This KCNA practice question tests your understanding of kubernetes fundamentals. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. 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.
You have a Deployment named 'web-app' that manages 3 replicas. You need to update the container image from version 1.0 to 2.0 with zero downtime. Which Kubernetes feature is designed to handle this automatically when you update the Deployment's pod template?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Rolling update strategy in the Deployment
The correct answer is B because a Deployment's default update strategy is 'RollingUpdate', which automatically replaces old Pods with new ones in a controlled manner, ensuring zero downtime by incrementally scaling down old replicas and scaling up new replicas. When you update the container image in the Deployment's pod template, Kubernetes triggers a rolling update that maintains the desired number of replicas throughout the process.
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.
✗
ReplicationController
Why it's wrong here
ReplicationController is the older predecessor to ReplicaSet and does not support rolling updates.
✓
Rolling update strategy in the Deployment
Why this is correct
The rolling update strategy is the default update strategy for Deployments, enabling gradual pod replacement with zero downtime.
Related concept
Read the scenario before looking for a memorised answer.
✗
DaemonSet
Why it's wrong here
DaemonSet ensures one pod per node, but does not have a built-in rolling update mechanism for zero-downtime image updates.
✗
StatefulSet's onDelete strategy
Why it's wrong here
StatefulSet's onDelete strategy requires manual pod deletion for updates, not automatic zero-downtime rolling updates.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates may confuse the Deployment's automatic rolling update with manual update methods (like onDelete) or think that a ReplicationController or DaemonSet can handle zero-downtime updates in the same way, but only the Deployment's RollingUpdate strategy provides this out-of-the-box behavior for stateless applications.
Detailed technical explanation
How to think about this question
Under the hood, the Deployment controller uses a ReplicaSet for each revision of the pod template; during a rolling update, it creates a new ReplicaSet with the desired image version and gradually scales it up while scaling down the old ReplicaSet, respecting the 'maxSurge' and 'maxUnavailable' parameters (defaults: 25% and 25%). This ensures that the total number of available Pods never drops below the desired count minus maxUnavailable, and the total number of Pods never exceeds the desired count plus maxSurge, enabling zero-downtime updates even under load.
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.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this KCNA question in full detail.
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: Rolling update strategy in the Deployment — The correct answer is B because a Deployment's default update strategy is 'RollingUpdate', which automatically replaces old Pods with new ones in a controlled manner, ensuring zero downtime by incrementally scaling down old replicas and scaling up new replicas. When you update the container image in the Deployment's pod template, Kubernetes triggers a rolling update that maintains the desired number of replicas throughout the process.
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.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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