Answer: Choose provisioned mode. Update the read and write capacity units appropriately.

## Explanation **Correct Answer: B - Choose provisioned mode. Update the read and write capacity units appropriately.** **Why this is correct:** 1. **Usage Pattern Analysis:** The application runs tests for only 4 hours once a week. This is a highly predictable, intermittent workload with long periods of inactivity. 2. **Provisioned Mode Benefits:** - **Cost Optimization:** With provisioned mode, you pay for the capacity you provision regardless of usage. Since the company knows exactly how many read/write operations are needed during the 4-hour test window, they can provision exactly that capacity. - **No Unused Capacity Costs:** During the remaining 164 hours of the week when no tests are running, the provisioned capacity costs are minimal compared to on-demand pricing. - **Predictable Billing:** The company can accurately forecast costs based on their known test requirements. 3. **On-Demand Mode Drawbacks:** - On-demand mode charges per request, which would be more expensive for predictable, high-throughput workloads. - Since the company knows their exact throughput requirements, they don't need the flexibility of on-demand scaling. 4. **Reserved Capacity Drawbacks:** - Reserved capacity requires a commitment (1 or 3 years) and upfront payment. - This is not cost-effective for a workload that only runs 4 hours per week. - The company doesn't have other DynamoDB use cases, so the reserved capacity would be wasted most of the time. **Key Considerations:** - The company can use **Auto Scaling** with provisioned mode to automatically adjust capacity during the test window if needed. - They can schedule capacity changes using AWS Lambda or CloudWatch Events to increase capacity just before tests and decrease it afterward. - Since they know the exact throughput requirements, they can provision the minimum necessary capacity. **Cost Comparison:** - **Provisioned Mode:** Pay for 4 hours of provisioned capacity per week - **On-Demand Mode:** Pay for actual requests during 4 hours, which would be higher for predictable high-throughput workloads - **Reserved Capacity:** Pay upfront for capacity that would be unused 97% of the time This solution provides the best cost optimization for this specific, predictable, intermittent workload pattern.

Author: LeetQuiz Editorial Team