Elastic Load Balancing provides round robin web call distribution across a set of identical web instances. In addition to ease of administration it keeps an eye on the health of instances in the pool and auto routes traffic around any problem instances that show up.

Here is the summary from Amazon.

Elastic Load Balancing – Elastic Load Balancing automatically distributes incoming application traffic across multiple Amazon EC2 instances. It enables you to achieve even greater fault tolerance in your applications, seamlessly providing the amount of load balancing capacity needed in response to incoming application traffic. Elastic Load Balancing detects unhealthy instances within a pool and automatically reroutes traffic to healthy instances until the unhealthy instances have been restored. You can enable Elastic Load Balancing within a single Availability Zone or across multiple zones for even more consistent application performance. Amazon CloudWatch can be used to capture a specific Elastic Load Balancer’s operational metrics, such as request count and request latency, at no additional cost beyond Elastic Load Balancing fees.

Fees: $0.025 per hour for each Elastic Load Balancer, plus $0.008 per GB of data transferred through an Elastic Load Balancer.

Elastic Load Balancing Commands

Command Name —–> Description

• elb-configure-healthcheck —–> Configure the parameters for checking the health of instances registered with a LoadBalancer
• elb-create-lb —–> Create a new LoadBalancer
• elb-delete-lb —–> Deletes an existing LoadBalancer
• elb-deregister-instances-from-lb —–> Deregisters Instances from a LoadBalancer
• elb-describe-instance-health —–> Describes the state of Instances
• elb-describe-lbs —–> Describes the state and properties of LoadBalancers
• elb-disable-zones-for-lb —–> Remove Availability Zones from an LoadBalancer
• elb-enable-zones-for-lb —–> Add Availability Zones to existing LoadBalancer
• elb-register-instances-with-lb —–> Registers Instances to a LoadBalancer

Use –help in conjunction with any of the preceding commands for more information and usage examples.