This DEA-C01 practice question tests your understanding of data store management. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
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?
Amazon ElastiCache for Redis
Why wrong: ElastiCache is a cache, not a durable data store; data loss can occur.
Amazon DynamoDB
DynamoDB offers consistent single-digit millisecond latency at scale.
Amazon RDS for MySQL
Why wrong: RDS latency is higher, especially under heavy write loads.
Amazon S3
Why wrong: S3 latency is in the hundreds of milliseconds, not sub-millisecond.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
Amazon DynamoDB
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.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
Amazon ElastiCache for Redis
Why it's wrong here
ElastiCache is a cache, not a durable data store; data loss can occur.
Amazon DynamoDB
Why this is correct
DynamoDB offers consistent single-digit millisecond latency at scale.
Related concept
Read the scenario before looking for a memorised answer.
Amazon RDS for MySQL
Why it's wrong here
RDS latency is higher, especially under heavy write loads.
Amazon S3
Why it's wrong here
S3 latency is in the hundreds of milliseconds, not sub-millisecond.
Common exam traps
The trap here is that candidates often choose ElastiCache for Redis because of its sub-millisecond performance, overlooking that the question specifies a 'data store' for a write-heavy workload, which requires durability and persistence that Redis does not guarantee by default, whereas DynamoDB is a fully managed, durable database designed for such use cases.
Detailed technical explanation
DynamoDB achieves sub-millisecond latency through its SSD-backed storage and distributed hash table architecture, where data is partitioned across multiple nodes using consistent hashing. For even lower latency, DAX provides an in-memory cache that can reduce read latency to microseconds, but it does not improve write latency. In a real-world scenario, a gaming leaderboard application requiring real-time score updates and reads would benefit from DynamoDB's ability to handle millions of requests per second with adaptive capacity.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
A media company stores terabytes of video archives that are accessed once a year for audit purposes. Moving these objects to a cold storage tier (Azure Archive, S3 Glacier, or Google Nearline) costs a fraction of hot storage. Questions like this test whether you understand storage tiers, access frequency tradeoffs, and retrieval latency requirements.
What to study next
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FAQ
Data Store Management — This question tests Data Store Management — Read the scenario before looking for a memorised answer..
The correct answer is: Amazon DynamoDB — 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.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 24, 2026
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.
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