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 needs to store JSON documents that are accessed by a serverless application using AWS Lambda. The documents are frequently updated and need low latency (single-digit milliseconds) for read and write operations. Which AWS service should the engineer use?
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 a fully managed NoSQL key-value and document database that provides single-digit millisecond latency for read and write operations at any scale. It natively supports JSON documents, integrates directly with AWS Lambda via the AWS SDK, and handles frequent updates efficiently through its auto-scaling and on-demand capacity modes, making it ideal for serverless applications requiring low-latency data access.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
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 DynamoDB
Why this is correct
DynamoDB offers single-digit millisecond latency for reads and writes and supports JSON documents natively.
Related concept
Read the scenario before looking for a memorised answer.
✗
Amazon ElastiCache for Redis
Why it's wrong here
ElastiCache is a cache, not a durable data store; data can be lost if not persisted.
✗
Amazon S3 (with S3 Select)
Why it's wrong here
S3 has higher latency and is not designed for frequent updates; S3 Select is for querying, not low-latency writes.
✗
Amazon RDS for MySQL
Why it's wrong here
RDS is relational and may have higher latency; JSON support is not as native as DynamoDB.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse ElastiCache for Redis as a primary data store due to its low latency, overlooking that it is an in-memory cache with no built-in persistence guarantees, whereas DynamoDB provides both low latency and durable, persistent storage for JSON documents.
Detailed technical explanation
How to think about this question
DynamoDB achieves single-digit millisecond latency through its distributed architecture where data is automatically partitioned across multiple storage nodes using a hash of the partition key, and each partition is replicated across three Availability Zones for durability. The service uses solid-state drives (SSDs) for storage and maintains a consistent hash ring to route requests directly to the correct partition, avoiding the overhead of a central query engine. In practice, a serverless application using Lambda can achieve sub-10ms reads and writes by using the DynamoDB API with consistent reads (or even lower latency with eventually consistent reads) and by designing access patterns around the primary key to avoid full table scans.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
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
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Data Store Management — This question tests Data Store Management — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Amazon DynamoDB — Amazon DynamoDB is a fully managed NoSQL key-value and document database that provides single-digit millisecond latency for read and write operations at any scale. It natively supports JSON documents, integrates directly with AWS Lambda via the AWS SDK, and handles frequent updates efficiently through its auto-scaling and on-demand capacity modes, making it ideal for serverless applications requiring low-latency data access.
What should I do if I get this DEA-C01 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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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.
Question Discussion
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