DBS-C01 Monitoring and Troubleshooting Practice Question
A company uses Amazon DynamoDB to store sensor data from IoT devices. The table has a partition key of DeviceID (String) and a sort key of Timestamp (Number). The table is configured with provisioned capacity of 1000 read capacity units (RCUs) and 500 write capacity units (WCUs). Auto Scaling is enabled with target utilization of 70% and is working correctly. Recently, a new batch job was introduced that performs Scan operations on the entire table every hour. The Scan consumes many read capacity units and causes throttling of the sensor write requests. The team wants to minimize the impact on the write-heavy sensor ingestion. Which approach is BEST?
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Switch the table to on-demand capacity mode to eliminate throttling.
Switching to on-demand capacity mode eliminates throttling by automatically scaling read/write capacity to meet traffic demands. Since the scan operation runs hourly and consumes significant RCUs, on-demand mode will handle the burst without throttling write requests. Option C is incorrect because DAX caches individual items, not entire scan results; hourly scans would cause cache misses, providing no benefit. Option A is incorrect because increasing write capacity does not address read throttling. Option B is incorrect because off-peak scheduling may not be feasible and does not guarantee elimination of throttling.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Increase the provisioned write capacity to 2000 WCUs to handle bursts.
Why it's wrong here
Increasing write capacity only addresses write throttling, not read throttling caused by scans. It also increases costs without solving the problem.
- ✗
Schedule the Scan to run during off-peak hours when sensor writes are lower.
Why it's wrong here
Scheduling scans off-peak may reduce concurrent load but does not guarantee elimination of throttling if sensor writes still occur at high rates during that time.
- ✗
Enable DAX (DynamoDB Accelerator) to cache Scan results and reduce read consumption on the table.
Why it's wrong here
DAX is not effective for full table scans that run infrequently (e.g., hourly) because the cache will not have the data, resulting in cache misses and no reduction in read consumption on the table.
- ✓
Switch the table to on-demand capacity mode to eliminate throttling.
Why this is correct
On-demand capacity mode automatically scales to handle any traffic burst, eliminating throttling for both reads and writes. It is the best choice to prevent scan-induced throttling of write requests.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This DBS-C01 practice question is part of Courseiva's free Amazon Web Services certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the DBS-C01 exam.