Elastic Load Balancing & Auto Scaling Groups

Question 1

What does scalability mean?

Answer 1

An application / system can handle greater loads by adapting

Question 2

What are the 2 kinds of sclability?

Answer 2

1. Vertical Scalability

2. Horizontal Scalability (= elasticity)

Question 3

Is scalability the same as high availability?

Answer 3

No, but they are linked

Question 4

What is vertical scalability?

Answer 4

Means increasing / decreasing the size of the instance. There is usually a limit.

Question 5

What is horizontal scalability?

Answer 5

Means increasing / decreasing the number of instances / systems for your application. Implies distributed systems and is very common for web applications

Question 6

What is high availability?

Answer 6

Means running your application / system in at least 2 AZs.

Question 7

What is the goal of high availability?

Answer 7

To survive a data center loss (disaster)

Question 8

High availability goes hand in hand with what type of scaling?

Answer 8

Horizontal

Question 9

Scalability vs Elasticity?

Answer 9

Scalability: ability to accommodate a larger load by making the hardware stronger (scale up), or by adding nodes (scale out)

Elasticity: once a system is scalable, elasticity means that there will be some ‘auto-scaling’ so that the system can scale based on the load. This is ‘cloud-friendly’: pay-per-use, match demand, optimize costs

Question 10

What is agility?

Answer 10

Means new IT resources are only a click away, which means that you reduce the time to make those resources available to your developers from weeks to just minutes

Question 11

Is agility related to scalability?

Answer 11

No

Question 12

What is load balancers?

Answer 12

Servers that forward internet traffic to multiple servers (EC2 instances) downstream

Question 13

Why use a load balancer?

Answer 13

1. Spread load across multiple downstream instances
2. Expose a single point of access (DNS) to your application
3. Seamlessly handle failures of downstream instances
4. Do regular health checks on your instances
5. Provide SSL termination (HTTPS) for your websites
6. High availability across zones

Question 14

Why use an Elastic load balancer?

Answer 14

It is a managed load balancer.

1. AWS guarantees that it will be working
2. AWS takes care of upgrades, maintenance, high availability
3. AWS provides only a few configuration knobs

Question 15

Why not create your own load balancer instead of using one from AWS?

Answer 15

It costs less to setup your own load balancer but it will be a lot more effort on your end (maintenance, integrations)

Question 16

What are the 3 kinds of load balancers offered by AWS?

Answer 16

1. Application Load Balancer (HTTP / HTTPS only) - Layer 7
2. Network Load Balancer (ultra-high performance, allows for TCP) - Layer 4
3. Classic Load Balancer (slowly retiring) - Layer 4 & 7

Question 17

Should you ever choose a classic load balancer?

Answer 17

No, it’s slowly retiring

Question 18

What is an Auto Scaling Group?

Answer 18

Allows you to create and get rid of servers very quickly

Question 19

What are the goals of an auto scaling group?

Answer 19

1. Scale out (add EC2 Instances) to match an increased load
2. Scale in (remove EC2 Instances) to match a decreased load
3. Ensure we have a minimum and maximum number of machines running
4. Automatically register new instances to a load balancer
5. Replace unhealthy instances

Question 20

What are the cost savings associated with auto scaling groups?

Answer 20

Only run at an optimal capacity (principle of the cloud)

Question 21

What is minimum size of Auto Scaling Group

Answer 21

1

Question 22

What is actual size / desired capacity for auto scaling group?

Answer 22

How many EC2 instances you want always running

Question 23

What is the main purpose of High Availability in the Cloud?

1. Increase scalability
2. Application thriving even in case of a disaster
3. Access on computers and smartphones
4. Handle greater loads by launching EC2 instances based on demand

Answer 23

Application thriving even in case of a disaster

Question 24

Which AWS offered Load Balancer should you use to handle hundreds of thousands of connections with low latency?

1. Application Load Balancer
2. Network Load Balancer
3. Elastic Load Balancer

Answer 24

Network Load Balancer

Question 25

Changing an EC2 Instance Type from a t3a.medium to a t3a.2xlarge is an example of?

1. Horizontal scaling
2. High Availability
3. Agility
4. Vertical scaling

Answer 25

Vertical scaling

Question 26

What can you use to handle quickly and automatically the changing load on your websites and applications by adding compute resources?

1. An Elastic Load Balancer
2. A bigger instance type
3. An Auto Scaling Group
4. Health Checks on your EC2 Instances

Answer 26

An Auto Scaling Group

Question 27

Which of the following statements is INCORRECT regarding Auto Scaling Groups?

1. Replace unhealthy instances
2. Are cost-effective by running at optimal capacity
3. Automatically register new instances to a load balancer
4. Automatically changing the EC2 Instance Type

Answer 27

Automatically changing the EC2 Instance Type

Question 28

Which Load Balancer is best suited for HTTP/HTTPS load balancing traffic?

1. Network Load Balancer
2. Classic Load Balancer
3. Elastic Load Balancer
4. Application Load Balancer

Answer 28

Application Load Balancer

Question 29

Which AWS service offers easy horizontal scaling of compute capacity?

1. EBS
2. AMI
3. IAM
4. ASG

Answer 29

ASG

Question 30

Which of the following statements is NOT a feature of Load Balancers?

1. Do regular health checks to your instances
2. Spread load across multiple downstream instanes
3. Handle failures of downstream instances
4. Back-end autoscaling

Answer 30

Back-end autoscaling