AWS Elastic Load Balancer Overview

An AWS Elastic Load Balancer (Amazon ELB) is a service that helps to distribute the incoming traffic or incoming application traffic across the amazon EC2 instances, IP addresses and other services like Amazon Lambda. Amazon ELB overcomes the instant web application load by distributing the incoming requests into multiples web servers. Amazon ELB service offers three types of Elastic Load Balancers that comes with the features of high availability, automatic scaling, and robust security necessary to make your applications fault-tolerant. The three elastic load balancer are listed below:

  1. Application Load Balancer
  2. Network Load Balancer
  3. Classic Load Balancer

Application Load Balancer:

An Application Load balancer is used to route the request of HTTP and HTTPS to the application or modern application architecture like microservices and containers. Application Load Balancer route the traffic to microservices or containers within Virtual Private Cloud (Amazon VPC).

Network Load balancer:

The network load balancer is used to route the traffic of Transmission Control Protocol (TCP) and Transport Layer Security (TLS) to Amazon EC2 instances, microservices, and containers. Application Load Balancer route the traffic to target within Virtual Private Cloud (Amazon VPC).

Classic Load Balancer:

Classic Load Balancer is used to route the incoming traffic of protocols TCP, SSL/TLS, HTTP, HTTPS across multiple Amazon EC2 machines in a single availability zone or multiple availability zones. Classic Load Balancing never distributes the load on unhealthy instances reported by “Health Check” but distributes to the rest of healthy Amazon EC2 Instances.

Health Check

Health Check continuously sends signals within a user-defined interval of time to specific instances to check that an Amazon EC2 instance is healthy or not. If health check receives the response within the metric values, then the instance is healthy but if we do not get the response within the defined metrics that means the instance is not healthy. After this response, the Load Balancer only routes the traffic to healthy Amazon EC2 instances.


Elastic Load Balancing provides integrated certificate management and SSL/TLS decryption, allowing you the flexibility to centrally manage the SSL settings of the load balancer and offload CPU intensive work from your application. Amazon Load Balancer works with Amazon Virtual Private Cloud (VPC) to provide robust security features.