KCNA Kubernetes Fundamentals Practice Question
An administrator wants to update the image of a Deployment named 'my-app' from 'nginx:1.19' to 'nginx:1.20' with a rolling update strategy. They want to ensure that during the update, the number of unavailable pods never exceeds 1. Which field should they set in the Deployment spec?
⚠ Common exam trap
A common mix-up: candidates confuse `maxSurge` with `maxUnavailable`, mistakenly thinking that controlling how many extra Pods are created (surge) also limits unavailable Pods, but `maxSurge` only caps the number of Pods above the desired count, not the number that can be unavailable.
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` controls the maximum number of Pods that can be unavailable during a rolling update. Setting this to 1 ensures that at most one Pod is unavailable at any time, meeting the administrator's requirement. This field is part of the Deployment's rolling update strategy and directly governs the availability guarantee 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.replicas
Why it's wrong here
replicas sets the desired number of pods, not the update surge/unavailable count.
- ✗
spec.minReadySeconds
Why it's wrong here
minReadySeconds is the minimum time a pod must be ready to be considered available; it does not control the number of unavailable pods during update.
- ✗
spec.strategy.rollingUpdate.maxSurge
Why it's wrong here
`spec.strategy.rollingUpdate.maxSurge` controls how many extra pods can be created above the desired replica count during a rolling update, not the number of unavailable pods. It fails here because the administrator’s requirement to cap unavailable pods at 1 is governed by `maxUnavailable`, which limits how many pods can be terminated simultaneously. This option is tempting because both fields tune rolling-update behaviour, and `maxSurge` would be correct if the goal were to control how many new pods exceed the desired count (e.g., to accelerate the rollout).
- ✓
spec.strategy.rollingUpdate.maxUnavailable
Why this is correct
maxUnavailable sets the maximum number of pods that can be unavailable during a rolling update. Setting to 1 ensures at most one pod is down at a time.
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