DBS-C01 Monitoring and Troubleshooting Practice Question
A company notices that its Amazon DynamoDB table is consuming more read capacity than expected. The table has a global secondary index (GSI) with a different sort key. Which action would most likely reduce the read consumption?
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
✓
Enable DAX (DynamoDB Accelerator) to cache read results.
Enabling DynamoDB Accelerator (DAX) caches read results from the DynamoDB table, reducing the number of reads that consume read capacity units (RCUs). When the table has a GSI, reads that use the GSI also consume RCUs from the index. DAX can cache both base table and index reads, thereby lowering overall read consumption. Option A is incorrect because increasing write capacity does not affect read consumption. Option C is incorrect because changing the sort key does not directly reduce read capacity usage. Option D is incorrect because a local secondary index (LSI) uses the same partition key and does not help reduce read consumption from a GSI.
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 write capacity of the table.
Why it's wrong here
Write capacity does not affect read consumption.
- ✓
Enable DAX (DynamoDB Accelerator) to cache read results.
Why this is correct
DAX reduces the number of reads to the table, lowering read capacity consumption.
- ✗
Change the sort key of the base table to match the GSI sort key.
Why it's wrong here
Changing the sort key would require re-engineering and may not reduce read consumption.
- ✗
Create a local secondary index (LSI) with the same sort key as the GSI.
Why it's wrong here
LSIs share capacity with the base table and would not reduce read consumption.
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Same concept, more angles
1 more way this is tested on DBS-C01
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. 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?
medium- A.Increase the provisioned write capacity to 2000 WCUs to handle bursts.
- B.Schedule the Scan to run during off-peak hours when sensor writes are lower.
- C.Enable DAX (DynamoDB Accelerator) to cache Scan results and reduce read consumption on the table.
- ✓ D.Switch the table to on-demand capacity mode to eliminate throttling.
Why D: 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.
JA
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.