DEA-C01 Data Store Management Practice Question
A data engineer is designing a data store for a real-time analytics application that requires sub-millisecond read and write latency. The data is accessed via a REST API. Which AWS services should the engineer consider? (Choose THREE.)
⚠ Common exam trap
The trap here is that candidates may overlook DAX as a separate service and assume DynamoDB alone provides sub-millisecond latency, but DynamoDB's base latency is typically 1-10 milliseconds for strongly consistent reads, and DAX is required to achieve sub-millisecond performance for read-heavy workloads.
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
✓
Amazon ElastiCache for Redis
Amazon ElastiCache for Redis is correct because it provides an in-memory data store that delivers sub-millisecond read and write latency, ideal for real-time analytics. Redis supports data structures like strings, hashes, and sorted sets, and can be accessed via REST API through a caching layer or directly with Redis commands. This makes it suitable for low-latency, high-throughput workloads where disk-based storage would introduce unacceptable delays.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Amazon S3
Why it's wrong here
S3 has higher latency (tens of milliseconds).
- ✗
Amazon RDS for MySQL
Why it's wrong here
RDS typically has higher latency and is not designed for sub-millisecond access.
- ✓
Amazon ElastiCache for Redis
Why this is correct
Redis provides sub-millisecond latency.
- ✓
Amazon DynamoDB
Why this is correct
DynamoDB provides single-digit millisecond latency.
- ✓
DynamoDB Accelerator (DAX)
Why this is correct
DAX provides sub-millisecond caching for DynamoDB.
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
Related to this question
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Same concept, more angles
1 more way this is tested on DEA-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 data engineer is designing a data store for a real-time analytics application that requires sub-millisecond read and write latency. The data is key-value in nature and the workload is both read-heavy and write-heavy. Which AWS service is most suitable?
easy- A.Amazon ElastiCache for Redis
- ✓ B.Amazon DynamoDB
- C.Amazon RDS for MySQL
- D.Amazon S3
Why B: Amazon DynamoDB is the most suitable service because it is a fully managed NoSQL key-value and document database designed for single-digit millisecond latency at any scale, and with features like DynamoDB Accelerator (DAX) it can achieve sub-millisecond read latency. It supports both read-heavy and write-heavy workloads through its distributed architecture and auto-scaling capabilities, making it ideal for real-time analytics applications.
JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This DEA-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 DEA-C01 exam.