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Exam AWS Certified Solutions Architect - Professional SAP-C02 All Questions

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Exam AWS Certified Solutions Architect - Professional SAP-C02 topic 1 question 41 discussion

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?

  • A. Use AWS Application Auto Scaling to increase capacity during the peak period. Purchase reserved RCUs and WCUs to match the average load.
  • B. Configure on-demand capacity mode for the table.
  • C. Configure DynamoDB Accelerator (DAX) in front of the table. Reduce the provisioned read capacity to match the new peak load on the table.
  • D. Configure DynamoDB Accelerator (DAX) in front of the table. Configure on-demand capacity mode for the table.
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Suggested Answer: A 🗳️

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zhangyu20000
Highly Voted 1 year, 10 months ago
A is correct. On demand mode is for unknown load pattern, auto scaling is for know burst pattern
upvoted 25 times
AimarLeo
9 months, 3 weeks ago
But the pattern here is known.. 4 hours peak time etc.. not sure if that would be the write answer
upvoted 1 times
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dqwsmwwvtgxwkvgcvc
1 year, 3 months ago
How AWS Application Auto Scaling scale the read/write performance of DynamoDB?
upvoted 1 times
tannh
1 year, 2 months ago
You can scale DynamoDB tables and global secondary indexes using target tracking scaling policies and scheduled scaling. https://docs.aws.amazon.com/autoscaling/application/userguide/services-that-can-integrate-dynamodb.html
upvoted 1 times
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ccort
Highly Voted 1 year, 10 months ago
Selected Answer: A
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
upvoted 16 times
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Sin_Dan
Most Recent 1 month ago
Selected Answer: B
B is the right answer. Reserved RCU/WCU locks you into fixed cost. Even though on demand is more expensive, the additional cost is paid only for 4 hrs a week.
upvoted 1 times
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amministrazione
2 months, 3 weeks ago
A. Use AWS Application Auto Scaling to increase capacity during the peak period. Purchase reserved RCUs and WCUs to match the average load.
upvoted 1 times
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subbupro
2 months, 4 weeks ago
I think B is correct. because reserved is not required, ondemand would be better because it requireds only 4 hours per week. so B would be better. Autoscaling of the application can not impact dynamo db tables.
upvoted 1 times
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vn_hunglv
4 months ago
Selected Answer: A
Tôi chọn A
upvoted 1 times
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zolthar_z
4 months ago
Selected Answer: A
Auto-scaling is for known traffic pattern, On-demand is for unknown traffic patter and also could be more expensive
upvoted 2 times
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Malcnorth59
6 months ago
Selected Answer: A
AWS documentation suggests A is correct: https://docs.aws.amazon.com/autoscaling/application/userguide/what-is-application-auto-scaling.html
upvoted 3 times
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Kubernetes
6 months, 3 weeks ago
A is correct. The focus is minimizing the cost of tables.
upvoted 1 times
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mav3r1ck
8 months ago
Selected Answer: B
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.
upvoted 2 times
mav3r1ck
8 months ago
A. AWS Application Auto Scaling with Reserved Capacity Pros: Auto Scaling allows you to automatically adjust the provisioned throughput to meet demand, and purchasing reserved RCUs and WCUs can reduce costs for the capacity you know you'll consistently use. Cons: This option might not be as cost-effective for workloads with significant variability and a high write-to-read ratio, especially if the peak load is much higher than the average load. Reserved capacity benefits consistent usage patterns, but the peak load being double the average may not be fully optimized here.
upvoted 1 times
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mav3r1ck
8 months ago
B. On-demand Capacity Mode Pros: On-demand capacity mode is ideal for unpredictable workloads because it automatically scales to accommodate the load without provisioning. You pay for what you use without managing capacity planning. This mode is particularly suitable for the described scenario where the load spikes significantly and unpredictably. Cons: While potentially more expensive per unit than provisioned capacity with auto-scaling, it eliminates the risk of over-provisioning or under-provisioning.
upvoted 1 times
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kz407
8 months, 1 week ago
Selected Answer: A
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.
upvoted 2 times
Malcnorth59
6 months ago
I initially thought the same but the AWS definition of Application autoscaling listed here includes DynamoDB: https://docs.aws.amazon.com/autoscaling/application/userguide/what-is-application-auto-scaling.html
upvoted 1 times
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anubha.agrahari
8 months, 2 weeks ago
Selected Answer: A
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
upvoted 2 times
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8608f25
9 months, 2 weeks ago
Selected Answer: B
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.
upvoted 1 times
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igor12ghsj577
9 months, 3 weeks ago
Selected Answer: A
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.
upvoted 1 times
igor12ghsj577
9 months, 3 weeks ago
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. When the workload decreases, Application Auto Scaling decreases the throughput so that you don't pay for unused provisioned capacity.
upvoted 2 times
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jpa8300
10 months, 3 weeks ago
Selected Answer: D
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.
upvoted 1 times
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ninomfr64
11 months ago
Selected Answer: A
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
upvoted 2 times
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severlight
1 year ago
Selected Answer: A
we use scheduled scaling here
upvoted 1 times
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