and a rolling update strategy. During an update, you notice that the number of available pods drops to 3 momentarily. Which field in the Deployment spec can be adjusted to control the minimum number of pods available during a rolling update?
⚠ Common exam trap
The exam often tests the distinction between `maxSurge` and `maxUnavailable` by describing a scenario where Pods drop below the desired count, leading candidates to mistakenly choose `maxSurge` because they confuse 'extra Pods above desired' with 'minimum Pods available'.
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.strategy.rollingUpdate.maxUnavailable
`spec.strategy.rollingUpdate.maxUnavailable` defines the maximum number (or percentage) of Pods that can be unavailable during a rolling update. With `replicas: 5`, setting `maxUnavailable: 2` would allow at most 2 Pods to be unavailable at any time, ensuring that at least 3 Pods remain available — which matches the observed drop to 3. This field directly controls the minimum number of available Pods during the update process.
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.strategy.rollingUpdate.maxSurge
Why it's wrong here
`maxSurge` controls how many extra pods can be created above the desired replica count during an update, not the minimum number that must remain available. It is tempting because it is the other half of the rolling‑update configuration alongside `maxUnavailable`, and in scenarios where you want to speed up an update by allowing extra pods to be spun up before old ones terminate, adjusting `maxSurge` would be correct. Here, however, the requirement is to prevent the available count from dropping below a threshold, which is governed solely by `maxUnavailable`.
- ✓
spec.strategy.rollingUpdate.maxUnavailable
Why this is correct
maxUnavailable controls how many pods can be unavailable during the update.
- ✗
spec.minReadySeconds
Why it's wrong here
minReadySeconds controls how long a pod must be ready before it is considered available, but does not limit the number of unavailable pods.
- ✗
spec.replicas
Why it's wrong here
Replicas sets the desired number of pods but does not control availability during updates.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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