How to Create ELB in AWS with EC2 Instances in Different Availability Zones (Step-by-Step Guide)

April 1, 2026 by [email protected]

Flow:
User → ELB (ALB Listener) → Target Group → EC2 Instances (in different AZs)

📌 Introduction

In this guide, you will learn how to:

• Launch 2 EC2 instances in different Availability Zones
• Create a Target Group
• Configure an Application Load Balancer (ELB)
• Distribute traffic for high availability

We will use:

• Amazon EC2
• Elastic Load Balancing

🔹 Step 1: Launch EC2 Instances (in Different AZs)

🛠️ Create First Instance (AZ-1)

1. Go to EC2 Dashboard → Launch Instance
2. Name: web-server-1
3. AMI: Amazon Linux
4. Instance type: t2.micro
5. Select Availability Zone (e.g., ap-south-1a)
6. Security Group:
   • Allow HTTP (80)
   • Allow SSH (22)

👉 User Data:

#!/bin/bash
yum update -y
yum install -y httpd
systemctl enable httpd
systemctl start httpd
echo "Server 1 - AZ1 Working" > /var/www/html/index.html

🛠️ Create Second Instance (AZ-2)

Repeat same steps:

• Name: web-server-2
• Availability Zone: ap-south-1b

👉 User Data:

#!/bin/bash
yum update -y
yum install -y httpd
systemctl enable httpd
systemctl start httpd
echo "Elb and auto scalling second server working " > /var/www/html/index.html

🔹 Step 2: Create Target Group

1. Go to EC2 → Target Groups
2. Click Create Target Group

⚙️ Configuration:

• Target type: Instances
• Name: my-target-group
• Protocol: HTTP
• Port: 80
• VPC: Select your VPC

👉 Health Check:

• Path: /
• Protocol: HTTP

👉 Register Targets:

• Select both instances (web-server-1, web-server-2)
• Click Include as pending
• Click Create Target Group

🔹 Step 3: Create Application Load Balancer (ELB)

1. Go to EC2 → Load Balancers
2. Click Create Load Balancer
3. Choose: Application Load Balancer

⚙️ Basic Settings:

• Name: my-alb
• Scheme: Internet-facing
• IP type: IPv4

⚙️ Network Mapping:

• Select at least 2 subnets (different AZs)

⚙️ Security Group:

• Allow HTTP (Port 80)

⚙️ Listener:

• Protocol: HTTP
• Port: 80

⚙️ Routing:

• Select existing Target Group: my-target-group

👉 Click Create Load Balancer

🔹 Step 4: Verify Health Check

• Go to Target Group → Targets
• Status should be: Healthy ✅

👉 If not:

• Check Apache is running
• Check port 80 open

🔹 Step 5: Test Load Balancer

1. Copy Load Balancer DNS
2. Paste in browser

👉 Output will switch between:

• Server 1 - AZ1 Working
• Server 2 - AZ2 Working

👉 This confirms:
✅ Load balancing working
✅ Multi-AZ setup working