KCNA — Kubernetes Architecture
Chapter 2 — Kubernetes Architecture
This chapter covers Kubernetes Fundamentals, the largest KCNA exam domain at 46% weight. Understanding the architecture is the foundation for everything else.
What You’ll Learn
| # | Topic | What You’ll Understand |
|---|---|---|
| 1 | What Is Kubernetes? | Why K8s exists and the problems it solves |
| 2 | Control Plane Components | API server, etcd, scheduler, controller manager |
| 3 | Worker Node Components | kubelet, kube-proxy, container runtime |
| 4 | The Kubernetes API | How everything communicates |
| 5 | Cluster Networking Overview | Pod-to-Pod, Pod-to-Service, CNI basics |
| 6 | Container Runtime Interface | CRI, containerd, CRI-O, OCI |
| 7 | Practice Questions | Test your knowledge (10 MCQs) |
Why This Chapter Matters
Kubernetes Architecture maps directly to the Kubernetes Fundamentals domain (46% of the exam). Nearly half of your exam questions will test concepts from this chapter.
| Concept | Exam Relevance |
|---|---|
| Control plane components | What each component does, where it runs |
| Worker node components | Role of kubelet, kube-proxy, container runtime |
| API server | How kubectl commands reach the cluster |
| etcd | What happens when etcd fails |
| Networking model | Pod-to-Pod communication, CNI plugins |
| Container runtimes | CRI standard, containerd vs CRI-O |
Architecture at a Glance
┌─────────────────────────── Kubernetes Cluster ───────────────────────────┐
│ │
│ ┌──────────── Control Plane ────────────┐ │
│ │ │ │
│ │ ┌─────────────┐ ┌───────────────┐ │ │
│ │ │ API Server │ │ etcd │ │ │
│ │ └──────┬──────┘ └───────────────┘ │ │
│ │ │ │ │
│ │ ┌──────┴──────┐ ┌───────────────┐ │ │
│ │ │ Scheduler │ │ Controller │ │ │
│ │ │ │ │ Manager │ │ │
│ │ └─────────────┘ └───────────────┘ │ │
│ └───────────────────────────────────────┘ │
│ │ │
│ ┌───────────┴───────────┐ │
│ ▼ ▼ │
│ ┌─── Worker Node 1 ───┐ ┌─── Worker Node 2 ───┐ │
│ │ │ │ │ │
│ │ kubelet │ │ kubelet │ │
│ │ kube-proxy │ │ kube-proxy │ │
│ │ container runtime │ │ container runtime │ │
│ │ │ │ │ │
│ │ ┌─Pod─┐ ┌─Pod─┐ │ │ ┌─Pod─┐ ┌─Pod─┐ │ │
│ │ │ C1 │ │ C2 │ │ │ │ C3 │ │ C4 │ │ │
│ │ └─────┘ └─────┘ │ │ └─────┘ └─────┘ │ │
│ └──────────────────────┘ └──────────────────────┘ │
│ │
└──────────────────────────────────────────────────────────────────────────┘
Chapter Flow
- Start with What Is Kubernetes to understand the “why”
- Learn the Control Plane — the brain of the cluster
- Learn the Worker Nodes — where your apps actually run
- Understand the Kubernetes API — how all components communicate
- Explore Cluster Networking — how pods talk to each other
- Understand Container Runtimes — the interface between K8s and containers
- Test yourself with Practice Questions
