Elastic Load Balancing & Auto Scaling

Question 1

What is ELB?

Answer 1

Elastic Load Balancer: Distributes incoming application traffic evenly across multiple EC2 instances in multiple availability zones.

Question 2

What are the primary benefits of using ELB?

Answer 2

1. Increased availability by distributing traffic evenly across EC2 instances, thus preventing one instance from being overloaded.
2. Increased fault tolerance of your application because ELB detects unhealthy instances and routes traffic only to healthy instances.

Question 3

What is auto-scaling?

Answer 3

A feature that allows you to make sure you have the correct number of EC2 instances available to handle the load for your application.

Question 4

What is an auto-scaling group?

Answer 4

A collection of EC2 instances.

You can specify the minimum and maximum number of EC2 instances in each auto-scaling group and teh auto-scaling feature will ensure those thresholds are never exceeded.

Question 5

What is a scaling policy?

Answer 5

A policy that can be configured within the auto-scaling feature that allows you to look for certain events and take scaling action accordingly.

i.e. if CPU utilization exceeds 80%, add 1 EC2 instance or if CPU utilization is less than 30%, remove 1 EC2 instance.