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Elastic Load Balancer

Load Balancer and Auto Scaling group work hand in hand

Elastic Load Balancing is the AWS service that automatically distributes incoming application traffic across multiple resources, such as Amazon EC2 instances.

A load balancer acts as a single point of contact for all incoming web traffic to your Auto Scaling group. This means that as you add or remove Amazon EC2 instances in response to the amount of incoming traffic, these requests route to the load balancer first. Then, the requests spread across multiple resources that will handle them. For example, if you have multiple Amazon EC2 instances, Elastic Load Balancing distributes the workload across the multiple instances so that no single instance has to carry the bulk of it.

Classic LB

Classic load balancers support both IPv4 and IPv6. They support HTTP/1 and HTTP/1.1, but only application load balancers support HTTP/2. Further, you must register individual instances, rather than target groups, with classic load balancers; registering target groups is a functionality only available with application load balancers.

An ELB is an elastic load balancer and generally refers to a classic load balancer. An ALB is an application load balancer.

Classic load balancers operate at both the connection (Level 4) and the request (Level 7) layer of the TCP stack.

Application LB

An ALB offers SSL termination and makes the SSL offload process very simple through tight integration with SSL processes. While an ELB will handle SSL termination, it does not offer the management features that ALBs do.

Network LB

Network Load Balancer

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