ELB & ASG

Question 1

What is Vertical Scalability? What is Horizontal Scalability?

Answer 1

Vertical scalability means increasing the size of the instance. Horizontal scalability means increasing the number of instances / systems for your application.

Question 2

What is an Elastic Load Balancer?

Answer 2

An Elastic Load Balancer (ELB) is a managed load balancer integrated with many AWS services.

Question 3

What enables a load balancer to know if the instances it forwards traffic to are available to respond to requests?

Answer 3

Health checks on a port and route (/health is common). If the response is not 200 (OK), then the instance is unhealthy.

Question 4

What are the 4 managed load balancers supported by AWS?

Answer 4

• Classic Load Balancer (v1 - old generation) (CLB) 2009
• Application Load Balancer (v2 - new generation) (ALB) 2016
• Network Load Balancer (v2 - new generation) (NLB) 2017
• Gateway Load Balancer (GWLB) 2020