Cross-zone load balancing in AWS - Mini Project: Build & Apply

Enable Cross-Zone Load Balancing on an AWS Application Load Balancer

📖 Scenario: You are managing a web application hosted on AWS. To improve availability and distribute traffic evenly, you use an Application Load Balancer (ALB) across multiple Availability Zones.By default, the ALB routes traffic to targets in the same zone as the request. To optimize traffic distribution, you want to enable cross-zone load balancing.

🎯 Goal: Configure an AWS Application Load Balancer to enable cross-zone load balancing using AWS CLI commands.

📋 What You'll Learn

Create an Application Load Balancer named my-alb in two Availability Zones

Create a target group named my-target-group

Register two targets with the target group

Enable cross-zone load balancing on the Application Load Balancer

💡 Why This Matters

🌍 Real World

Cross-zone load balancing helps distribute incoming traffic evenly across multiple Availability Zones, improving application availability and fault tolerance.

💼 Career

Cloud architects and DevOps engineers often configure load balancers with cross-zone load balancing to optimize resource utilization and ensure high availability.

1

Create the Application Load Balancer

Use the AWS CLI command to create an Application Load Balancer named my-alb in the subnets subnet-123abc and subnet-456def. Include the security group sg-789xyz, specify the type as application, and specify the scheme as internet-facing.

AWS

# Use aws elbv2 create-load-balancer command with the specified name, subnets, security groups, type, and scheme
# Your code here

Need a hint?

Use the aws elbv2 create-load-balancer command with the required parameters.

2

Create the Target Group

Create a target group named my-target-group for instances using the protocol HTTP and port 80. Use the VPC ID vpc-abc123.

AWS

aws elbv2 create-load-balancer --name my-alb --type application --subnets subnet-123abc subnet-456def --security-groups sg-789xyz --scheme internet-facing
# Use aws elbv2 create-target-group command with the specified name, protocol, port, and VPC ID
# Your code here

Need a hint?

Use the aws elbv2 create-target-group command with the required parameters.

3

Register Targets with the Target Group

Register two instance targets with IDs i-0123456789abcdef0 and i-0fedcba9876543210 to the target group named my-target-group on port 80.

AWS

aws elbv2 create-load-balancer --name my-alb --type application --subnets subnet-123abc subnet-456def --security-groups sg-789xyz --scheme internet-facing
aws elbv2 create-target-group --name my-target-group --protocol HTTP --port 80 --vpc-id vpc-abc123
# Use aws elbv2 register-targets command to add the two instances to my-target-group
# Your code here

Need a hint?

Use the aws elbv2 register-targets command with the target group ARN and target instance IDs.

4

Enable Cross-Zone Load Balancing

Enable cross-zone load balancing on the Application Load Balancer named my-alb by modifying its attributes using the AWS CLI.

AWS

aws elbv2 create-load-balancer --name my-alb --type application --subnets subnet-123abc subnet-456def --security-groups sg-789xyz --scheme internet-facing
aws elbv2 create-target-group --name my-target-group --protocol HTTP --port 80 --vpc-id vpc-abc123
aws elbv2 register-targets --target-group-arn arn:aws:elasticloadbalancing:region:account-id:targetgroup/my-target-group/1234567890abcdef --targets Id=i-0123456789abcdef0 Id=i-0fedcba9876543210
# Use aws elbv2 modify-load-balancer-attributes to enable cross-zone load balancing for my-alb
# Your code here

Need a hint?

Use the aws elbv2 modify-load-balancer-attributes command with the correct attribute key and value.