EKS cluster creation in AWS - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Architecture

intermediate

EKS Cluster Networking Setup

You want to create an EKS cluster that supports worker nodes in multiple Availability Zones for high availability. Which networking setup is required?

A Create a VPC with subnets in multiple Availability Zones but disable routing between subnets.

B Create a VPC with a single subnet in one Availability Zone and assign private IPs only.

C Create a VPC with subnets in multiple Availability Zones and enable public IP assignment for worker nodes.

D Create a VPC with subnets in multiple Availability Zones but only use one subnet for worker nodes.

💡 Hint

Think about how worker nodes communicate and how availability zones affect fault tolerance.

For high availability, worker nodes must be spread across multiple Availability Zones. This requires subnets in each zone. Public IPs allow nodes to communicate with the internet if needed.

❓ Configuration

intermediate

IAM Role for EKS Worker Nodes

Which IAM role policy is necessary for EKS worker nodes to join the cluster and communicate with the control plane?

A AmazonEKSClusterPolicy, AmazonEC2ContainerRegistryFullAccess, AmazonVPCFullAccess

B AmazonS3FullAccess, AmazonEC2FullAccess, AmazonEKSClusterPolicy

C AmazonEKSServicePolicy, AmazonEC2FullAccess, AmazonS3ReadOnlyAccess

D AmazonEKSWorkerNodePolicy, AmazonEC2ContainerRegistryReadOnly, AmazonEKS_CNI_Policy

💡 Hint

Focus on policies that allow nodes to register and pull container images.

Worker nodes need AmazonEKSWorkerNodePolicy to join the cluster, AmazonEC2ContainerRegistryReadOnly to pull images, and AmazonEKS_CNI_Policy for networking.

❓ security

advanced

EKS Cluster Endpoint Access Control

You want to restrict access to your EKS cluster API endpoint so only specific IP addresses can connect. Which configuration achieves this?

A Enable public endpoint access and configure the allowed CIDR blocks with the IP addresses.

B Enable private endpoint access only and disable public endpoint access.

C Disable both public and private endpoint access and use a VPN to connect.

D Enable public endpoint access without CIDR restrictions and rely on security groups.

💡 Hint

Consider how EKS allows IP-based filtering on the API endpoint.

Enabling public endpoint access with allowed CIDR blocks restricts API access to specified IP ranges, controlling who can connect.

❓ service_behavior

advanced

EKS Cluster Auto Scaling Behavior

When you enable the Cluster Autoscaler on your EKS cluster, what behavior should you expect when pod resource requests increase?

A The autoscaler automatically upgrades the cluster control plane to improve performance.

B The autoscaler adds new nodes to the cluster to meet pod resource demands automatically.

C The autoscaler stops scheduling new pods until resources free up.

D The autoscaler deletes existing pods to reduce resource usage.

💡 Hint

Think about how autoscaling helps with resource shortages.

The Cluster Autoscaler adds nodes when pods cannot be scheduled due to insufficient resources, ensuring workload demands are met.

✅ Best Practice

expert

EKS Cluster Logging Configuration

You want to enable detailed logging for your EKS cluster to monitor API calls, authentications, and scheduler events. Which logging configuration is correct?

A Enable all control plane logs: API server, audit, authenticator, controller manager, and scheduler logs.

B Enable only API server logs to reduce storage costs.

C Enable worker node logs only, as control plane logs are managed by AWS.

D Disable all logging to improve cluster performance.

💡 Hint

Consider which logs provide comprehensive cluster activity visibility.

Enabling all control plane logs gives full visibility into cluster operations, which is best for monitoring and troubleshooting.

Practice

1.

What is the main purpose of creating an Amazon EKS cluster?

easy

A. To store large amounts of data in the cloud

B. To run Kubernetes applications without managing the underlying servers

C. To create virtual machines for running Windows applications

D. To manage user access and permissions in AWS

Solution

1. Step 1: Understand EKS cluster purpose

   Amazon EKS is a managed Kubernetes service that lets you run containerized applications without managing servers.

2. Step 2: Compare options

   Options A, B, and D describe other AWS services or functions unrelated to EKS clusters.

3. Final Answer:

   To run Kubernetes applications without managing the underlying servers -> Option B

4. Quick Check:

   EKS = Managed Kubernetes service [OK]

Hint: EKS runs Kubernetes without server management [OK]

Common Mistakes:

• Confusing EKS with EC2 virtual machines
• Thinking EKS is for data storage
• Mixing EKS with IAM user management

2.

Which of the following is the correct AWS CLI command to create an EKS cluster named my-cluster with role ARN arn:aws:iam::123456789012:role/EKSRole and subnets subnet-abc123 and subnet-def456?

easy

A. aws eks create-cluster --cluster-name my-cluster --role arn:aws:iam::123456789012:role/EKSRole --vpc-config subnets=subnet-abc123,subnet-def456

B. aws eks create-cluster --name my-cluster --role-arn arn:aws:iam::123456789012:role/EKSRole --resources-vpc-config subnetIds=subnet-abc123 subnet-def456

C. aws eks create-cluster --name my-cluster --role-arn arn:aws:iam::123456789012:role/EKSRole --resources-vpc-config subnetIds=subnet-abc123,subnet-def456

D. aws eks create-cluster --name my-cluster --role arn:aws:iam::123456789012:role/EKSRole --resources-vpc-config subnetIds=subnet-abc123,subnet-def456

Solution

1. Step 1: Check AWS CLI syntax for EKS cluster creation

   The correct command uses --name for cluster name, --role-arn for IAM role, and --resources-vpc-config subnetIds=... for subnet IDs separated by commas.

2. Step 2: Identify correct option

   aws eks create-cluster --name my-cluster --role-arn arn:aws:iam::123456789012:role/EKSRole --resources-vpc-config subnetIds=subnet-abc123,subnet-def456 matches the correct syntax exactly. Options A and D use incorrect flags (--cluster-name, --role). aws eks create-cluster --name my-cluster --role-arn arn:aws:iam::123456789012:role/EKSRole --resources-vpc-config subnetIds=subnet-abc123 subnet-def456 misses a comma between subnet IDs.

3. Final Answer:

   aws eks create-cluster --name my-cluster --role-arn arn:aws:iam::123456789012:role/EKSRole --resources-vpc-config subnetIds=subnet-abc123,subnet-def456 -> Option C

4. Quick Check:

   Correct CLI syntax = aws eks create-cluster --name my-cluster --role-arn arn:aws:iam::123456789012:role/EKSRole --resources-vpc-config subnetIds=subnet-abc123,subnet-def456 [OK]

Hint: Use --name, --role-arn, and comma-separated subnetIds [OK]

Common Mistakes:

• Using --role instead of --role-arn
• Missing commas between subnet IDs
• Using wrong flag names like --cluster-name

3.

Given this AWS CLI command to create an EKS cluster:

aws eks create-cluster --name test-cluster --role-arn arn:aws:iam::123456789012:role/EKSRole --resources-vpc-config subnetIds=subnet-11111111,subnet-22222222,securityGroupIds=sg-12345678

What will happen after running this command?

medium

A. The command will fail due to incorrect subnet ID format

B. The command will fail because security groups cannot be specified during cluster creation

C. The cluster will be created but only in one subnet ignoring the second subnet

D. The cluster test-cluster will be created using the specified subnets and security group

Solution

1. Step 1: Understand parameters in the command

   The command specifies cluster name, IAM role, subnet IDs, and security group IDs correctly using --resources-vpc-config.

2. Step 2: Check if security groups are allowed

   Security groups can be specified during cluster creation to control network access. The subnet IDs are comma-separated and valid format.

3. Final Answer:

   The cluster test-cluster will be created using the specified subnets and security group -> Option D

4. Quick Check:

   Valid subnet and security group syntax = The cluster test-cluster will be created using the specified subnets and security group [OK]

Hint: Security groups allowed in --resources-vpc-config [OK]

Common Mistakes:

• Thinking security groups can't be set at creation
• Assuming only one subnet is allowed
• Confusing subnet ID format with invalid syntax

4.

You tried to create an EKS cluster with this command:

aws eks create-cluster --name mycluster --role-arn arn:aws:iam::123456789012:role/EKSRole --resources-vpc-config subnetIds=subnet-12345 subnet-67890

The command failed. What is the most likely cause?

medium

A. Missing comma between subnet IDs in subnetIds parameter

B. Incorrect IAM role ARN format

C. Cluster name mycluster is invalid

D. Subnets are in different availability zones

Solution

1. Step 1: Review subnetIds parameter format

   The subnet IDs must be comma-separated inside the subnetIds= value. Here, a space separates them, which is invalid syntax.

2. Step 2: Check other parameters

   The IAM role ARN format looks correct, cluster name is valid, and subnets in different zones are recommended, not an error.

3. Final Answer:

   Missing comma between subnet IDs in subnetIds parameter -> Option A

4. Quick Check:

   Comma separates subnet IDs [OK]

Hint: Comma separate subnet IDs, not spaces [OK]

Common Mistakes:

• Using spaces instead of commas between subnet IDs
• Assuming cluster name rules cause failure
• Confusing subnet zones with errors

5.

You want to create a highly available EKS cluster. Which setup is best practice for the network configuration?

• Use a single subnet in one availability zone
• Use multiple subnets in different availability zones
• Use only public subnets
• Use subnets without any security groups

hard

A. Use multiple subnets in different availability zones

B. Use a single subnet in one availability zone

C. Use only public subnets

D. Use subnets without any security groups

Solution

1. Step 1: Understand high availability in EKS

   High availability means the cluster stays up even if one zone fails. Using multiple subnets in different availability zones achieves this.

2. Step 2: Evaluate other options

   Single subnet risks zone failure. Only public subnets expose resources unnecessarily. Subnets without security groups lack network protection.

3. Final Answer:

   Use multiple subnets in different availability zones -> Option A

4. Quick Check:

   Multi-AZ subnets = High availability [OK]

Hint: Spread subnets across zones for reliability [OK]

Common Mistakes:

• Using only one subnet risking downtime
• Exposing cluster on public subnets unnecessarily
• Ignoring security groups for network safety