The answer is Amazon S3 and S3 Glacier Deep Archive, as these two services provide the most cost-effective immutable storage for IoT data. This is correct because S3’s object storage model inherently supports write-once-read-many (WORM) workloads, delivering 99.999999999% durability, while Glacier Deep Archive offers the lowest storage cost for data that is never updated and rarely accessed. On the AWS Certified Data Engineer Associate DEA-C01 exam, this question tests your understanding of lifecycle policies and storage tier optimization for immutable, high-durability workloads—a common trap is selecting S3 Standard alone, forgetting that Glacier Deep Archive is the true cost-saver for cold IoT data. Remember the memory tip: “S3 for the write, Glacier for the archive—keep your IoT data cold and cheap.”
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 company is designing a data store for IoT sensor data that is written once and never updated. The data must be stored with high durability and low cost. Which TWO AWS storage services are most suitable? (Choose TWO.)
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "never"
Why it matters: Absolute qualifier. True only if the statement has zero exceptions — be cautious of options that seem obvious but break down in edge cases.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Amazon S3
Amazon S3 is correct because it provides 99.999999999% (11 9's) durability, is designed for write-once-read-many (WORM) workloads, and offers low-cost storage tiers suitable for IoT sensor data that is never updated. S3's object storage model and lifecycle policies allow automatic transition to colder storage, making it ideal for immutable data at scale.
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 ElastiCache
Why it's wrong here
ElastiCache is for caching, not durable long-term storage.
✗
Amazon EBS
Why it's wrong here
EBS is block storage for EC2, not cost-effective for IoT data archival.
✓
Amazon S3
Why this is correct
S3 provides 99.999999999% durability and low cost for infrequently accessed data.
Clue confirmation
The clue word "never" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
Amazon DynamoDB
Why it's wrong here
DynamoDB is optimized for frequent reads/writes, not for cheap archival of immutable data.
✓
Amazon S3 Glacier Deep Archive
Why this is correct
Glacier Deep Archive offers the lowest cost for data that is rarely accessed and can tolerate retrieval times of hours.
Clue confirmation
The clue word "never" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often choose DynamoDB (D) for its scalability and low latency, overlooking that the question emphasizes low cost and write-once immutability, where S3 and Glacier Deep Archive are orders of magnitude cheaper per GB stored.
Detailed technical explanation
How to think about this question
S3's durability is achieved through synchronous replication across multiple Availability Zones within a region, using erasure coding (specifically, a 4+2 or 6+3 scheme) to reconstruct data from failures. S3 Glacier Deep Archive extends this with a retrieval time of 12-48 hours and a storage cost of approximately $0.00099 per GB/month, making it the cheapest AWS storage option for data that is rarely accessed. A real-world scenario is storing years of temperature readings from industrial sensors where compliance requires retention but not immediate access.
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 startup's cloud architect reviews their monthly bill and notices costs are higher than expected for a long-running batch job. Switching from on-demand instances to Reserved Instances — or using Spot/Preemptible VMs — can reduce compute costs by up to 72 %. Questions like this test whether you understand the tradeoffs between commitment, flexibility, and cost across cloud pricing models.
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 S3 — Amazon S3 is correct because it provides 99.999999999% (11 9's) durability, is designed for write-once-read-many (WORM) workloads, and offers low-cost storage tiers suitable for IoT sensor data that is never updated. S3's object storage model and lifecycle policies allow automatic transition to colder storage, making it ideal for immutable data at scale.
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.
Are there clue words in this question I should notice?
Yes — watch for: "never". Absolute qualifier. True only if the statement has zero exceptions — be cautious of options that seem obvious but break down in edge cases.
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 →
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
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
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
Sign in to join the discussion.