Kubernetes architecture (control plane and nodes) - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to identify the main component of the Kubernetes control plane that manages the cluster state.

Kubernetes

The Kubernetes control plane component responsible for storing cluster data is called [1].

Drag options to blanks, or click blank then click option'

Aetcd

Bkube-proxy

Ckubelet

Dcontainer runtime

Attempts:

3 left

💡 Hint

Common Mistakes

Confusing kubelet with etcd

Thinking kube-proxy stores data

The etcd is the key-value store that holds all cluster data in Kubernetes control plane.

2fill in blank

medium

Complete the code to name the Kubernetes node component that runs containers and communicates with the control plane.

Kubernetes

The agent running on each Kubernetes node that manages pods and containers is called [1].

Drag options to blanks, or click blank then click option'

Akube-proxy

Betcd

Ckubelet

DAPI server

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing kube-proxy with kubelet

Thinking API server runs on nodes

The kubelet runs on each node and ensures containers are running as expected.

3fill in blank

hard

Fix the error in the statement about the Kubernetes control plane component that exposes the Kubernetes API.

Kubernetes

The component that exposes the Kubernetes API and serves as the front-end of the control plane is called [1].

Drag options to blanks, or click blank then click option'

Ascheduler

Bkube-proxy

Ckubelet

DAPI server

Attempts:

3 left

💡 Hint

Common Mistakes

Confusing scheduler with API server

Thinking kube-proxy exposes API

The API server is the front-end of the Kubernetes control plane that exposes the API.

4fill in blank

hard

Fill both blanks to complete the description of Kubernetes node networking components.

Kubernetes

The component [1] manages network rules on nodes, while [2] runs containers and reports node status.

Drag options to blanks, or click blank then click option'

Akube-proxy

Bkubelet

Cetcd

DAPI server

Attempts:

3 left

💡 Hint

Common Mistakes

Swapping kubelet and kube-proxy roles

Including etcd as a node component

kube-proxy manages network rules for pod communication, and kubelet runs containers and reports node health.

5fill in blank

hard

Fill all three blanks to complete the dictionary comprehension describing control plane components and their roles.

Kubernetes

control_plane = {"[1]": "Stores cluster data", "[2]": "Schedules pods", "[3]": "Exposes Kubernetes API"}

Drag options to blanks, or click blank then click option'

Aetcd

Bscheduler

CAPI server

Dkubelet

Attempts:

3 left

💡 Hint

Common Mistakes

Using kubelet instead of scheduler

Mixing up API server and etcd roles

etcd stores data, scheduler assigns pods to nodes, and API server exposes the API.

Practice

1. Which component of Kubernetes is responsible for deciding what runs and where?

easy

A. Container runtime

B. Node

C. Pod

D. Control plane

Solution

1. Step 1: Understand Kubernetes architecture roles

   The control plane manages the cluster and makes decisions about scheduling and managing workloads.

2. Step 2: Identify the component that schedules workloads

   The control plane includes the scheduler which decides what runs and where.

3. Final Answer:

   Control plane -> Option D

4. Quick Check:

   Control plane = workload decision maker [OK]

Hint: Control plane manages; nodes run workloads [OK]

Common Mistakes:

• Confusing nodes with control plane
• Thinking containers decide scheduling
• Mixing pods with control plane

2. Which of the following is a correct component of the Kubernetes control plane?

easy

A. etcd

B. kube-proxy

C. kubelet

D. containerd

Solution

1. Step 1: List control plane components

   Control plane includes etcd, kube-apiserver, kube-controller-manager, and kube-scheduler.

2. Step 2: Identify which option is part of control plane

   etcd stores cluster data and is part of the control plane.

3. Final Answer:

   etcd -> Option A

4. Quick Check:

   etcd = control plane data store [OK]

Hint: etcd stores data in control plane [OK]

Common Mistakes:

• Confusing kubelet as control plane
• Thinking kube-proxy is control plane
• Mixing container runtime with control plane

3. Given a Kubernetes cluster, which component runs on each node to ensure containers are running properly?

medium

A. kubelet

B. kube-apiserver

C. kube-scheduler

D. etcd

Solution

1. Step 1: Identify node components

   Nodes run components like kubelet and kube-proxy to manage containers and networking.

2. Step 2: Determine which component manages container lifecycle on nodes

   kubelet runs on each node and ensures containers are running as expected.

3. Final Answer:

   kubelet -> Option A

4. Quick Check:

   kubelet = node container manager [OK]

Hint: kubelet runs on nodes to manage containers [OK]

Common Mistakes:

• Confusing kube-apiserver as node component
• Thinking scheduler runs on nodes
• Mixing etcd with node components

4. You notice pods are not starting on a node. Which component should you check first for errors on that node?

medium

A. kube-scheduler

B. kubelet

C. kube-apiserver

D. etcd

Solution

1. Step 1: Understand pod startup process

   Pods are started and managed on nodes by the kubelet component.

2. Step 2: Identify component to check for node pod issues

   Since pods fail to start on a node, kubelet logs and status should be checked first.

3. Final Answer:

   kubelet -> Option B

4. Quick Check:

   kubelet manages pods on nodes [OK]

Hint: Check kubelet logs for node pod issues [OK]

Common Mistakes:

• Checking scheduler instead of kubelet
• Looking at etcd for node pod errors
• Confusing apiserver with node issues

5. In a Kubernetes cluster, if the control plane node fails, which of the following is true?

hard

A. New pods can still be scheduled on nodes

B. Nodes automatically become control planes

C. Existing pods continue running but no new scheduling occurs

D. All pods immediately stop running

Solution

1. Step 1: Understand control plane failure impact

   The control plane manages scheduling and cluster state but nodes run pods independently.

2. Step 2: Analyze pod behavior when control plane is down

   Existing pods keep running on nodes, but no new pods can be scheduled without control plane.

3. Final Answer:

   Existing pods continue running but no new scheduling occurs -> Option C

4. Quick Check:

   Control plane down = no new scheduling, pods run [OK]

Hint: Control plane down stops scheduling, not running pods [OK]

Common Mistakes:

• Thinking pods stop immediately
• Assuming nodes become control planes
• Believing new pods schedule without control plane