How Load Balancer Work with Animation | System Design Interview Basics

Introduction

This tutorial explains how load balancers work, their importance in managing traffic for web applications, and how they improve system performance and reliability. Load balancers ensure that incoming traffic is efficiently distributed among multiple servers, preventing any single server from becoming overwhelmed. This guide will help you understand the core functions of load balancers and how they operate in various scenarios.

Step 1: Understanding the Role of a Load Balancer

• A load balancer acts as a "traffic cop" for your servers.
• Its primary function is to distribute incoming network traffic across multiple backend servers.
• This distribution helps:
  • Maximize speed and capacity utilization.
  • Prevent server overload, which can degrade performance.
  • Ensure high availability of applications by rerouting traffic if a server goes down.

Step 2: How Load Balancers Handle Traffic

• Load balancers manage client requests through several strategies:
  • Round Robin: Distributes requests sequentially to each server.
  • Least Connections: Sends requests to the server with the fewest active connections.
  • IP Hashing: Routes requests based on the client's IP address.
• These strategies ensure efficient traffic management tailored to your specific needs.

Step 3: Automatic Server Management

• When a server in the group becomes unresponsive or goes down, the load balancer automatically redirects traffic to other online servers.
• Conversely, when a new server is added to the pool, the load balancer starts directing traffic to it without manual intervention.

Step 4: Starting at the DNS Level

• Load balancing often begins at the Domain Name System (DNS) level.
• The DNS can be configured to distribute requests to various servers based on predefined rules, enhancing redundancy and performance.

Step 5: Real-World Applications

• Load balancers are essential in scenarios such as:
  • High-traffic websites (e.g., e-commerce platforms).
  • Applications requiring high availability (e.g., online banking).
  • Services that need to scale dynamically (e.g., cloud-based applications).

Conclusion

Load balancers are crucial for maintaining the performance and availability of web applications, especially as traffic increases. By understanding how load balancers operate and their various strategies for traffic management, you can ensure that your applications are robust and responsive. As a next step, consider exploring load balancer implementation in cloud environments like AWS or Azure, which offer managed load balancing services.