What is Elastic Load Balancing?
Elastic Load Balancing automatically distributes your incoming traffic across multiple targets, such as EC2 instances, containers, and IP addresses, in one or more Availability Zones. It monitors the health of its registered targets, and routes traffic only to the healthy targets. Elastic Load Balancing Scales your load balancer capacity automatically in response to changes in incoming traffic.
How Elastic Load Balancing works
A load balancer accepts incoming traffic from clients and routes requests to its registered targets (such as EC2 instances) in one or more Availability Zones. The load balancer also monitors the health of its registered targets and ensures that it routes traffic only to healthy targets. When the load balancer detects an unhealthy target, it stops routing traffic to that target. It then resumes routing traffic to that target when it detects that the target is healthy again.
You configure your load balancer to accept incoming traffic by specifying one or more listerners. A listeners. A listener is a process that checks for connection requests. It is configured with a protocol and port number for connections from clients to the load balancer. Likewise, It is configured with a protocol and port number for connections from the load balancer to the targets.
Elastic Load Balancing supports the following types of load balancers:
- Application Load Balancers
- Network Load Balancers
- Gateway Load Balancers
- Classic Load Balancers
There is a key difference in how the load balancer types are configured. With Application Load Balancers, Network Load Balancers, and Gateway Load Balancers, you register targets in target groups, and route traffic to the target groups. With Classic Load Balancers, you register instances with the load balancer.