CKA Practice Question: Cluster Architecture, Installation and Configuration
Which of the following is a core control plane component responsible for persisting cluster state?
⚠ Common exam trap
Watch out — candidates often confuse the kube-apiserver as the storage component because it is the only component that talks to etcd, but the actual persistence layer is etcd itself.
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
etcd is the core control plane component responsible for persisting cluster state. It is a distributed, consistent key-value store that stores all cluster data, including configuration, state, and metadata. The kube-apiserver is the only component that interacts directly with etcd, ensuring that all state changes are recorded durably.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
kube-apiserver
Why it's wrong here
The kube-apiserver is the stateless front-end for the cluster: it authenticates, authorizes, and processes RESTful requests, but it never persists data locally. It validates objects and writes them to etcd, making it the gateway, not the database. If the API server is restarted, it rebuilds its cache from etcd, confirming it holds no durable cluster state.
- ✗
kube-scheduler
Why it's wrong here
The kube-scheduler is a control loop that only decides which node should receive a pending Pod. It reads Pod and Node information from the API server, evaluates constraints like resource requests and taints, then writes a binding object back — but stores nothing itself. Its decisions are ephemeral and re-derivable, so a scheduler restart loses no cluster data; the binding lives in etcd, not in the scheduler.
- ✗
kube-controller-manager
Why it's wrong here
The kube-controller-manager runs controllers (Deployment, ReplicaSet, ServiceAccount, etc.) that continuously reconcile actual state with desired state. These controllers watch resources via the API server and issue updates, but they do not maintain their own storage layer. All durable cluster state remains in etcd; the controller manager is effectively stateless and can be restarted without data loss.
- ✓
etcd
Why this is correct
etcd is the consistent, highly-available distributed key-value store that acts as the cluster’s single source of truth. It persists every Kubernetes object — Secrets, ConfigMaps, Pod specs, and cluster configuration — using the Raft consensus algorithm to replicate writes across all etcd members. This is the only core control-plane component that actually stores data, making it critical for backup and disaster recovery.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This CKA 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 CKA exam.