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Exam AWS Certified Solutions Architect - Associate topic 1 question 161 discussion

A web application running on Amazon EC2 instances writes data synchronously to an Amazon DynamoDB table configured for 60 write capacity units. During normal operation the application writes 50 KB/s to the tale, but can scale up to 500 KB/ s during peak hours. The application is currently throttling errors from the
DynamoDB table during peak hours.
What is the MOST cost-efficient change to support the increased traffic with minimal changes to the application?

  • A. Use Amazon SQS to manage the write operations to the DynamoDB table.
  • B. Change DynamoDB table configuration to 600 write capacity units.
  • C. Increase the number of Amazon EC2 instances to support the traffic.
  • D. Configure Amazon DynamoDB Auto Scaling to handle the extra demand.
Show Suggested Answer Hide Answer

Suggested Answer: D

Comments

JustATechie
8 months, 1 week ago
https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/AutoScaling.html
upvoted 8 times
JustATechie
8 months, 1 week ago
it's correct answer
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jfire
5 months ago
Link indicates D is correct
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tbtln
6 months ago
I THINK A MOST cost-efficient A
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Pupina
6 months ago
I think A is wrong because says sync writing. Ans is D
upvoted 1 times
czhao
1 month, 3 weeks ago
And minimal changes to the application, SQS will involve in some code change
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newbie2019
4 months, 2 weeks ago
I had this question in my exam and I believe to be unfair with people taking the assessment. How do we know that changing DynamoDB table config to 600 write units would not fit? Only because they mentioned no changed to the application correct? But this would be a change in the DB table, not the app. "For example, suppose that you create a table with 10 write capacity units. This allows you to perform 10 writes per second, for items up to 1 KB in size per second" Meaning 600 write unites would fit, plus the LIMIT per table of that is 40k write request units. https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/Limits.html#default-limits-throughput-capacity-modes In the REAL WORLD, the solution would be to change the configuration of DynamoDB. Auto Scaling would suite for the demand in time and this is what they want us to pick in the answer.
upvoted 7 times
AWS_HY
4 months ago
is it D then?
upvoted 3 times
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Rama
3 months, 2 weeks ago
Autoscaling makes more sense , as it reduces itself during non peak hours saving you cost. And cost effectiveness is the keyword there
upvoted 1 times
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somaforever
2 months, 3 weeks ago
D. Configure Amazon DynamoDB Auto Scaling to handle the extra demand. the key here is: "throttling errors from the DynamoDB table during peak hours" according to AWS documentation: * "Amazon DynamoDB auto scaling uses the AWS Application Auto Scaling service to dynamically adjust provisioned throughput capacity on your behalf, in response to actual traffic patterns. This enables a table or a global secondary index to increase its provisioned read and write capacity to handle sudden increases in traffic, without throttling. " https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/AutoScaling.html * "If your application reads or writes larger items (up to the DynamoDB maximum item size of 400 KB), it will consume more capacity units." https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/HowItWorks.ReadWriteCapacityMode.html
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AnNguyen
1 month, 4 weeks ago
"During normal operation the application writes 50 KB/s to the tale, but can scale up to 500 KB/ s during peak hours" For cost-effective, Autoscaling is better than change to 600 write units
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Ejay
1 month, 2 weeks ago
D my take.
upvoted 3 times
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rmehra
1 month, 2 weeks ago
Why A cannot be correct , after all it will decouple the architecture .Reduce the latency as it will have a visibility timeout during which the message will not be sent again . Long polling will also increase the response time . This can very well prevent throttle . From cost perspective also , is SQS not economical than increasing WCU or using ASG to increase the Dynamo Db nodes?
upvoted 1 times
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ByeWorld
1 month, 1 week ago
Requirements: MOST cost-efficient change to support the increased traffic with minimal changes to the application A. Use Amazon SQS to manage the write operations to the DynamoDB table * Need to change application to publish message to SQS. Also need to pool SQS for messages. B. Change DynamoDB table configuration to 600 write capacity units * Not cost-effective since during normal operation application only needs 50 KB/s C. Increase the number of Amazon EC2 instances to support the traffic. * Does not help DynamoDb performance D. Configure Amazon DynamoDB Auto Scaling to handle the extra demand. * Cost effective: only scale up when needed * No change to application So answer is D.
upvoted 8 times
puchongkia
1 month, 1 week ago
detail answer
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stevenmato
3 weeks, 1 day ago
agreed with this !
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awsnoob
1 week, 2 days ago
Can somebody tell me how the heck you use ASG in Dynamo DB?? https://aws.amazon.com/about-aws/whats-new/2019/06/rds-storage-auto-scaling/ 1 RU = 4 KB/s, 600 RU can meet the requirement without much changes to the app and architecture, hence D
upvoted 1 times
awsnoob
1 week, 2 days ago
Sorry my ans is B... Typo
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JQS
5 days, 2 hours ago
A is incorrect as SQS doesn't increase performance on the DB but it ensures that during high load on the DB there are no writes on the DB lost. This will still provide a slow response rate as the problem with the performance on the DB during high demand is still present. I believe that D is the answer as AWS strongly advertises that dynamo DB autoscaling is the best DB to auto adjust according to the demand without you needing to do anything from your end.
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Tush
1 day, 10 hours ago
Answer is D.
upvoted 1 times
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