Elastic Load Balancing automatically “balances” incoming application traffic “loads” across multiple “targets” so that no one resource becomes over burdened.  The targets can be EC2 instances, containers, and IP addresses, and can handle varying loads of application traffic in a single or multiple Availability Zones.

By distributing incoming traffic to multiple targets, Elastic Load Balancing provides fault tolerance by ensuring scalability, performance, and security.

Types of Elastic Load Balancers

Classic Load Balancer

Classic Load Balancer distributes traffic across multiple EC2 instances, operating in both request and connection level.  It is meant for applications built within the EC2-Classic network.  It passes requests along in a Round-Robin format.

Application Load Balancer

Application Load Balancer balances HTTP and HTTPS traffic, providing advanced request routing.  It routes traffic to targets within Virtual Private Cloud (VPC) based on the request content.

Network Load Balancer

Network Load Balancer is best for distributing TCP traffic, and is optimized to handle sudden and volatile traffic patterns.  It maintains ultra-low latencies while handling millions of requests per second, routing traffic to targets within VPC.

Resources

• Elastic Load Balancing (AWS)