KCNA Kubernetes Fundamentals Practice Question
A production issue arises: a Deployment with 10 replicas is updated, but the new Pods are failing health checks and being terminated. The old Pods are also being terminated. What is the most likely cause?
⚠ Common exam trap
A common misconception is that maxSurge and maxUnavailable only control scaling speed, not the order of Pod termination, leading candidates to overlook that aggressive values can cause old Pods to be terminated before new ones are healthy.
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
✓
maxSurge and maxUnavailable are set to values that allow termination of old Pods before new ones are ready
When maxSurge and maxUnavailable are set to values that allow termination of old Pods before new ones are ready, the RollingUpdate strategy can scale down old ReplicaSets even if the new Pods are failing health checks. This happens because maxUnavailable defines the maximum number of Pods that can be unavailable during the update, and if set to a value like 1 (or a percentage), the controller will terminate old Pods to meet that threshold, even if the new Pods are not yet healthy. The result is a cascading failure where both old and new Pods are terminated, leading to a service disruption.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
The Deployment's 'paused' field is set to true
Why it's wrong here
If paused, no Pods would be created or terminated.
- ✗
The Deployment's 'revisionHistoryLimit' is set to 1
Why it's wrong here
This affects history, not rollout behavior.
- ✓
maxSurge and maxUnavailable are set to values that allow termination of old Pods before new ones are ready
Why this is correct
For example, maxSurge=1 and maxUnavailable=1 allows the rollout to continue even if new Pods are unhealthy, potentially terminating old ones.
- ✗
The RollingUpdate strategy has maxSurge=0 and maxUnavailable=0
Why it's wrong here
This would prevent any change.
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Written by Johnson Ajibi, MSc IT Security
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