AWS Elastic Load Balancer

 

AWS Elastic Load Balancer (ELB) – Step-by-Step Guide

Elastic Load Balancer (ELB) is an AWS service that automatically distributes incoming application traffic across multiple EC2 instances. It improves application availability, fault tolerance, and scalability by spreading traffic across different Availability Zones.

Step 1: Create the First EC2 Instance

Create the first EC2 instance as usual.

While creating the instance, make sure to configure the following:

  • Name: Server_01

  • Key Pair: Select or create a key pair

  • Security Group: Allow required ports

  • Availability Zone: Select an Availability Zone

  • Application Setup: Configure your application in Advanced Details (if needed)

Step 2: Create the Second EC2 Instance with Security Group

Create a second EC2 instance and configure a new Security Group.

Inbound Rules:

  • HTTP – Port 80 – Source: 0.0.0.0/0

  • HTTPS – Port 443 – Source: 0.0.0.0/0

  • SSH – Port 22 – Source: Your IP

Important Points:

  • Edit the Network Settings

  • Select a different Availability Zone from Server_01

  • Both servers must be in the same AWS region

Name this instance:

  • Server_02

This setup ensures high availability across Availability Zones.

Step 3: Verify Availability Zones

At this stage:

  • Server_01 is in Availability Zone A

  • Server_02 is in Availability Zone B

Both instances are in the same region but different Availability Zones, which is essential for fault tolerance.

Step 4: Create a Target Group

  1. Go to EC2 → Target Groups

  2. Click Create target group

  3. Choose:

    • Target type: Instance

    • Protocol: HTTP

    • Port: 80

  4. Provide a name (example: web-target-group)

  5. Register targets:

    • Select Server_01 and Server_02

    • Click Include as pending

    • Create the target group

Ensure the instances show Healthy status.

Step 5: Create the Load Balancer

  1. Go to EC2 → Load Balancers

  2. Click Create Load Balancer

  3. Select Application Load Balancer

  4. Configure:

    • Load Balancer name

    • Scheme: Internet-facing

    • IP address type: IPv4

  5. Select multiple subnets (Availability Zones)

  6. Select the Security Group allowing HTTP/HTTPS traffic

  7. Configure the listener:

    • HTTP (80) → Forward to the target group

  8. Create the Load Balancer

AWS will now create a Load Balancer with two backend servers.

Step 6: Access the Application Using Load Balancer

Once the Load Balancer is active, copy the DNS name provided by AWS:

http://<load-balancer-dns-name>

Use this DNS name in the browser instead of individual server IPs.

Step 7: Scaling – Adding a Third Server

When traffic increases, a new server can be added easily.

Create Server_03:

  • Launch a new EC2 instance

  • Choose a new Availability Zone

  • Use the same application and Security Group

Add Server_03 to Target Group:

  1. Go to Target Groups

  2. Select the existing target group

  3. Click Register targets

  4. Select Server_03

  5. Include as pending and save

Update Load Balancer Subnets:

  • Go to Load Balancer → Edit subnets

  • Add the subnet of Server_03’s Availability Zone

Once health checks pass, Server_03 will start receiving traffic automatically.

Conclusion

AWS Elastic Load Balancer distributes traffic across multiple EC2 instances located in different Availability Zones. This improves application availability, ensures fault tolerance, and allows seamless scaling as traffic increases.

Using ELB is a best practice for building highly available and scalable applications on AWS.

Date : 17Dec2025

Comments

Post a Comment

Popular posts from this blog

Managing Amazon EBS Volumes and Snapshots Across Regions

  Managing Amazon EBS Volumes and Snapshots Across Regions In this blog, we’ll walk through how to create, modify, snapshot, copy, and attach Amazon EBS volumes across different AWS regions (from ap-south-2 Hyderabad to ap-south-1 Mumbai ). 1. Creating an EC2 Instance and Increasing Volume Size Create an EC2 instance as usual. During or after instance creation, go to Storage . Select the attached volume. Click Actions → Modify Volume . Increase the volume size as required. ⚠️ Note: EBS volume size can only be increased , not decreased. 2. Creating a New EBS Volume Go to EC2 Dashboard → Volumes . Click Create Volume . Provide: Volume name Volume size Availability Zone Click Create Volume . This will create a standalone EBS volume. 3. Attaching the Volume to an Instance Select the created volume. Click Actions → Attach Volume . Select the target EC2 instance. Attach the volume. The volume is now connected to the in...
Read more

Git for Beginners: Complete Guide from Installation to First Push on GitHub

Git Basics: Download, Install, Create Files, Commit, and Push to GitHub Git is a distributed version control system that helps developers track changes in source code and collaborate effectively. In this post, you will learn everything from downloading Git on Windows to pushing your code to GitHub . 1️⃣ Download and Install Git on Windows Follow these steps to download and install Git on a Windows machine: Open your browser and go to: https://git-scm.com Click Download for Windows Run the downloaded installer During installation: Keep the default options Select “Git from the command line and also from 3rd-party software” Complete the installation Verify Git Installation Open Command Prompt or Git Bash and run: git --version 2️⃣ Configure Git (Mandatory Step) ⚠️ Without configuring username and email, commits will not happen. git config --global user.name "Ghouse Shaik" git config --global user.email "ghouseshaik1272@gmail.com" Verify configuration: git config --l...
Read more

AWS - Amazon Web Services

  AWS (Amazon Web Services) is Amazon’s cloud computing platform. Launched in 2006 as one of the first major cloud service providers. Founded under Amazon by Jeff Bezos . Offers 200+ cloud services including compute, storage, networking, security, AI/ML, DevOps, and analytics. Operates on a global infrastructure with Regions , Availability Zones , and Edge Locations . Known as the largest and most widely used cloud platform in the world. Uses a pay-as-you-go pricing model , making it cost-efficient and highly scalable. ⭐ Top Most Important AWS Services EC2 (Elastic Compute Cloud) – Virtual servers for running applications. S3 (Simple Storage Service) – Scalable, durable object storage used everywhere. IAM (Identity and Access Management) – Controls security, permissions, and access. VPC (Virtual Private Cloud) – Your own isolated network inside AWS. RDS (Relational Database Service) – Managed databases like MySQL, PostgreSQL, SQL Server. ...
Read more