Elastic Load Balancing provides fault tolerance for your applications by automatically balancing traffic across targets – Amazon EC2 instances, containers and IP addresses – and Availability Zones while ensuring only healthy targets receive traffic. If all of your targets in a single Availability Zone are unhealthy, Elastic Load Balancing will route traffic to healthy instances in other Availability Zones. Once targets have returned to a healthy state, load balancing will automatically resume to the original targets.

With enhanced container support for Elastic Load Balancing, you can now load balance across multiple ports on the same Amazon EC2 instance. You can also take advantage of deep integration with the Amazon EC2 Container Service (ECS), which provides a fully-managed container offering. Simply register a service with a load balancer, and ECS transparently manages the registration and de-registration of Docker containers. The load balancer automatically detects the port and dynamically reconfigures itself.

Elastic Load Balancing provides confidence that your applications will scale to the demands of your customers. With the ability to trigger Auto Scaling for your Amazon EC2 instance fleet when latency of any one of your EC2 instances exceeds a preconfigured threshold, your applications will always be ready to serve the next customer request.

Elastic Load Balancing makes it easy to create an internet-facing entry point into your VPC or to route request traffic between tiers of your application within your VPC. You can assign security groups to your load balancer to control which ports are open to a list of allowed sources. Because Elastic Load Balancing is integrated with your VPC, all of your existing Network Access Control Lists (ACLs) and Routing Tables continue to provide additional network controls.

When you create a load balancer in your VPC, you can specify whether the load balancer is internet-facing (default) or internal. If you select internal, you do not need to have an internet gateway to reach the load balancer, and the private IP addresses of the load balancer will be used in the load balancer’s DNS record.

Elastic Load Balancing offers ability to load balance across AWS and on-premises resources using the same load balancer. For example, if you need to distribute application traffic across both AWS and on-premises resources, you can achieve this by registering all the resources to the same target group and associating the target group with a load balancer. Alternatively, you can use DNS-based weighted load balancing across AWS and on-premises resources using two load balancers, with one load balancer for AWS and other for on-premises resources.

You can also use hybrid load balancing to benefit separate applications where one is in a VPC and the other is in an on-premises location. Simply put the VPC targets in one target group and the on-premises targets in another target group, and then use content based routing to route traffic to each target group.