AWS Elastic Load Balancer LAB | Step-by-Step Practical | Application Load Balancer Setup|

🎯 Welcome to this hands-on AWS Elastic Load Balancer (ELB) Lab!

In this practical lab, we’ll guide you step-by-step on how to create, configure, and test an Application Load Balancer (ALB) in AWS. You’ll learn how ELB automatically distributes incoming traffic across multiple EC2 instances to ensure high availability, fault tolerance, and scalability for your applications.

🔍 In This Lab You’ll Learn:

✅ What is an Elastic Load Balancer (ELB)?
✅ How to set up an Application Load Balancer (ALB)
✅ Configuring Target Groups and Listeners
✅ Connecting EC2 Instances to the Load Balancer
✅ Verifying Load Distribution
✅ Real-world best practices for production

💡 Perfect For:

AWS Beginners and Cloud Engineers

DevOps Professionals

Students preparing for AWS Certifications

📘 Related Labs:

AWS Auto Scaling Lab

EC2 Instance Setup

S3 Static Website Hosting

AWS VPC and Subnet Configuration

⚙️ AWS Application Load Balancer (ALB) Step-by-Step Lab
🔧 Prerequisites

Before you begin, make sure you have:

VPC: A Virtual Private Cloud with at least two public subnets in different Availability Zones.

EC2 Instances: Two (or more) EC2 instances running a web app or HTML page in different AZs.

Security Group: Allows inbound traffic on Port 80 (HTTP) from the VPC CIDR range or ALB’s Security Group.

🧩 Phase 1: Create the Target Group

1️⃣ Navigate to EC2 Dashboard → “Target Groups” under Load Balancing.
2️⃣ Click Create target group → Select Instances.
3️⃣ Enter a name (e.g., web-app-tg) and set Protocol: HTTP, Port: 80.
4️⃣ Choose your VPC and configure Health Checks:

Protocol: HTTP

Path: / or /index.html

Healthy threshold: 5 | Unhealthy threshold: 2 | Interval: 30s
5️⃣ Register EC2 targets → Select your two instances → Click Include as pending → Create target group.
6️⃣ Wait until health status turns Healthy for both instances.

🌐 Phase 2: Create the Application Load Balancer (ALB)

1️⃣ Go to Load Balancers → Click Create load balancer → Select Application Load Balancer.
2️⃣ Basic Configuration:

Name: my-app-alb-2025

Scheme: Internet-facing

IP type: IPv4
3️⃣ Network Mapping:

Choose the same VPC as your Target Group

Select two public subnets in different AZs
4️⃣ Security Group:

Allow inbound HTTP (80) and HTTPS (443) from 0.0.0.0/0
5️⃣ Listeners and Routing:

Protocol: HTTP | Port: 80

Default action: Forward to your Target Group (web-app-tg)

(Optional) Add HTTPS listener with SSL certificate from ACM
6️⃣ Review & Create:

Review settings → Add tags → Click Create load balancer.

Wait until the state becomes Active.

🧪 Phase 3: Testing and Verification

✅ Get DNS Name: Copy from Load Balancer Details.
✅ Paste in a browser — you should see responses from different EC2 instances on refresh (round-robin).
✅ Health Check Test: Stop one EC2 instance → ALB removes it from routing → Traffic only goes to healthy instance.
✅ Result: Seamless failover and high availability confirmed!

🧹 Clean Up Resources

To avoid unnecessary AWS charges:

Delete the Load Balancer

Delete the Target Group

Terminate EC2 Instances

🧠 Key Takeaways

Elastic Load Balancing enhances application scalability and fault tolerance.

Application Load Balancer (ALB) supports path-based routing, host-based routing, and WebSocket support.

Perfect integration with Auto Scaling, EC2, and CloudWatch metrics.

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