The answer is Amazon Timestream and Amazon DynamoDB with TTL. Timestream is purpose-built for time-series sub-millisecond latency data stores, offering automatic tiering between in-memory and magnetic storage to handle hundreds of terabytes while maintaining fast query performance. DynamoDB, when combined with a TTL-based expiration strategy, can also serve time-series workloads at sub-millisecond latency, though it requires careful partition key design to avoid hot spots. On the AWS Certified Data Engineer Associate DEA-C01 exam, this question tests your ability to distinguish between specialized time-series services and general-purpose NoSQL options, with a common trap being ElastiCache—it offers sub-millisecond latency but cannot scale to hundreds of terabytes due to memory constraints, while Redshift and RDS are too slow for real-time writes. Remember the mnemonic “Timestream for time, Dynamo for data” to pair the two services that balance latency and scale.
DEA-C01 Data Store Management Practice Question
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 for time-series data. The data volume is expected to grow to hundreds of terabytes. Which TWO AWS services should the engineer consider? (Choose TWO.)
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Amazon DynamoDB with Time-to-Live (TTL)
Options A and D are correct. Amazon Timestream is a time-series database with fast query performance; Amazon DynamoDB with TTL can handle time-series data, but for sub-millisecond latency, DynamoDB is suitable. Option B (Redshift) is for analytics, not sub-millisecond; Option C (RDS) is relational and slower for time-series; Option E (ElastiCache) is in-memory but limited by memory size for hundreds of terabytes.
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 Redshift
Why it's wrong here
Redshift is for analytical queries, not sub-millisecond latency.
✓
Amazon DynamoDB with Time-to-Live (TTL)
Why this is correct
DynamoDB supports low-latency reads/writes and TTL for automatic expiration of old data.
Related concept
Read the scenario before looking for a memorised answer.
✗
Amazon ElastiCache for Redis
Why it's wrong here
ElastiCache is in-memory and limited by cluster memory size; hundreds of terabytes would be costly.
✗
Amazon RDS for PostgreSQL
Why it's wrong here
RDS is not optimized for time-series and may not achieve sub-millisecond latency at scale.
✓
Amazon Timestream
Why this is correct
Timestream is purpose-built for time-series data and provides low-latency queries.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Many certification questions include familiar terms but test a specific constraint. Read the exact wording before choosing an answer that is generally true but wrong for this case.
Detailed technical explanation
How to think about this question
This question should be treated as a scenario, not a definition check. Identify the problem, the constraint and the best action. Then compare each option against those facts.
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.
Use explanations to understand the rule behind the answer.
TExam Day Tips
→Underline the problem statement mentally.
→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 cloud solutions architect for a retail company is evaluating services for a new workload. The correct answer here reflects best practice for the specific scenario described — not a general cloud recommendation. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Cloud exam questions reward reading the constraint carefully: the same technology can be right or wrong depending on the use case.
What to study next
Got this wrong? Here's your next step.
Identify which DEA-C01 exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
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 with Time-to-Live (TTL) — Options A and D are correct. Amazon Timestream is a time-series database with fast query performance; Amazon DynamoDB with TTL can handle time-series data, but for sub-millisecond latency, DynamoDB is suitable. Option B (Redshift) is for analytics, not sub-millisecond; Option C (RDS) is relational and slower for time-series; Option E (ElastiCache) is in-memory but limited by memory size for hundreds of terabytes.
What should I do if I get this DEA-C01 question wrong?
Identify which DEA-C01 exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
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 time-series application that requires sub-millisecond read latency for the latest data and high ingestion rates. Which AWS service is most suitable?
medium
A.Amazon DynamoDB
B.Amazon ElastiCache for Redis
C.Amazon RDS for PostgreSQL
✓ D.Amazon Timestream
Why D: Option A is correct because Amazon Timestream is a fast, scalable, serverless time-series database. Option B is wrong because Amazon RDS is not optimized for time-series workloads. Option C is wrong because Amazon DynamoDB is a key-value store, not purpose-built for time-series. Option D is wrong because Amazon ElastiCache is a caching layer, not a primary datastore for time-series.
Last reviewed: Jun 20, 2026
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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.
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