Based on the incoming application traffic, Elastic Load Balancing automatically distributes traffic across EC2 instances. Elastic Load Balancing detects unhealthy instances and moves traffic to healthy instances till the unhealthy instances are restored back.
Elastic Load Balancing is used for
1. Better fault tolerance
2. DNS failover
3. Auto Scaling
4. Easy creation of entry point for VPC (Virtual Private Cloud)
Elastic Load Balancing Features:
1. Incoming traffic can be distributed across amazon Ec2 instances in a single availability zone or multiple zones.
2. Helps creation of security groups when used in a Virtual Private Cloud (VPC)
3. Detects health of Amazon Ec2 instances. For example, when a load balanced instance is detected, Elastic Load Balancing makes sure not to route traffic to that instance.
4. Elastic load balancing supports sticking user sessions to specific EC2 instances.
5. Supports both Internet Protocol v4 and v6 (IPv4 and IPv6)
6. Supports SSL termination
7. Elastic Load balancing metrics, request count and latency, are reported by Amazon CloudWatch
The cost depends on the usage of a Elastic Load Balancer. The charge is on an hourly basis and for each GB transferred through the Elastic Load Balancer. Payment is made on a monthly basis.