HA Architecture

Question 1

What is a Load Balancer

Answer 1

Physical/Virtual device designed to help you balance the network load across multiple webservers

Question 2

3 types of Load Balancers

Answer 2

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

Question 3

Application Load Balancers

Answer 3

1. best suited for load balancing of HTTP and HTTPS traffic.
2. Operate at Layer 7 and are application aware
3. Intelligent and you can create advanced request routing, sending specified requests to specific web server

Question 4

Network Load Balancers

Answer 4

1. Best suited for load balancing of TCP traffic where extreme performance is required
2. Operating at the connection level (Layer4)
3. Capable of handling millions of requests per second while maintaining ultra low latencies

Question 5

Classic Load Balancers

Answer 5

1. Legacy elastic load balancers
2. HTTP/HTTPS applications and use layer 7 specific features such as X forwarded and sticky sessions
3. You can also use strict Layer 4 Load balancing for applications that rely purely on the TCP protocol

Question 6

Error 504 for Classic Load Balancer means

Answer 6

application is having issues - either at the Web Server layer or at the DB layer

Question 7

X-Forwarded-For-Header

Answer 7

way to get the IP4 address of the end user

Question 8

Instances monitored by ELB are reported as

Answer 8

InService or OutofService

Question 9

How are health checks done

Answer 9

checks the instance health by talking to it

Question 10

Load Balancers are given an IP address instead of a DNS name - True or False

Answer 10

False; LBs have their own DNS name

Question 11

Launch configuration

Answer 11

an instance configuration template that an Auto Scaling group uses to launch EC2 instances

Question 12

You can specify your launch configuration with multiple Auto scaling groups - true or false

Answer 12

true

Question 13

How many launch configurations can you specify for an auto scaling group at a time?

Answer 13

1

Question 14

Can you modify a launch configuration after you’ve created it?

Answer 14

No

Question 15

When you create an Auto Scaling group using an EC2 instance, Amazon EC2 Auto Scaling automatically creates a launch configuration for you and associates it with the Auto Scaling group - true or false

Answer 15

true

Question 16

Sticky session

Answer 16

allows you to bind a user’s session to a specific Ec2 instance. This ensures that all requests from the user during the session are sent to the same instance.

Question 17

Sticky sessions can also be enabled for Application Load Balancers but the traffic will be sent to

Answer 17

Target Group Level

Question 18

If you notice that there are no traffic going to the second EC2 instance, then what will you have to do

Answer 18

Disable sticky sessions

Question 19

If you have EC2 instances that are writing to a local disc, then you will have to

Answer 19

Enable stick session

Question 20

Cross Zone Load Balancing

Answer 20

enables you to load balance across multiple AZs

Question 21

Path Based Routing/Path Patterns

Answer 21

allows you to direct traffic to different EC2 instances based on the URL contained in the request

Question 22

Example of Path Based routing

Answer 22

You can route general requests to one target group and requests to render images to another target group

Question 23

When you design the architecture, always design for

Answer 23

failure

Question 24

When designing an HA, use multiple AZs and multiple regions wherever you can - true or false

Answer 24

true

Question 25

Multi-AZ is mostly used for

Answer 25

Disaster Recovery

Question 26

Read Replicas mostly for

Answer 26

RDS

Question 27

What is scaling out

Answer 27

where we use ASG to add Ec2 instances

Question 28

Scaling up means

Answer 28

increase resources inside our Ec2 instance

Question 29

ELBs vs Route 53

Answer 29

1. ELBs are intended to load balance across EC2 instances in a single region whereas Route 53 is intended to help balance traffic across Regions 2. Route53 only changes the address that your clients' requests resolve to but ELB actually reroutes traffic.

Question 30

Elastic Beanstalk

Answer 30

aimed for developers who have no idea about AWS but just wants to deploy their code right away

Question 31

Is there a charge for Elastic Beanstalk?

Answer 31

No, you only have to pay for the AWS resources needed to store and run your applications

Question 32

Stacks

Answer 32

A stack is a collection of AWS resources that you can manage as a single unit. In other words, you can create, update, or delete a collection of resources by creating, updating, or deleting stacks.

Question 33

CloudFormation

Answer 33

way of completely scripting your cloud envrionment

Question 34

AWS CloudFormation ensures all stack resources are created or deleted as appropriate- true or false

Answer 34

true

Question 35

Quick Start

Answer 35

bunch of CloudFormation templates already built by AWS solution architects allowing you to create complex environments very quickly