Configuring Load Balancer for a Web Application

Introduction

Modern web applications must handle thousands of requests every second. A single server cannot manage such load without delays or failures. This is where a load balancer becomes vital.

A load balancer spreads incoming requests across multiple servers. This improves performance, reliability, and uptime. If one server goes down, traffic is shifted to healthy ones. Users continue accessing the app without disruption.

This case study explains how we configured an AWS Application Load Balancer (ALB) to optimize traffic distribution for a client’s web application.

Problem

The client had a growing web application hosted on AWS. With rising traffic, a single server setup caused:

Slow response times during peak hours.

Frequent downtime when servers crashed.

No failover plan, leading to service outages.

The challenge was clear. We had to configure a load balancer that could:

Distribute traffic evenly.

Detect server health automatically.

Keep applications online during failures.

Scale with future demand.

Solution

We deployed an AWS Application Load Balancer. The setup included target groups, listener rules, and health checks to keep traffic flow smooth.

Step 1: Configure a Target Group

A target group defines where the load balancer should send traffic. Each server or function is added here.

In the AWS EC2 console, we created a new target group.

Selected target type: EC2 instances, IP addresses, or Lambda functions.

Named the group and set protocols and ports.

Chose IP type: IPv4 or IPv6.

Configured health checks with success codes, timeouts, and thresholds.

These checks ensure only healthy targets receive requests.

Step 2: Register Targets

We then registered the actual servers with the target group.

For EC2, we added instances with ports.

For IP, we entered private addresses from the client’s VPC.

For Lambda, we attached function ARNs.

With targets in place, the load balancer could send requests to multiple servers.

Step 3: Configure Load Balancer and Listener

Next, we created the Application Load Balancer.

Chose Application Load Balancer in AWS.

Named the balancer and set it as Internet-facing.

Selected IPv4 for compatibility.

Mapped it to subnets across two availability zones.

Assigned a security group to control traffic.

Added listeners:

HTTP port 80 for general use.

HTTPS port 443 with SSL for secure traffic.

Listeners act like gatekeepers, routing requests to the right target group.

Step 4: Test the Load Balancer

Testing confirmed the setup worked.

Checked target group health status.

Copied the load balancer’s DNS name.

Accessed it through a browser.

Verified responses came from healthy servers.

Shut down one server to test failover.

The load balancer instantly shifted traffic to available servers, proving reliability.

Results

After configuring the AWS load balancer, the client saw major improvements.

Metric	Before	After
Uptime	95%	99.90%
Response Time	800ms	250 – 300 ms
Downtime	Full Outages	Automatic Failover
Concurrent Users	~50	Hundreds+

The application could now handle more users, with faster response and near-zero downtime.

Conclusion

Configuring an AWS Application Load Balancer is essential for any business running critical web applications. It ensures:

High availability by routing traffic to healthy servers.

Scalability as user traffic grows.

Fault tolerance during outages.

Improved performance with reduced response times.

For our client, this setup transformed their application from unstable to reliable. With the load balancer, they now serve users efficiently and confidently, even during peak traffic.