CKA (Kubernetes) - Master Study Guide

Certified Kubernetes Administrator

Master CKA.

The definitive interactive guide for the CKA exam. Explore Kubernetes architecture and cluster management.

Architecture & Design

🏛️

K8s Architecture

Control Plane, Worker Nodes, and API Server.

🏗️

Cluster Architecture

Etcd, Scheduler, and Controller Manager.

Infrastructure & Resources

🚀

Workloads

Pods, Deployments, and StatefulSets.

🕸️

Networking

Services, Ingress, NetworkPolicies, and CNI.

💽

Storage

Persistent Volumes (PV), PVCs, and StorageClasses.

Operations

🔍

Troubleshooting

Logs, Events, JSONPATH queries, and cluster recovery.

Kubernetes Architecture Overview

The fundamental separation of duties in a K8s cluster.

🧠

Control Plane
Master Node

The Control Plane manages the worker nodes and the Pods in the cluster. In production environments, the control plane usually runs across multiple computers for high availability.

kube-apiserver

The front end of the control plane. ALL communication (from kubectl, workers, etc.) goes through the API server.

etcd

A highly-available, consistent key-value store holding the cluster's entire state. If etcd is lost, the cluster is lost. Backing up etcd is a major CKA requirement.

kube-scheduler & controller-manager

**Scheduler:** Watches for new Pods with no assigned node, and assigns them one based on resources/taints. **Controller-Manager:** Runs controllers like the Node controller (notices when nodes go down) and ReplicaSet controller.

🖥️

Worker Nodes
Compute Instances

Node components run on every node, maintaining running pods and providing the Kubernetes runtime environment.

kubelet

The primary "node agent" that runs on each node. It takes PodSpecs (provided by the API server) and ensures that the containers described in those PodSpecs are running and healthy.

kube-proxy

A network proxy that runs on each node. It maintains network rules (usually via iptables) that allow network communication to your Pods from inside or outside of your cluster.

Container Runtime

The software that actually runs the containers (e.g., containerd, CRI-O). Kubernetes removed the Docker Engine as a built-in node runtime in v1.24, but the Docker CLI and images still exist.

Cluster Architecture

Workloads & Scheduling

Pod Lifecycle States

Pending

Waiting for Scheduler

➔

ContainerCreating

Pulling images & CNI setup

➔

Running

Bound to Node & Active

Security & Access Cheat Sheet

RBAC

Roles, RoleBindings, ClusterRoles.

SecurityContext

RunAsUser, capabilities, readOnlyRootFilesystem.

NetworkPolicy

podSelector, ingress, egress, ipBlock.

Networking

🔌 Networking Ports Cheat Sheet

6443: Kubernetes API Server (Control Plane)
2379-2380: etcd server client API (Control Plane)
10250: Kubelet API (All Nodes)
30000-32767: NodePort Services default range (All Nodes)

Storage

💽 Storage Volume Types

emptyDir

Ephemeral. Erased when Pod is deleted. Good for sharing files between containers in a pod.

hostPath

Mounts directory from the host node. Data remains if pod dies, but is lost if pod moves to another node.

PersistentVolumeClaim (PVC)

Requests persistent storage from the cluster (PV) that outlives both the pod and the node.

Master CKA.

Architecture & Design

K8s Architecture

Cluster Architecture

Infrastructure & Resources

Workloads

Networking

Storage

Operations

Troubleshooting

Kubernetes Architecture Overview

Control PlaneMaster Node

kube-apiserver

etcd

kube-scheduler & controller-manager

Worker NodesCompute Instances

kubelet

kube-proxy

Container Runtime

Cluster Architecture

Workloads & Scheduling

Pod Lifecycle States

Security & Access Cheat Sheet

Networking

🔌 Networking Ports Cheat Sheet

Storage

💽 Storage Volume Types

Troubleshooting

Control Plane
Master Node

Worker Nodes
Compute Instances