DFW CERTIFIED DEVELOPER EXAM
QUESTIONS AND CORRECT ANSWERS!!
AWS SQS long polling allows the SQS service to wait until a message is available in the
queue before sending a response?
true
A visibility timeout is a period of time during which AWS SQS prevents other consuming
components from receiving and processing the message?
true
What AWS service can you use to "fan out" SQS messages to multiple queues?
SNS
(SQS) What is the maximum long poll timeout?
20 seconds
You have a fleet of EC2 instances that are constantly polling empty SQS queues which is
burning CPU complete cycles. What should you do?
Enable SQS long polling
What is the default SQS visibility time out?
30 seconds
EC2 instances download jobs from SQS queue, but are taking too long to process. What api
call can you use to the length of time to process jobs?
ChangeMessageVisibility
(SQS) You are designing a new app which processes payments and delivers promotional
emails to customers. Your need to ensure that the payment process takes priority over the
creation of emails. What is the best way to achieve this?
Use 2 SQS queues. Poll that payment queue first.
,An SQS message can NOT be delivered multiple times?
False, SQS messages can be delivered multiple times
What is the default visibility timeout for SQS?
30 seconds
How long can SQS messages be?
Messages can contain up to 256 KB of text in any format
SQS was the second service on AWS?
False, SQS was the first
DynomaDB writes are measured in 2 KB per write?
False, they are measured in 1 KB per write.
What are the two consistency models used when reading data from DynamoDB?
Eventually Consistent and Strongly consistent
DynamoDB is a NoSQL database by AWS?
True
You have an app that needs 25 items of 13KB per second. Your app uses STRONGLY
consistent reads. What should the throughput be set to? (Math problem)
Calculate read capacity units (items up to 4 KB in size)
Multiply number of items by read capacity units
Do NOT divide by 2 because strongly consistent
Answer: 100
One read capacity unit represents one strongly consistent read per second, or two
eventually consistent reads per second, for items up to 4 KB in size?
True
,When you create a table, you specify how much provisioned throughput capacity you want
to reserve for reads and writes?
True
In DynamoDB, you specify provisioned throughput requirements in terms of capacity
units?
True
One read capacity unit represents one X type of read per second, or two Y type of read per
second?
One strongly consistent read per second. Two eventually consistent reads per second. For items
up to 4 KB in size.
Application needs to read 25 items of 13KB per second. App uses EVENTUALLY
consistent reads. What should you set read throughput to?
Calculate read capacity units (items up to 4 KB in size).
Multiply number of items by read capacity units.
Divide by two because EVENTUALLY consistent.
Answer: 50
A global secondary index contains a selection of attributes from the table, but are
organized by a primary key that is different from the table's? (T/F)
True
DynamoDB local secondary indexes are fixed at 10 per table?
False, local secondary indexes are fixed at 5 per table.
Local secondary indexes give your table a choice of sort keys?
True
What are the three capacity unit sizes in DynamoDB?
, One read capacity unit represents one strongly consistent read per second, for items up to 4 KB
in size.
One read capacity unit represents two eventually consistent reads per second, for items up to 4
KB in size.
One write capacity unit represents one write per second for items up to 1 KB in size.
Using the AWS portal, you are trying to scale DynamoDB past preconfigured maximums.
Which service can be increased through AWS support?
Provisioned throughput limits
What are the steps for calculating write throughput?
Write capacity units are 1 KB per write.
Calculate items per second.
Multiply items per second by writes per item.
You have a motion sensor which writes 600 items of data every minute. Each item is 5 KB.
What should write throughput be?
Calculate items per second.
Multiply items per second by write capacity units per item.
Answer: 50 provisioned write capacity units
What is the api call to receive multiple items from a DynamoDB table?
BatchGetItem
You have a motion sensor which writes 600 items of data every minute. Each item consists
of 5 KB. Your application uses Strongly consistent reads. What should you set read
throughput to?
Calculate items per second.
Calculate read capacity units per item.
Strongly consistent reads are up to 4 KB per read.
Multiply items per second by read capacity units per item.
Answer: 20 provisioned read capacity units
QUESTIONS AND CORRECT ANSWERS!!
AWS SQS long polling allows the SQS service to wait until a message is available in the
queue before sending a response?
true
A visibility timeout is a period of time during which AWS SQS prevents other consuming
components from receiving and processing the message?
true
What AWS service can you use to "fan out" SQS messages to multiple queues?
SNS
(SQS) What is the maximum long poll timeout?
20 seconds
You have a fleet of EC2 instances that are constantly polling empty SQS queues which is
burning CPU complete cycles. What should you do?
Enable SQS long polling
What is the default SQS visibility time out?
30 seconds
EC2 instances download jobs from SQS queue, but are taking too long to process. What api
call can you use to the length of time to process jobs?
ChangeMessageVisibility
(SQS) You are designing a new app which processes payments and delivers promotional
emails to customers. Your need to ensure that the payment process takes priority over the
creation of emails. What is the best way to achieve this?
Use 2 SQS queues. Poll that payment queue first.
,An SQS message can NOT be delivered multiple times?
False, SQS messages can be delivered multiple times
What is the default visibility timeout for SQS?
30 seconds
How long can SQS messages be?
Messages can contain up to 256 KB of text in any format
SQS was the second service on AWS?
False, SQS was the first
DynomaDB writes are measured in 2 KB per write?
False, they are measured in 1 KB per write.
What are the two consistency models used when reading data from DynamoDB?
Eventually Consistent and Strongly consistent
DynamoDB is a NoSQL database by AWS?
True
You have an app that needs 25 items of 13KB per second. Your app uses STRONGLY
consistent reads. What should the throughput be set to? (Math problem)
Calculate read capacity units (items up to 4 KB in size)
Multiply number of items by read capacity units
Do NOT divide by 2 because strongly consistent
Answer: 100
One read capacity unit represents one strongly consistent read per second, or two
eventually consistent reads per second, for items up to 4 KB in size?
True
,When you create a table, you specify how much provisioned throughput capacity you want
to reserve for reads and writes?
True
In DynamoDB, you specify provisioned throughput requirements in terms of capacity
units?
True
One read capacity unit represents one X type of read per second, or two Y type of read per
second?
One strongly consistent read per second. Two eventually consistent reads per second. For items
up to 4 KB in size.
Application needs to read 25 items of 13KB per second. App uses EVENTUALLY
consistent reads. What should you set read throughput to?
Calculate read capacity units (items up to 4 KB in size).
Multiply number of items by read capacity units.
Divide by two because EVENTUALLY consistent.
Answer: 50
A global secondary index contains a selection of attributes from the table, but are
organized by a primary key that is different from the table's? (T/F)
True
DynamoDB local secondary indexes are fixed at 10 per table?
False, local secondary indexes are fixed at 5 per table.
Local secondary indexes give your table a choice of sort keys?
True
What are the three capacity unit sizes in DynamoDB?
, One read capacity unit represents one strongly consistent read per second, for items up to 4 KB
in size.
One read capacity unit represents two eventually consistent reads per second, for items up to 4
KB in size.
One write capacity unit represents one write per second for items up to 1 KB in size.
Using the AWS portal, you are trying to scale DynamoDB past preconfigured maximums.
Which service can be increased through AWS support?
Provisioned throughput limits
What are the steps for calculating write throughput?
Write capacity units are 1 KB per write.
Calculate items per second.
Multiply items per second by writes per item.
You have a motion sensor which writes 600 items of data every minute. Each item is 5 KB.
What should write throughput be?
Calculate items per second.
Multiply items per second by write capacity units per item.
Answer: 50 provisioned write capacity units
What is the api call to receive multiple items from a DynamoDB table?
BatchGetItem
You have a motion sensor which writes 600 items of data every minute. Each item consists
of 5 KB. Your application uses Strongly consistent reads. What should you set read
throughput to?
Calculate items per second.
Calculate read capacity units per item.
Strongly consistent reads are up to 4 KB per read.
Multiply items per second by read capacity units per item.
Answer: 20 provisioned read capacity units
