HA And Scaling

Question 1

What is an Elastic Load Balancer (ELB)?

Answer 1

It is a DNS record that points at 1+ nodes per A Z

Question 2

What is the difference between an internet facing node and an internal node?

Answer 2

internet facing has public IP, internal only has private

Question 3

Can a private EC2 instance be used with a load balancer?

Answer 3

Yes, because the EC2 instance doesn’t have to accept a public connection, just one coming from load balancer.

Question 4

What types of protocols is ALB used for?

Answer 4

HTTP/HTTPS.

Question 5

What can you use to forward traffic to different target groups depending on IP address, or redirect requests?

Answer 5

ALB rules.

Question 6

What protocols should you use NLB for?

Answer 6

TCP, TLS, UDP…more or less just “non-http/s”.

Question 7

What has faster latency: ALB or NLB?

Answer 7

NLB.

Question 8

What are Launch Configurations and Launch Templates used for?

Answer 8

Define config of an EC2 instance in advance

Question 9

Which can be edited after creation: Launch Templates or Launch Configuration?

Answer 9

Neither, but launch templates support versioning

Question 10

What is the main use of an auto scaling group (ASG)?

Answer 10

Automatic scaling and self-healing for EC2.

Question 11

Where is an ASG configured?

Answer 11

Within a VPC.

Question 12

What is configured within the ASG, so ASG knows where to launch instances?

Answer 12

Subnets from the VPC that the ASG is attached to.

Question 13

What are the 3 parameters that determine how many instances will be running at once within a subnet attached to an ASG?

Answer 13

Min, max, and desired size

Question 14

What are the three types of scaling policies?

Answer 14

Manual, Scheduled, and Dynamic

Question 15

In dynamic scaling, what is the difference between simple and stepped scaling?

Answer 15

Simple is more “binary” e.g. CPU > 50% or <50%. Stepped defines what happens at certain thresholds. E.g. >50% launch 1, >70% launch 2, etc.

Question 16

YOU WILL

Answer 16

EAT THE BUGS

Question 17

What is the cooldown period?

Answer 17

How long to wait after performing a scaling action before performing another.

Question 18

Launch Template will define ____ is launched, while ASG defines ____ and ____

Answer 18

what, when, where

Question 19

True or False: ASGs NEED scaling policies

Answer 19

False

Question 20

In ASG, what can you use to backup data when an instance is terminated, or load data on an instance before it is launched?

Answer 20

Lifecycle Hooks

Question 21

In ASG, what occurs when an instance fails health checks?

Answer 21

It is replaced.

Question 22

What is a grace period, and why might you use it?

Answer 22

Defines a set of time after instance is launched before starting to perform a health check. You might use it if you want to do additional configuration on an instance before checking.

Question 23

In load balancing, what is Bridging?

Answer 23

When the load balancer listener is configured for HTTPS, and SSL is passed through to backend instances. Instances need certificates!

Question 24

In load balancing, what is Pass-through?

Answer 24

Only occurs with NLB. No SSL cert needed on load balancer, but needed on backend instances.

Question 25

In load balancing, what is offload?

Answer 25

Listener configured for HTTPS, but backend connections use HTTP. No certs needed.

Question 26

What is the name of the cookie generated with connection stickiness enabled?

Answer 26

AWSALB

Question 27

What is the main advantage of using connection stickiness?

Answer 27

Connections maintain sessions even when connecting to different instances.

Question 28

What is the main use of a gateway load balancer?

Answer 28

A GWLB helps run and scale 3rd party security appliances like firewalls, intrusion detection, and prevention systems.