High Availability & Scalability

Question 1

What are the 4 types of Load Balancer available?

Answer 1

• CLB Classic Load Balancers
• ALB Application Load Balancers
• NLB Network Load Balancers
• GWLB Gateway Load Balancers

Question 2

What 3 protocols does the Classic Load Balancer support?

Answer 2

• TCP Layer 4

- HTTP and HTTP Layer 7

Question 3

What 2 protocols are the Classic Load Balancer Health Checks on?

Answer 3

• TCP

- HTTP

Question 4

What protocol does the Application Load Balancer support?

Answer 4

HTTP Layer 7

Question 5

What are the 4 routing options in the ALB?

Answer 5

• URL path
• URL hostname
• Query String
• Headers

Question 6

With CLB and ALB, we get a fixed hostname, what does that look like?

Answer 6

xxx.region.elb.amazonaws.com

Question 7

How do we retrieve the client ip, port and proto if using an ELB?

Answer 7

IP - X-Forwarded-For
Port - X-Forwarded-Port
Proto - X-Forwarded-Proto

Question 8

What protocol does the Network Load Balancer support?

Answer 8

Layer 4 to allow TCP & UDP

Question 9

Does the NLB have a fixed hostname?

Answer 9

No, it has a static IP per AZ

Question 10

What is a Gateway Load Balancer used for?

Answer 10

To deploy, scale and manage a fleet of 3rd party network virtual appliances in AWS

Question 11

What protocol does the Gateway Load Balancer support?

Answer 11

Layer 3 Network Layer for IP Packets

Question 12

In AWS console, what protocol and port does the Gateway Load Balancer use?

Answer 12

GENEVE on port 6081

Question 13

What are sticky sessions?

Answer 13

Its when the same client traffic is always redirected to the same instance behind the ELB

Question 14

What are sticky sessions also known as?

Answer 14

Session Affinity

Question 15

What is needed for sticky sessions?

Answer 15

A cookie which has an expiration date

Question 16

What ELB is Cross Zone Load Balancing enabled on?

Answer 16

The ALB has it enabled by default and cannot be disabled so there is no charge

Question 17

What ELBs is Cross Zone Load Balancing disabled on?

Answer 17

• NLB has it disabled by default and charges apply if enabled.
• CLB has it disabled by default and there are no charges if enabled

Question 18

What does SSL stand for?

Answer 18

Secure Sockets Layer

Question 19

What does TSL stand for?

Answer 19

Transport Layer Security

Question 20

What kind of certificates does the ELB use?

Answer 20

X.509 certificate (SSL/TLS certificate)

Question 21

What does SNI stand for?

Answer 21

Server Name Indication

Question 22

What does SNI do?

Answer 22

It solves the problem of loading multiple certs onto one web server

Question 23

What is Connection Draining?

Answer 23

It provides time to complete in-flight requests while terminating and prevents new requests being sent

Question 24

What is Connection Draining also known as?

Answer 24

Deregistration Delay

Question 25

What are 4 metrics to scale on in an Auto Scaling Group?

Answer 25

• CPU Utilization
• RequestCountPerTarget
• Average Network In/Out
• Any Custom Metric

Question 26

What is the default cooldown period for ASGs?

Answer 26

300 seconds (5 minutes)

Question 27

What are the 2 steps taken in the default termination policy?

Answer 27

• Find the AZ which has the most instances

- Delete the instance with the oldest launch configuration