The answer is Amazon S3 Glacier Deep Archive, the most cost-effective storage solution for CloudTrail logs that are append-only and rarely accessed after 90 days. This choice leverages the principle of lifecycle management: after the initial 90-day period, the logs transition from a standard tier to Glacier Deep Archive, which offers the lowest storage cost in AWS at roughly $0.00099 per GB/month, compared to S3 Standard’s $0.023 per GB/month. Since the logs are semi-structured JSON and accessed at most once or twice per year, the 12–48 hour retrieval time is perfectly acceptable, making this a textbook example of cost-effective storage for rarely accessed logs. On the AWS Certified Data Engineer Associate DEA-C01 exam, this scenario tests your understanding of S3 storage classes and lifecycle policies, often appearing as a trap where candidates mistakenly choose S3 Glacier Flexible Retrieval due to faster retrieval, ignoring the “rarely accessed” and “cost-effective” keywords. Remember the memory tip: “Deep Archive for deep discounts on dead data.”
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 needs to store semi-structured JSON logs from AWS CloudTrail. The logs are append-only and rarely accessed after 90 days. Which storage solution is MOST cost-effective?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Amazon S3 Glacier Deep Archive
Amazon S3 Glacier Deep Archive is the most cost-effective storage solution for CloudTrail logs that are append-only and rarely accessed after 90 days. It offers the lowest storage cost among AWS options (approximately $0.00099 per GB/month) and is designed for data that is accessed at most once or twice per year, with retrieval times of 12–48 hours. Since the logs are rarely accessed after 90 days, the retrieval latency is acceptable, and the cost savings over S3 Standard (which costs ~$0.023 per GB/month) are substantial.
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 S3 Glacier Deep Archive
Why this is correct
Glacier Deep Archive offers the lowest cost for long-term archival data.
Related concept
Read the scenario before looking for a memorised answer.
✗
Amazon S3 Standard
Why it's wrong here
S3 Standard is more expensive for data that is rarely accessed after 90 days.
✗
Amazon EBS with cold HDD volumes
Why it's wrong here
EBS is not designed for log storage and is more expensive than S3.
✗
Amazon DynamoDB with on-demand capacity
Why it's wrong here
DynamoDB is not cost-effective for large volumes of rarely accessed log data.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates may choose S3 Standard or DynamoDB because they assume CloudTrail logs need frequent querying, but the question explicitly states 'rarely accessed after 90 days,' making Glacier Deep Archive the correct cost-optimal choice despite its longer retrieval time.
Detailed technical explanation
How to think about this question
Glacier Deep Archive uses a distributed, erasure-coded storage system that provides 99.999999999% durability by replicating data across multiple Availability Zones. Retrieval times are typically 12–48 hours for standard retrievals, but expedited retrievals (1–5 minutes) are available at higher cost, which is rarely needed for audit logs. A real-world scenario is storing CloudTrail logs for compliance (e.g., SOC 2, PCI DSS) where retention periods of 1–7 years are required, and Glacier Deep Archive reduces storage costs by up to 90% compared to S3 Standard-IA.
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 Glacier Deep Archive — Amazon S3 Glacier Deep Archive is the most cost-effective storage solution for CloudTrail logs that are append-only and rarely accessed after 90 days. It offers the lowest storage cost among AWS options (approximately $0.00099 per GB/month) and is designed for data that is accessed at most once or twice per year, with retrieval times of 12–48 hours. Since the logs are rarely accessed after 90 days, the retrieval latency is acceptable, and the cost savings over S3 Standard (which costs ~$0.023 per GB/month) are substantial.
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.
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 needs to store semi-structured JSON transaction logs for analytics. The logs are written once and rarely accessed. The storage must be cost-effective. Which AWS service should be used?
easy
✓ A.Amazon S3
B.Amazon DynamoDB
C.Amazon RDS
D.Amazon Redshift
Why A: Amazon S3 is the correct choice because it provides highly durable, cost-effective object storage ideal for semi-structured JSON transaction logs that are written once and rarely accessed. S3's lifecycle policies can automatically transition such infrequently accessed data to S3 Glacier or S3 Glacier Deep Archive for even lower storage costs, making it the most economical option for this use case.
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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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