MLS-C01 Data Engineering Practice Question
A data engineer is building a data pipeline that uses Amazon S3 to store raw data, AWS Lambda for transformation, and Amazon DynamoDB for serving. The Lambda function experiences high latency when writing to DynamoDB. Which action will most effectively reduce the latency?
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
✓
Increase the DynamoDB write capacity units
Increasing write capacity units for DynamoDB directly reduces write latency by minimizing throttling. DAX (Option A) is a read cache and does not improve write latency. Option B is incorrect because using S3 would increase latency due to its different access pattern. Option C is incorrect because VPC gateway endpoint improves network connectivity but does not reduce write latency.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Enable DynamoDB Accelerator (DAX) for caching
Why it's wrong here
DAX is a read cache and does not reduce write latency, so this is not the most effective action.
- ✗
Use Amazon S3 instead of DynamoDB
Why it's wrong here
Using S3 instead of DynamoDB would change storage paradigm and typically increase latency for low-latency writes.
- ✗
Configure a VPC gateway endpoint for DynamoDB
Why it's wrong here
A VPC gateway endpoint improves network connectivity but does not directly reduce write latency.
- ✓
Increase the DynamoDB write capacity units
Why this is correct
Increasing write capacity units directly addresses throttling and reduces write latency by providing more throughput.
Quick reference
AWS S3 Storage Class Comparison
| Storage Class | Min Duration | Retrieval | Use Case |
|---|---|---|---|
| S3 Standard | None | Immediate | Frequently accessed data |
| S3 Standard-IA | 30 days | Immediate | Infrequent access, rapid retrieval |
| S3 One Zone-IA | 30 days | Immediate | Non-critical infrequent data |
| S3 Intelligent-Tiering | None | Immediate–hours | Unknown or changing access patterns |
| S3 Glacier Instant | 90 days | Milliseconds | Archive with instant retrieval |
| S3 Glacier Flexible | 90 days | Minutes–hours | Archive, flexible retrieval |
| S3 Glacier Deep Archive | 180 days | Hours | Long-term compliance archive |
Go deeper
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This MLS-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 MLS-C01 exam.