Distributing web traffic with Amazon ELB

When you have more than one EC2 instance that works as part of a fleet hosting a given application, you need a mechanism in place to distribute traffic to those instances in a manner that spreads the load across the fleet. At a very basic level, this is what Amazon ELBs are designed to do. Amazon ELBs distribute traffic across multiple targets, which can be EC2 instances, containers, Internet Protocol (IP) addresses, and even Lambda functions. They can handle varying traffic for your application, evenly distributing the load across those registered targets either in a single AZ or across multiple AZs within a given Region. This also means that ELBs can assist in designing architecture that offers HA and fault tolerance, as well as working with services such as Auto Scaling to deliver automatic scalability features to your applications. Note, however, that ELBs are regional-based only, so you cannot use an ELB to distribute traffic across Regions...