Question 166 of 997

Kubernetes Fundamentals →hardMultiple ChoiceObjective-mapped

Troubleshooting Deployment RollingUpdate: How maxSurge and maxUnavailable Affect Pod Termination

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 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?

Clue words in this question

Noticing these words before you look at the options changes how you read each choice.

Clue: "most likely"
Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.

A
The Deployment's 'paused' field is set to true
Why wrong: If paused, no Pods would be created or terminated.
B
The Deployment's 'revisionHistoryLimit' is set to 1
Why wrong: This affects history, not rollout behavior.
C
maxSurge and maxUnavailable are set to values that allow termination of old Pods before new ones are ready
For example, maxSurge=1 and maxUnavailable=1 allows the rollout to continue even if new Pods are unhealthy, potentially terminating old ones.
D
The RollingUpdate strategy has maxSurge=0 and maxUnavailable=0
Why wrong: This would prevent any change.

Full breakdown with real-world context →

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

Option C is correct because 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.

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.

✗
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.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
The RollingUpdate strategy has maxSurge=0 and maxUnavailable=0
Why it's wrong here
This would prevent any change.

Common exam traps

Common exam trap: answer the scenario, not the keyword

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.

Detailed technical explanation

How to think about this question

Under the hood, the Kubernetes Deployment controller uses a ReplicaSet-based rolling update where maxSurge controls how many extra Pods can be created above the desired count, and maxUnavailable controls how many Pods can be unavailable during the update. If maxUnavailable is set to a value like 25% (or 1), the controller will terminate old Pods to meet that threshold even if the new Pods are failing readiness probes, because it prioritizes maintaining the allowed number of unavailable Pods over waiting for new Pods to become healthy. This behavior can lead to a complete outage if the new Pods never become ready, as the controller will continue terminating old Pods until the desired replica count is met with unhealthy new Pods, which are then terminated by the kubelet due to failed health checks.

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.

What to study next

Got this wrong? Here's your next step.

Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.

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FAQ

Questions learners often ask

What does this KCNA question test?

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: maxSurge and maxUnavailable are set to values that allow termination of old Pods before new ones are ready — Option C is correct because 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.

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.

Are there clue words in this question I should notice?

Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.

What is the key concept behind this question?

Read the scenario before looking for a memorised answer.

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