KCNA Kubernetes Fundamentals Practice Question
Which TWO of the following are control plane components? (Select TWO)
⚠ Common exam trap
A common mistake is to think that kube-proxy or kubelet are control plane components because they are essential for cluster operation. However, they run on each node and are part of the node-level components, not the control plane.
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
✓
etcd
In Kubernetes, the control plane is the set of components that make global cluster decisions and store cluster state, and etcd (A) is correct because it is the consistent, highly-available key-value store that persists all cluster data, including objects, configuration, and state. The kube-apiserver (B) is also correct because it is the central control plane component that exposes the Kubernetes API, validates and processes REST requests, and is the only component that talks directly to etcd. By contrast, kube-proxy (C) runs on each node and implements Service networking rules via iptables/IPVS, kubelet (D) is the node agent that manages Pods and containers on a worker node, and the container runtime (E) is the node-level software (e.g., containerd, CRI-O) that actually runs containers — all three are node components, not control plane components.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
etcd
Why this is correct
etcd is the control plane's distributed key-value store, persisting all cluster state and configuration. It runs alongside the API server on control plane nodes, satisfying the stem's requirement for a control plane component rather than a worker node process such as kubelet or kube-proxy.
- ✓
kube-apiserver
Why this is correct
kube-apiserver is the control plane's front end, exposing the Kubernetes API that all clients and internal components communicate through. It validates and persists objects to etcd, directly satisfying the stem's requirement for a control plane component rather than a per-node worker process.
- ✗
kube-proxy
Why it's wrong here
kube-proxy runs on each node, programming iptables or IPVS rules to forward Service traffic to Pods — that is data plane work, not control plane. It tempts because it is a core Kubernetes component that maintains network state, but it would be the right answer when asked which components run on worker nodes.
- ✗
kubelet
Why it's wrong here
Kubelet runs on each node, registering it with the API server and managing pod lifecycles — that is node-level data plane work, not control plane. It is tempting because kubelet is essential to cluster operation, but it belongs to the worker node; control plane components such as the API server, scheduler and etcd make cluster-wide decisions.
- ✗
Container runtime
Why it's wrong here
Container runtime executes containers on a node, placing it in the data plane rather than the control plane. It is tempting because Kubernetes cannot run workloads without it, and it is the correct answer when asked about node-level components such as kubelet, kube-proxy or CRI implementations.
Go deeper
Related to this question
Learn chapter
Cluster Architecture and Lifecycle Management
Key term
Pods and Containers
Pods are the smallest deployable units in Kubernetes that wrap one or more containers, sharing network and storage resources.
Key term
ReplicaSet and Replication
A ReplicaSet ensures a specified number of identical pod instances are running at all times in Kubernetes, using replication to maintain availability and stability.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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