ELB

Question 1

What is ELB?

Answer 1

Distribute traffic to multiple targets across multiple AZ’s

Question 2

How does Health Checks work with ELB?

Answer 2

ELB will check and route only to healthy targets

Question 3

What layer does ALB operate on?

Answer 3

Layer 7

Question 4

What is ALB used for?

Answer 4

Servicing HTTP/HTTPS requests and intelligent path routing

Question 5

What does a Listener consist of?

Answer 5

A protocol and a port,

Rules with conditionals and actions and priority

Question 6

How do you handle a scenario where you need to send certain url paths to a different region? What LB type should you use?

Answer 6

Use Path Based Patterns, Use a ALB to route

Question 7

*What protocols does ALB support?

Answer 7

Only HTTP and HTTPS

Question 8

What do you need to use a HTTPS Listener? How does it work?

Answer 8

You need an SSL server certificate on the LB, so that the LB will terminate the incoming and decrypt the client req before sending to targets

Question 9

What is a Listener?

Answer 9

Checks for client connections on a protocol and port

Question 10

What is a target group?

Answer 10

Routes requests to 1 or more targets in the group based on protocol and port

Question 11

What is the use case for a NLB?

Answer 11

You need extreme performance, low latency, with thousands of concurrent connections for TCP

Question 12

What layer does NLB operate on?

Answer 12

layer 4

Question 13

Can you do intelligent based routing with a NLB?

Answer 13

No you cannot, there are no Rules on Listeners

Question 14

How do you use TLS with NLB?

Answer 14

You need a TLS Listener that will encrypt/decrypt the traffic on the NLB and have the SSL Certificate on the LB

Question 15

What is a CLB? Why use it?

Answer 15

Legacy LB that lets you balance HTTP/HTTPS or TCP. Enables use of x-forward-header and sticky sessions.

Question 16

What is x-forward-header ?

Answer 16

A Layer 7 feature that lets you pass the client ip address to targets behind the LB

Question 17

Can you configure Rules for a CLB?

Answer 17

No you can’t use Rules for a CLB

Question 18

What is Connection Draining or Deregistration Delay?

Answer 18

When instances become unhealthy or deregistered but there is a connection from a LB. This allows inflight requests to be completed by keeping existing connections open if this happens.

Question 19

What is cross zone balancing?

Answer 19

Sends requests evenly to all targets in all AZ’s in the target group. Instead of splitting to each ELB in each AZ, then distributing to targets only within that AZ in which the ELB is in.

Question 20

*What is the difference between a ALB and CLB sticky session?

Answer 20

CLB is at an instance level while ALB is at a target group level

Question 21

What should you do given a scenario where you remove an EC2 instance from the pool but now the user is getting an error?

Answer 21

This means that sticky session was enabled, so you have to disable sticky sessions

Question 22

What features does ALB have for intelligent routing?

Answer 22

1. Path based
2. Host based
3. Query parameters and strings
4. Headers
5. HTTP Verbs