KCNA Kubernetes Fundamentals Practice Question
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?
⚠ Common exam trap
A common mix-up: candidates 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.
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
✓
Rolling update strategy in the Deployment
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.
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.
- ✗
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.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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