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 defined with replicas: 5. You run 'kubectl scale deployment myapp --replicas=3'. Which component is responsible for ensuring the actual number of Pods matches the desired 3?
etcd
Why wrong: etcd stores the desired state but does not take action to enforce it.
Deployment controller in kube-controller-manager
The Deployment controller watches the Deployment and manages the ReplicaSet to achieve the desired number of replicas.
kubelet
Why wrong: kubelet maintains Pod lifecycle on a Node but does not scale Deployments.
kube-scheduler
Why wrong: The scheduler assigns Pods to Nodes but does not manage replica counts.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
Deployment controller in kube-controller-manager
The Deployment controller, which runs as part of the kube-controller-manager, is responsible for reconciling the desired state of a Deployment. When you run 'kubectl scale deployment myapp --replicas=3', the Deployment controller detects the change in the Deployment's replica count and creates or deletes Pods via the ReplicaSet controller to match the desired 3 replicas.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
etcd
Why it's wrong here
etcd stores the desired state but does not take action to enforce it.
Deployment controller in kube-controller-manager
Why this is correct
The Deployment controller watches the Deployment and manages the ReplicaSet to achieve the desired number of replicas.
Related concept
Read the scenario before looking for a memorised answer.
kubelet
Why it's wrong here
kubelet maintains Pod lifecycle on a Node but does not scale Deployments.
kube-scheduler
Why it's wrong here
The scheduler assigns Pods to Nodes but does not manage replica counts.
Common exam traps
CNCF often tests the misconception that kubelet or kube-scheduler handles scaling, when in fact kubelet only manages local Pod lifecycle and the scheduler only places Pods on nodes, while the Deployment controller in the kube-controller-manager is the component that reconciles replica counts.
Detailed technical explanation
The Deployment controller watches the Deployment resource via the Kubernetes API server and updates the associated ReplicaSet's replica count. The ReplicaSet controller then creates or terminates Pods to match the desired count, using the API server to write Pod objects to etcd. In a real-world scenario, if the Deployment controller fails or is misconfigured, scaling commands may appear to succeed but the actual number of Pods will not change, leading to a mismatch between desired and actual state.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
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
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
Kubernetes Fundamentals — This question tests Kubernetes Fundamentals — Read the scenario before looking for a memorised answer..
The correct answer is: Deployment controller in kube-controller-manager — The Deployment controller, which runs as part of the kube-controller-manager, is responsible for reconciling the desired state of a Deployment. When you run 'kubectl scale deployment myapp --replicas=3', the Deployment controller detects the change in the Deployment's replica count and creates or deletes Pods via the ReplicaSet controller to match the desired 3 replicas.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 30, 2026
This KCNA practice question is part of Courseiva's free CNCF certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the KCNA exam.
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