SAP-C02 Exam - Question 41

Question

A company recently deployed an application on AWS. The application uses Amazon DynamoDB. The company measured the application load and configured the RCUs and WCUs on the DynamoDB table to match the expected peak load. The peak load occurs once a week for a 4-hour period and is double the average load. The application load is close to the average load for the rest of the week. The access pattern includes many more writes to the table than reads of the table.

A solutions architect needs to implement a solution to minimize the cost of the table.

Which solution will meet these requirements?

Examice · Accepted Answer

The most appropriate solution to minimize the cost of the DynamoDB table is to use AWS Application Auto Scaling to increase capacity during the peak period and purchase reserved RCUs and WCUs to match the average load. This approach utilizes reserved capacity for the consistent average load, which is more cost-effective, and leverages auto-scaling to handle the known peak periods, ensuring the table can accommodate higher traffic without incurring the higher costs associated with on-demand capacity.

zhangyu20000 · Answer

A is correct. On demand mode is for unknown load pattern, auto scaling is for know burst pattern

ccort · Answer

A
on-demand prices can be 7 times higher, given the options it is better to have reserved WCU and RCU and auto scale in the given schedule

Simon523 · Answer

Reserved capacity is available for single-Region, provisioned read and write capacity units (RCU and WCU) on DynamoDB tables including global and local secondary indexes. You cannot purchase reserved capacity for replicated WCUs (rWCUs).

ninomfr64 · Answer

A -> You can scale DynamoDB tables and global secondary indexes using target tracking scaling policies and scheduled scaling. In this I would go for scheduled scaling.
https://docs.aws.amazon.com/autoscaling/application/userguide/services-that-can-integrate-dynamodb.html
B -> on-demand capacity mode is for unknown workload, this is not the case
C -> DAX come with costs and it helps with reads, while here we have a more write-bound workload
D -> See B and C comments

anubha.agrahari · Answer

https://aws.amazon.com/blogs/database/amazon-dynamodb-auto-scaling-performance-and-cost-optimization-at-any-scale/#:~:text=You%20can%20approximate%20a%20blend,save%20money%20as%20reserved%20capacity

kz407 · Answer

A is badly worded however, because it says "application" autoscaling. We are not talking about that here. Either it should be reworded as "DynamoDB autoscaling" for the answer to be correct.
On-demand capacity mode is for unknown read/write patterns. Since the load change patterns are known, anything that involves on-demand capacity modes can be eliminated (hence not B).
DAX is a caching service deployed in front of DynamoDB. It is geared towards "performance at scale". Problem in the use case, is to optimize table costs. Using DAX will incur additional costs. Hence anything that involves DAX (C and D) can also be eliminated.

mav3r1ck · Answer

Considering the application's need to handle a peak load that is double the average and the fact that the workload is write-heavy, option B (Configure on-demand capacity mode for the table) is the most suitable solution. It directly addresses the variability in workload without requiring upfront capacity planning or additional management overhead, thus likely providing the best cost optimization for this scenario. On-demand capacity mode eliminates the need to scale resources manually or through Auto Scaling and ensures that you only pay for the write and read throughput you consume.

awsent · Answer

Correct Answer: A
Application auto scaling can be used for scheduled scaling for DynamoDB tables and GSIs
https://docs.aws.amazon.com/autoscaling/application/userguide/what-is-application-auto-scaling.html

whenthan · Answer

https://aws.amazon.com/blogs/database/amazon-dynamodb-auto-scaling-performance-and-cost-optimization-at-any-scale/#:~:text=You%20can%20approximate%20a%20blend,save%20money%20as%20reserved%20capacity.

severlight · Answer

we use scheduled scaling here

jpa8300 · Answer

I choose option D, because DAX is not only an accelerator for the Reads, it also cache releasing a lot of load from the DB.

igor12ghsj577 · Answer

I think there is mistake in answer A, and it should be DynamoDb auto scaling instead of application autos calling. Or application and dynamoDB auto scaling.

8608f25 · Answer

Option B is the most cost-effective solution for workloads with significant fluctuations and unpredictable access patterns. The on-demand capacity mode automatically adjusts the table’s throughput capacity as needed in response to actual traffic, eliminating the need to manually configure or manage capacity. This mode is ideal for applications with irregular traffic patterns, such as a significant peak once a week, because you only pay for the read and write requests your application performs, without having to provision throughput in advance. Option B directly addresses the requirement to minimize costs associated with fluctuating loads, especially when the load significantly exceeds the average only during a brief period, by leveraging DynamoDB’s on-demand capacity mode to automatically scale and pay only for what is used.

Kubernetes · Answer

A is correct. The focus is minimizing the cost of tables.

Malcnorth59 · Answer

AWS documentation suggests A is correct:
https://docs.aws.amazon.com/autoscaling/application/userguide/what-is-application-auto-scaling.html

zolthar_z · Answer

Auto-scaling is for known traffic pattern, On-demand is for unknown traffic patter and also could be more expensive

vn_hunglv · Answer

Tôi chọn A

SAP-C02 Exam - Question 41

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