Question 619 of 1,663
DBS-C01 Monitoring and Troubleshooting Practice Question
A company runs a production Amazon DynamoDB table with on-demand capacity. The table stores session data for a web application. Recently, users have reported occasional slow response times. The operations team notices that the table's ConsumedWriteCapacityUnits metric shows occasional spikes that exceed the provisioned throughput (though on-demand auto-scales), and ThrottledWriteEvents metrics show occasional throttling. The application uses the AWS SDK with default retry logic. The database specialist is asked to investigate. Upon reviewing the table configuration, the specialist finds that the table has a simple primary key (partition key only) and the data access pattern is heavily skewed toward a small number of partition keys. The application writes in batches of 25 items using the BatchWriteItem API. What should the specialist recommend to reduce throttling and improve performance?
⚠ Common exam trap
Watch out — candidates often assume on-demand capacity mode eliminates all throttling, but it only manages total table throughput, not per-partition limits, so hot keys still cause throttling.
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
✓
Implement write sharding by adding a random suffix to the partition key to distribute writes more evenly.
The throttling is caused by a hot partition: the table uses a single partition key, and writes are heavily skewed toward a few keys. By adding a random suffix to the partition key (write sharding), the writes are distributed evenly across all partitions, eliminating hot spots and reducing throttling. The on-demand capacity mode already handles overall throughput, but it cannot prevent throttling on individual partitions when access is skewed.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Implement write sharding by adding a random suffix to the partition key to distribute writes more evenly.
Why this is correct
Write sharding spreads writes across multiple partitions, reducing throttling.
- ✗
Increase the provisioned read capacity units to handle the load.
Why it's wrong here
Throttling is on writes, not reads; increasing read capacity does not help.
- ✗
Switch the table to provisioned capacity mode and increase write capacity.
Why it's wrong here
On-demand already auto-scales; the issue is hot partitions, not overall capacity.
- ✗
Enable DynamoDB Accelerator (DAX) to cache write operations.
Why it's wrong here
DAX caches reads, not writes; it does not reduce write throttling.
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Last reviewed: Jun 11, 2026
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.
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