AWS Elastic Load Balancing Concepts
External
Internal
Overview
Load Balancer
A load balancer serves as the single point of contact for clients. The load balancer distributes incoming traffic across multiple targets, which actually know how to handle requests and provide responses. This increases the availability of the application. A load balancer can have one or more listeners.
Target
Listener
Load Balancer Types
Used by Amazon ECS.
Application Load Balancer
Allows containers to use dynamic host port mapping (multiple tasks allowed per container instance). Multiple services can use the same listener port on a single load balancer with rule-based routing and paths.
Network Load Balancer
A Network Load Balancer functions at the fourth layer of the Open Systems Interconnection (OSI) model. After the load balancer receives a request, it selects a target from the target group for the default rule using a flow hash routing algorithm.