HA architecture

Question 1

name the 3 types of load balancers

Answer 1

network, app, classic

Question 2

_____ load balancers are best suited for load balancing of HTTP adn HTTPS traggic. they operate at layer 7 and are app aware. they are intelligent, and you cna create advanced request routing, sending specified requests to specific web servers.

Answer 2

application

Question 3

____ are best suited
for the load balancing of TCP traffic
where extreme performance is required.

Answer 3

Network

Question 4

Network load balancers operate at layer ___4

Answer 4

4

Question 5

these load balancers are capable of handling millions of requests per second, while maintaining ultra-low latencies.

used for extreme performance

Answer 5

network

Question 6

____ load balancers are the legacy elastic balanders. you can load balance http/https apps and use layer 7 specific features, such as x-forwarded and sticky sessions. you can also use strict layer 4 load balancing for apps that rely purely on the TCP protocol.

Answer 6

classic

Question 7

with classic load balancers, If your application stops responding,
the ELB is going to respond with a ___ error.

This means that the app is having issues. this could be either at the web server layer or the db layer. identify where the app is failing, and scale it upor out where possible.

Answer 7

504

Question 8

what does x-forwarded for header do?

Answer 8

shows the user’s public IP address

Question 9

instances monitored by ELB are reported as :

what 2 things?

Answer 9

inservice or outofservice

Question 10

t or false

you get an ip and a dns name for your LB

Answer 10

false, you only get dns name. no IP

Question 11

Classic Load Balancer’s routes each request
independently to the registered EC2 instance
with the smallest load
and what ___ ____ allows you to do
is to bind a user’s session to a specific EC2 instance.
So, you’re gonna stick a user session
to a particular EC2 instance and this ensures
that all requests from the user during the session
are sent to the same instance.

Answer 11

sticky sessions

Question 12

you can also enable sticky sessions
for Application Load Balancers as well,
but this time, the traffic will be sent
at the___ ____ level rather than
at the individual EC2 instance.

Answer 12

target group

Question 13

So, a common exam scenario will be
you’ve got a user, they’re using Route 53,
100% of the traffic’s being sent to a load balancer
in us-east-1a and that load balancer is sending that traffic
on to its four instances which are
in the same Availability Zone as it,
and then you log in to us-east-1b
and you notice that this EC2 instance
is not getting any traffic at all.
What should you do?
Well, you should enable _____ load balancing
and that way, it will get traffic
because it’s in another Availability Zone
and you haven’t enabled ____ load balancing.

Answer 13

cross-zone

Question 14

you can create a listener with rules
to forward requests based on the URL path
and this is known as _____ routing.
So, if you are running microservices,
you can route traffic to multiple back-end services
using ____ routing.

For example, you can route general requests
to one target group and requests to render images
to another target group.

Answer 14

path-based

Question 15

what are the three components of auto scaling?

Answer 15

groups, configuration templates, and different scaling options

Question 16

what is an AUto scaling group

Answer 16

a logical component. ie: web server group, app group, db group, etc.

Question 17

what are config templates concerning auto scaling?

Answer 17

groups uses a lunch template of launch config as a config template for its ec2 instances. you can specify info such as the AMI id, instance type, key pair, SG, and block device mapping for you instances

Question 18

what are scaling options in regards to auto scaling?

Answer 18

scaling optioned provides several ways for you to scale your auto scaling groups. for example, you can configure a group to scale based on teh occurance of specified conditions(dynamic scaling) or on a schedule

Question 19

what are the 5 different scaling options?

Answer 19

There’s maintain the current instance levels at all times.
There’s scale manually.
There’s scale based on a schedule.
There’s scale based on demand.
And then there’s using predictive scaling

Question 20

what is predictive scaling?

Answer 20

scales based on previous performance

Question 21

So you might get some exam questions talking about
highly available architecture, so you might have a website
that requires a minimum of six instances
and it must be highly available.
And you must also be able to tolerate the failure
of one availability zone.
So you are always gonna need six instances
and you can tolerate one availability zone.
So what is the ideal architecture for this environment
while being the most cost effective?

Answer 21

we’re always going to need
three availability zones with three instances
to meet this requirement.
We’re gonna need nine instances total.
That way if we lose one AZ we still got six instances
that will be able to look after our environment.

Question 22

Read Replicas is for disaster recovery

t or f

Answer 22

f

Read Replicas is for performance.

Question 23

what is the difference between scaling up and scaling out?

Answer 23

So scaling out is where we use Auto Scaling group
and we add additional EC2 instances.
Scaling up is where we increase the resources
inside our EC2 instances,
so we might go from a T2 micro to a 6X extra large
or something like that.

Question 24

which s3 buckets are not HA?

Answer 24

1 zone IA

and reduced redundancy

Question 25

what is quick start?

Answer 25

a bunch of cloudformation templates already built by SAs allowing you to create complex environments very quickly.

Question 26

In discussions about Cloud services the words ‘Availability’, ‘Durability’, ‘Reliability’ and ‘Resiliency’ are often used. Which term is used to refer to the likelihood that a resource ability to recover from damage or disruption?

Answer 26

resiliancy

Question 27

In discussions about Cloud services the words ‘Availability’, ‘Durability’, ‘Reliability’ and ‘Resiliency’ are often used. Which term is used to refer to the likelihood that a resource will continue to exist until you decide to remove it?

Answer 27

durability

Question 28

In discussions about Cloud services the words ‘Availability’, ‘Durability’, ‘Reliability’ and ‘Resiliency’ are often used. Which term is used to refer to the likelihood that a resource will work as designed?

Answer 28

reliability