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AWS 101 > Fundamentals of AWS (Part 2) & RDS, Aurora, Elasticache > Flashcards

Fundamentals of AWS (Part 2) & RDS, Aurora, Elasticache Flashcards

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1
Q

Define Scalability

A

Scalability means that an application / system can handle greater loads by adapting.

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2
Q

What are the two kinds of Scalabilty?

A
  • Vertical Scalability

* Horizontal Scalability (= elasticity)

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3
Q

Define Vertical Scalability?

A

Vertically scalability means increasing the size of the instance

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4
Q

What’s a case where scalability is very common?

A

databases

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5
Q

Name some services that can scale vertically

A

RDS, ElastiCache are services that can scale ver tically.

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6
Q

Define Horizontal Scaling

A

Horizontal Scalability means increasing the number of instances / systems for your application

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7
Q

What’s high availability and what purpose does it serve?

A

High availability means running your application / system in at least 2 data centers (== Availability Zones)
• The goal of high availability is to survive a data center loss

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8
Q

What can you use to horizontal scale: Increase number of instances?

A

Auto Scaling Group

• Load Balancer

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9
Q

What’s an application of High Availability?

A

Run instances for the same application across multi AZ

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10
Q

What are load balancers?

A

Load balancers are servers that forward internet traffic to multiple servers (EC2 Instances) downstream.

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11
Q

Why use a load balancer?

A
  • Spread load across multiple downstream instances
  • Expose a single point of access (DNS) to your application • Seamlessly handle failures of downstream instances
  • Do regular health checks to your instances
  • Provide SSL termination (HTTPS) for your websites
  • Enforce stickiness with cookies
  • High availability across zones
  • Separate public traffic from private traffic
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12
Q

What’s an ELB?

A

EC2 Load Balancer - is a managed load balancer

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13
Q

What are the three types of Load Balancers?

A

Classic Load Balancer (v1 - old generation) - 2009
• Application Load Balancer (v2 - new generation) - 2016
• Network Load Balancer (v2 - new generation) - 2017
• Overall, it is recommended to use the newer / v2 generation load balancers as they provide more features

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14
Q

What are LB Health Checks?

A
  • Health Checks are crucial for Load Balancers
  • They enable the load balancer to know if instances it forwards traffic to are available to reply to requests
  • The health check is done on a port and a route (/health is common)
  • If the response is not 200 (OK), then the instance is unhealthy
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15
Q

What all do Application Load Balancers (ALB) allow you to do?

A

Application load balancers (Layer 7) allow to do:
• Load balancing to multiple HTTP applications across machines (target groups) • Load balancing to multiple applications on the same machine (ex: containers) • Load balancing based on route in URL
• Load balancing based on hostname in URL

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16
Q

What are ALB’s good for?

A

for micro services & container-based application (example: Docker & Amazon ECS)

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17
Q

Stickiness can be enabled at what level?

A

Stickiness can be enabled at the target group level
• Same request goes to the same instance
• Stickiness is directly generated by the ALB (not the application)

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18
Q

Network load balancers (Layer 4) allow to do:

A

Forward TCP traffic to your instances
• Handle millions of request per seconds
• Support for static IP or elastic IP
• Less latency ~100 ms (vs 400 ms for ALB)

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19
Q

ALB can route based on hostname / path?

A

True
• Support routing based on hostname (users.example.com & payments.example.com)
• Support routing based on path (example.com/users & example.com/payments)

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20
Q

ALB is a great fit with ___?

A

ECS (Docker)

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21
Q

Any Load Balancer (CLB, ALB, NLB) has a ____ host name?

A

Static

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22
Q

LB’s Scale instantaneously?

A

False

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23
Q

NLB directly see this___?

A

client IP

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24
Q

_xx errors are client induced errors? 4 or 5?

A

4

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25
Q

_xx errors are application induced errors. 4 or 5?

A

5 - Load Balancer Errors 503 means at capacity or no registered target

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26
Q

Check this if your LB can’t connect to your application.

A

Security Groups

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27
Q

Explain LB stickiness.

A

It is possible to implement stickiness so that the same client is always redirected to the same instance behind a load balancer

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28
Q

What kind of LB’s does stickiness work for?

A

This works for Classic Load Balancers & Application Load Balancers

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29
Q

The “cookie” used for stickiness doesn’t have an expiration date you control?

A

False - You control the expir date

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30
Q

How does ALB support dynamic host port mapping?

A

With ECS

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31
Q

For public facing NLB - must attach this to maintain static IP per AZ

A

Elastic IP

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32
Q

Private facing: will get random private IP based on free ones at time of creation? True of False

A

True

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33
Q

The Lb uses what kind of SSL/TLS certificate?

A

X.509

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34
Q

How do you manage AWS certificates?

A

ACM (AWS Certificate Manager)

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35
Q

What’s an Auto Scaling Group (ASG)?

A

The goal of an Auto Scaling Group (ASG) is to:
• Scale out (add EC2 instances) to match an increased load
• Scale in (remove EC2 instances) to match a decreased load
• Ensure we have a minimum and a maximum number of machines running • Automatically Register new instances to a load balancer

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36
Q

Use ____ as the scaling policy for ASG

A

CloudWatch Alarm

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37
Q

An ASG Launch Configurations includes?

A
  • AMI + InstanceType
  • EC2 User Data
  • EBSVolumes
  • Security Groups
  • SSH Key Pair
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38
Q

____ attached to an ASG will get assigned to EC2 instances??

A

IAM roles

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39
Q

What do you pay for when using an ASG?

A

ASG’s are free. You pay for the underlying resources being launched

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40
Q

Having instances under an ASG means that if they get terminated for whatever reason, the ASG will restart them. T/ F?

A

True

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41
Q

ASG’s will not terminate an instance marked as unhealthy by a LB?

A

False - It was terminate if marked unhealthy

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42
Q

Define ASG Default Termination Policy (simplified version)

A
  1. Find the AZ which has the most number of instances

2. If there are multiple instances in the AZ to choose from, delete the one with the oldest launch configuration

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43
Q

What’s the ASG The cooldown period?

A

Thecooldownperiod helps to ensure that yourAutoScaling group doesn’t launch or terminate additional instances before the previous scaling activity takes effect.

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44
Q

What’s an EBS Volume?

A

• An EC2 machine loses its root volume (main drive) when it is manually terminated.
• Unexpected terminations might happen from time to time (AWS would email you)
• Sometimes, you need a way to store your instance data somewhere
• An EBS (Elastic Block Store) Volume is a network drive you can attach
to your instances while they run
• It allows your instances to persist data

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45
Q

is EBS locked to AZ?

A
  • It’s locked to an Availability Zone (AZ)

* An EBS Volume in us-east-1a cannot be attached to us-east-1b • To move a volume across, you first need to snapshot it

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46
Q

EBS Volumes have provised capacity is what sizes?q

A

GB, and IOPS

47
Q

EBS VOlumes comes in 4 types?

A
  • GP2 (SSD): General purpose SSD volume that balances price and performance for a wide variety of workloads
  • IO1 (SSD): Highest-performance SSD volume for mission-critical low-latency or high- throughput workloads
  • ST1 (HDD): Low cost HDD volume designed for frequently accessed, throughput- intensive workloads
  • SC1 (HDD): Lowest cost HDD volume designed for less frequently accessed workloads
48
Q

Only these types of EBS volumes can be used as boot volumes

A

Only GP2 and IO1 can be used as boot volumes

49
Q

EBS Volumes are characterized in ..?

A

EBS Volumes are characterized in Size | Throughput | IOPS (I/O Ops Per Sec)

50
Q

EBS Volume Types Use cases GP2

A
  • Recommended for most workloads • System boot volumes
  • Virtual desktops
  • Low-latency interactive apps
  • Development and test environments
  • 1 GiB - 16TiB
  • Small gp2 volumes can burst IOPS to 3000
  • Max IOPS is 16,000…
  • 3 IOPS per GB, means at 5,334GB we are at the max IOPS
51
Q

EBS Volume Types Use cases IO1

A
  • Critical business applications that require sustained IOPS performance, or more than 16,000 IOPS per volume (gp2 limit)
  • Large database workloads, such as:
  • MongoDB, Cassandra, Microsoft SQL Server, MySQL, PostgreSQL, Oracle
  • 4 GiB - 16TiB
  • IOPS is provisioned (PIOPS) – MIN 100 - MAX 64,000 (Nitro instances) else
  • The maximum ratio of provisioned IOPS to requested volume size (in GiB) is 50:1
52
Q

EBS Volume Types Use cases ST1

A
  • Streaming workloads requiring consistent, fast throughput at a low price. • Big data, Data warehouses, Log processing
  • Apache Kafka
  • Cannot be a boot volume
  • 500 GiB - 16TiB
  • Max IOPS is 500
  • Max throughput of 500 MiB/s – can burst
53
Q

EBS Volume Types Use cases SC1

A
  • Throughput-oriented storage for large volumes of data that is infrequently accessed
  • Scenarios where the lowest storage cost is important
  • Cannot be a boot volume
  • 500 GiB - 16TiB
  • Max IOPS is 250
  • Max throughput of 250 MiB/s – can burst
54
Q

Can make Image (AMI) from Snapshot?

A

True

55
Q

EBS volumes restored by snapshots need to be?

A

Pre warmed

56
Q

EBS Snapshots can be automated using

A

Amazon Data Lifecycle Manager

57
Q

EBS backups use IO and you shouldn’t run them while your application is handling a lot of traffic

A

True

58
Q

Max EBS snapshots?

A

100k

59
Q

Can’t copy EBS Snapshots across AZ or Region?

A

False

60
Q

How to migrate EBS volume to different AZ?

A
  • Snapshot the volume
  • (optional) Copy the volume to a different region
  • Create a volume from the snapshot in the AZ of your choice
61
Q

How to encrypt an unencrypted EBS volume?

A
  • Create an EBS snapshot of the volume
  • Encrypt the EBS snapshot ( using copy )
  • Create new ebs volume from the snapshot ( the volume will also be encrypted )
  • Now you can attach the encrypted volume to the original instance
62
Q

Instance Store is another type of network drive?

A

False - It’s physically attached

63
Q

What are the pros and cons of Instance Store?

A
  • Pros:
  • Better I/O performance
  • Good for buffer / cache / scratch data / temporary content • Data survives reboots
  • Cons:
  • On stop or termination, the instance store is lost
  • You can’t resize the instance store
  • Backups must be operated by the user
64
Q

What if you want to increase IOPS to say 100 000 IOPS? What if you want to mirror your EBS volumes?

A

You would mount volumes in parallel in RAID settings!

65
Q

Difference btw RAID 0 and RAID 1?

A

RAID 0 (increase performance) - RAID 1 (increased fault tolerance)

66
Q

What’s Elastic File System (EFS)?

A
  • Managed NFS (network file system) that can be mounted on many EC2 • EFS works with EC2 instances in multi-AZ
  • Highly available, scalable, expensive (3x gp2), pay per use
67
Q

Use Cases of EFS?

A

Use cases: content management, web serving, data sharing,Wordpress

68
Q

Uses ____ to control access to EFS

A

Security Groups

69
Q

Only compatible with Windows based AMI?

A

False - Only Linux

70
Q

Root EBS Volumes of instances get terminated by default if the EC2 instance gets terminated. (you can disable that)

A

True

71
Q

EFS can mount only 1 instance?

A

False - can mount 100’s

72
Q

How Many RDS Read replicas for read scalability?

A

Up to 5

73
Q

Read Replicas can be within AZ, Cross AZ, or Cross Region?

A

True

74
Q

Replication for RDS is not ASYNC and is instantly available?

A

False - It Is ASYNC so reads are eventually consistent

75
Q

Replicas can be promoted to their own DB?

A

True

76
Q

Apps must update ____ to leverage read replicas?

A

connection string

77
Q

RDS Multi AZ is what kind of replication? SYNC or ASYNC?

A

SYNC

78
Q

What’s the point of RDS Multi AZ?

A

Not used for scaling
• Increase availability
• Failover in case of loss of AZ, loss of network, instance or storage failure
• No manual intervention in apps

79
Q

RDS Backups are automatically enabled in RDS?

A

True

80
Q

Give some features of Automated Backups.

A
  • Daily full snapshot of the database
  • Capture transaction logs in real time
  • => ability to restore to any point in time
  • 7 days retention (can be increased to 35 days)
81
Q

RDS allows for encryption using?

A

AWS KMS - AES-256 encryption

82
Q

In Flight data encryption using?

A

SSL certificates

83
Q

How do you enforce SSL using PostGreSQL and MySQL?

A

PostgreSQL: rds.force_ssl=1 in the AWS RDS Console (Paratemer Groups)

MySQL: Within the DB:
GRANT USAGE ON . TO ‘mysqluser’@’%’ REQUIRE SSL;

84
Q

How do you connect using SSL to RDS?

A

Provide the SSLTrust certificate (can be download from AWS) Provide SSL options when connecting to database

85
Q

RDS DB’s are usually deployed in a public subnet.

A

FALSE - usually deployed in a private subnet

86
Q

RDS Security works by leveraging ____?

A

Security Groups - it controls who can communicate with RDS

87
Q

IAM Policies help do what for RDS?

A

Who can manage AWS RDS

88
Q

A traditional username and password and IAM users can be used to login to the DB?

A

True

89
Q

What two SQL languages are supported with Aurora?

A

Postgres and MySQL

90
Q

Aurora storage automatically grows in what increments and up to what size?

A

10GB, up to 64TB

91
Q

Aurora can have up to how many replicas what what’s the replica lag?

A

Up to 15 replicas and 10 ms replica lag

92
Q

Failover is Aurora is not instantaneous?

A

False

93
Q

How do you encrypt an unencrypted RDS?

A

unencrypted DB => snapshot => copy snapshot as encrypted => create DB from snapshot

94
Q

RDS automatically enabled encryption at rest?

A

True - Is done only when you first create the DB instance

95
Q

What’s your responsibility with RDS?

A
  • Check the ports / IP / security group inbound rules in DB’s SG
  • In-database user creation and permissions
  • Creating a database with or without public access
  • Ensure parameter groups or DB is configured to only allow SSL connections
96
Q

What’s AWS responsibility for RDS?

A
  • No SSH access
  • No manual DB patching
  • No manual OS patching
  • No way to audit the underlying instance
97
Q

Amazon RDS supports Transparent Data Encryption for DB encryption? What kind of instances allow this?

A

• Oracle or SQL Server DB instance only

98
Q

Transparent Data Encryption (TDE) Can be used on top of KMS for RDS?

A

True - May affect performance

99
Q

IAM Authentication words for what kind of RDS instances?

A

Works for MySQL, PostgreSQL

100
Q

The lifespan of an IAM Auth token for RDS is how long?

A

15-minutes

101
Q

Where are IAM Auth tokens generated?

A

AWS Credentials

102
Q

SSL must be used when connecting to the RDS database?

A

True

103
Q

Easy to use EC2 ____ to connect to the RDS database

A

Instance Roles

104
Q

Aurora Serverless Only supports ___ ?

A

MySQL & Postgres

105
Q

Aurora serverless DB cluster starts, shutsdown and scallers automaticall based on?

A

CPU / Connections

106
Q

You can migerate from aurora cluster to serverless and viceversa?

A

True

107
Q

Aurora Serverless usage is measured in ?

A

ACU (Aurora Capacity Units)

108
Q

How are you billed using aurora serverless?

A

Billed in 5 minutes increment of ACU

109
Q

What is ElastiCache?

A

ElastiCache is to get managed Redis or Memcached

110
Q

How does ElastiCache help DB’s?

A

Helps reduce load off of databases for read intensive workloads

Helps make your application stateless

111
Q

Cache must have an __ __ to make sure only the most current data is used in there.

A

Invalidation Strategy

112
Q

Both Memcache and Redis survive reboots?

A

False - Only Redis

113
Q

Redis supports what kind of security login?

A

Redis Auth (username / Password)

AWS 101 (80 decks)

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