AWS Developer Associate Study Deck

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How frequent are the Eventually Consistent Reads within DynamoDB?

A. 5 per second
B. 1 per second
C. 150 per second
D. 2 per second
D. Eventually Consistent Reads (default) consist of 2 reads per second.
How frequent are the Strongly Consistent Reads within DynamoDB?

A. 5 per second
B. 1 per second
C. 150 per second
D. 2 per second
B. Strongly Consistent Reads consist of 1 read per second.
How large is a Unit of Write throughput within DynamoDB?

A. All writes are 1KB
B. All writes are 2KB
C. All writes are variable in size
D. All writes can scale as needed / specified
A. All DynamoDB Unit of Writes are 1KB
How frequently is a Unit of Write applied to a DynamoDB?

A. 5 writes per second
B. 10 writes per second
C. 100 writes per second
D. 1 write per second
D. 1 Unit of Write per second in DynamoDB
What is the formula for determining DynamoDB read throughput values?
(Size of Read rounded to nearest 4KB chunk / 4KB) X number of items per second.

Divide that value by 2 if Eventually Consistent
Divide that value by 1 if Strong Consistency
Write Throughput Scenario
Application needs to write 12 items of 100KB per item each second. What should you se the write throughput to?
12 x 100 KB = 1200 write units
What is the API call used when authenticating users against a Web Identity Provider like Facebook, Google, Amazon, etc.)?
AssumeRoleWithWebIdentity API call while passing the provider's token and specifying the ARN (Amazon Resource Number) for the IAM Role.
What is the default timeout of Temporary Security Credentials issued by AWS after a user has authenticated with a third-party Identity Provider?

A. 30 minutes
B. Unlimited
C. 1 hour
D. 24 hours
C. 1 hour -- minimum is 15 minutes
How does a DynamoDB Conditional Write work?
The update is sent with the anticipated current value. If the current value has changed, an update does not occur.

Conditional Writes are "Indempotent."

Repeats are discarded.
In what order are Atomic Counters written to a DynamoDB?
All write requests are applied in the order in which they are received.
What is the operation that applies an Atomic Counter update to a DynamoDB?
UpdateItem operation can increment or decrement the value of an existing attribute without interfering with other write requests.
Are Atomic Counter updates idempotent?
No. Duplicate Atomic Counter submissions can redundantly update a value in a DynamoDB.

Should only be used for attributes where approximate values are acceptable.
What type of call can be used to retrieve multiple items from a DynamoDB?
BatchGetItem api calls can retrieve up to 1 MB of data, which can contain as many as 100 items.
A DynamoDB BatchGetItem API call is limited to retrieving items from a single table.

True or False
False.

A BatchGetItem request can retrieve items from multiple tables.
What is the promised latency for a DynamoDB instance?
Single-digit millisecond latency AT ANY SCALE.
An administrator can SSH into a DynamoDB host to perform a security update?

True or False
False. DynamoDB is a fully-managed NoSQL database solution. No host-level access is allowed.
What data storage models are supported by DynamoDB?
DynamoDB supports both document and key-value data models.
What is the default read model within a DynamoDB?

A. Strongly Consistent Reads
B. Eventual Consistent Reads
B. Eventually Consistent Reads are the default.

Consistency is usually reached within a second. Repeating a read should return updated data.
Which of the following describes the storage architecture for a DynamoDB instance? (Choose multiple)

A. Spread Across 3 geographically distinct data centers
B. Leverages S3 for data redundancy
C. Utilizes EBS for file system integrity
D. Stored on SSD devices
A & D.

DynamoDB data files are on SSD storage spread across 3 geographically distinct data centers.
What are the 3 schema elements of a DynamoDB instance?
Tables
Items (think a row of data in a table)
Attributes (think a column of data in a table)
What is the simplest Primary Key available for use within DynamoDB?
Single Attribute (think Unique ID)
Partition Key (Hash Key) composed of one attribute
What is the most complex Primary Key available for use within DynamoDB?
Composite (think Unique ID and a Date Range)
Partition Key & Sort Key (Hash & Range) composed of two attributes
How does DynamoDB utilize a Partition Key?
DynamoDB hashes the partition key value and the output determines the partition - physical location in which the data element is stored. No two items in a table can have the same partition key value.
How does DynamoDB implement a Composite Key?
DynamoDB hashes the partition key value and stores the item in a location determined by the hash output. Items with the same partition key are stored together in sorted order by sort key value.

Partition Key is not unique, but Sort Key must be within groupings by Partition Key.
What is a DynamoDB Local Secondary Index?
Same Partition Key, but different sort key
Which of the following are true for a DynamoDB Local Secondary Index? (Choose Multiple)

A. Different Partition Key and Different Sort Key
B. Can be created only when creating a table.
C. Can be created anytime
D. Same Partition Key, Different Sort Key
E. Cannot be modified or removed after created
DynamoDB Local Secondary Index:

B. Can be created only when creating a table.
D. Same Partition Key, Different Sort Key
E. Cannot be modified or removed after created
Which of the following are true for a DynamoDB Global Secondary Index? (Choose Multiple)

A. Different Partition Key and Different Sort Key
B. Can be created only when creating a table.
C. Can be created anytime
D. Same Partition Key, Different Sort Key
E. Cannot be modified or removed after created
DynamoDB Global Secondary Index:

A. Different Partition Key and Different Sort Key
C. Can be created anytime (also deleted)
How long can a DynamoDB store modified data?

A. 30 seconds
B. 1 hour
C. 24 hours
D. 10 minutes
C. 24 hours
How many indexes are allowed per table? (Choose multiple)

A. 5 Global Secondary Indexes
B. 1 Global Secondary Index
C. 1 Local Secondary Index
D. 5 Local Secondary Indexes
A DynamoDB table allows for

A. 5 Global Secondary Indexes
D. 5 Local Secondary Indexes
What is used within a DynamoDB query to retrieve data?
A query operation finds items in a table using only primary key attribute values. You must provide a partition attribute name and a distinct value to search for.
What optional arguments can be provided within a DynamoDB query?
You may optionally provide a sort key attribute name and value and use a comparison operator to refine the search results.
What parameter can be passed with a query to limit the attributes returned by a DynamoDB instance?
A ProjectionExpression parameter can filter the attributes returned by the DynamoDB.
In what order would a DynamoDB instance return the following query sort key results?

131
72
15
302
19
Query results are sorted by the sort key. Numerical sort keys are returned in numeric order:

15
19
72
131
302
In what order would a DynamoDB instance return the following query sort key results?

George
Frank
Elvis
Carlos
Samantha
These would be returned in ASCII character code order-- ascending.
How can DynamoDB result sort order be reversed?
The default is for the results to be returned in ASCENDING order. Setting the ScanIndexForward query parameter to false will set the sort order to DESCENDING.
The ProjectionExpression parameter in a Scan operation can limit the attributes returned for every item from a DynamoDB instance.

True or False
True.

ProjectionExpression parameter limits the attributes, but the Scan will still return all items (rows) in the table.
What protocols are supported by SNS?
Supported push-protocols for SNS include:

HTTP
HTTPS
EMAIL
EMAIL-JSON
Amazon SQS
Application
Messages may be customized for each protocol
What are SWF Workers?
SWF Workers are programs that interact with Amazon SWF to get tasks, process tasks, and return the results.
What is an SWF Decider?
SWF Decider is a program that controls the coordination of tasks, i.e. their ordering, concurrency, and scheduling according to the application logic.
What is an SWF Domain?
Workflow execution and activity types are scoped to a domain. Domains isolate a set of types, executions, and task lists from others within the same account.
What AWS API call can be used to create a new Domain?
The RegisterDomain API call can be used to define a new domain using JSON.
How long may an SWF Workflow be stored in an AWS queue?
Maximum workflow storage is 1 year and is always measured in seconds.
How are CloudFormation templates formatted?
CloudFormation templates are structured in JSON.
What function call can be used to populate the "Output" of a CloudFormation template?
Fn::GetATT can be used to return values such as the DNS name of the load balancer.
What happens to the partially-created resources if a CloudFormation operation encounters an error?
The default is for a rollback to delete the partially-provisioned resources.
What are the preconfigured platform options for ElasticBeanstalk?
IIS
Node.js
PHP
Python
Ruby
Tomcat
GlassFish
Docker
What are all the Relational Database Types available in AWS RDS?
SQL Server
Oracle
MySQL
PostgreSQL
Aurora
MariaDB
What is Data Warehousing?
Used to pull in large and complex data sets and apply business intelligence. Used by management to do queries on data.
What are the two in-memory caching engines available for Elasticache?
Memcached
Redis
Does RDS represent OLTP or OLAP?
Amazon RDS represents OLTP- Online Transaction Processing.

Not OLAP - Online Analytics Processing
What is the minimum and maximum for files stored on S3?
Minimum is 0 byte
Maximum is 5TB
How is an S3 bucket name structured?
https://s3-eu-west-1.amazonaws.com/snake150
What are the requirements for an S3 lifecycle to transition a file to Infrequent Access storage?
Files must be 128Kb or larger and 30 days must have passed since the creation date.
What is a CloudFront Edge Location?
Location where the content will be cached. This is separate to an AWS Region / Availability Zone.
What is a CloudFront Origin?
The origin of the files a CDN will distribute. This can be an S3 Bucket, an EC2 Instance, an Elastic Load Balancer, or Route53.
What is a Cloudfront Distribution?
Name given the CDN which consists of a collection of Edge Locations.
What is a Cloudfront Web Distribution?
Typically used for websites.
What is a CloudFront RTMP distribution?
Used for media streaming.
What is the default for a CloudFront distribution TTL?
The default TTL is 24 hours measured in seconds.
What are two ways to limit access to an S3 bucket?
Bucket policies
Access Control Lists
What are the four methods available for encrypting files at rest within S3?
S3 Managed Keys -- SSE-S3
AWS Key Management Service -- SSE-KMS
Server Side Encryption with customer-provided keys -- SSE-C
Client side encryption prior to upload
What is an S3 Gateway Stored Volume?
Entire dataset is stored onsite and is asynchronously backed up to S3.
What is an S3 Gateway Cached Volume?
Entire dataset is stored on S3 and the most frequently accessed data is cached onsite.
What is an S3 Gateway Virtual Tape Library (VTL)?
Used for backup and integrates with third-party backup apps.
What are the unique considerations of Import / Export Disk?
Imports to EBS, S3, Glacier
Only exports from S3
Elastic Load Balancers are not free.

True or False
True. With an ELB, customer is charged by the hour and on a per-GB basis for usage.
How does an S3 Website URL look?
The website format for S3 is--

http://snake150.s3-website-eu-west-1.amazonaws.com

Which contrasts with S3 bucket URL:

https://s3-eu-west-1.amazonaws.com/snake150-website/index.html
S3 file access may be improved if the beginning of file names are different.

True or False?
True. S3 stores data physically in alphabetical order. Salting the filenames with disorder can spread files throughout S3 storage media.
What is the largest size file you can transfer to S3 with a PUT operation?
5Gb
How can customers upload objects larger than 100mb to an S3 bucket?
Multi-part upload capability
An S3-hosted bucket uses HTTPS protocol in its URL while an S3-hosted website uses HTTP protocol in its URL.

True or False?
True.

The website format for S3 is--

http://snake150.s3-website-eu-west-1.amazonaws.com

Which contrasts with S3 bucket URL:

https://s3-eu-west-1.amazonaws.com/snake150-website/index.html
How many policies can be applied to an IAM Group?

A. Unlimited
B. 25
C. 8
D. 100
E. 10
E. 10

An IAM group may have 10 policies attached to it.
Which of the following VPC considerations are true?

A. Security Groups require inbound and outbound ports to be specified.
B. Security Groups do not require outbound ports to be specified if an inbound port is allowed.
C. Access Control Lists require inbound and outbound ports to be specified.
D. Access Control Lists do not require outbound ports to be specified if an inbound port is allowed.
B & C.

Access Control Lists are Stateless while Security Groups are Stateful.
When creating a new VPC, a subnet is automatically created.

True or False
False. Subnet must be created by the administrator after creating a VPC.
When creating a new VPC, a routing table is automatically created.

True or False
True. A "Main" route table is created automatically in a newly-created VPC.
A default Security Group is created whenever you create a new VPC.

True or False
True.
When creating a new VPC, default Network ACLs are also created automatically.

True or False
True.
What three network configuration objects are created by default with a newly created VPC?
Security Group
Main Routing Table
Network ACLs
How many Access Control Lists may be associated with a subnet within a VPC?

A. Unlimited
B. 5
C. 0
D. 1
D. A subnet can be associated with only one Access Control List.
How many VPC's are allowed in a single region by default?
Five