- A
Enable S3 default encryption with SSE-KMS and enable AWS CloudTrail for S3 data events.
SSE-KMS provides encryption with managed keys; CloudTrail logs data events for auditing.
- B
Use IAM policies to control access and enable S3 server access logging.
Why wrong: IAM policies control access but do not encrypt data.
- C
Use SSL/TLS for all connections and enable S3 versioning.
Why wrong: Versioning helps with retention but not encryption at rest.
- D
Enable S3 default encryption with SSE-S3 and use S3 access logs.
Why wrong: SSE-S3 does not provide customer-managed keys, and access logs are not as detailed as CloudTrail.
Question 851 of 1,755
Data Lake Encryption and Auditing: Regulatory Compliance
This MLS-C01 practice question tests your understanding of data engineering. 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 financial services company needs to build a data lake on Amazon S3 that meets regulatory requirements for data retention and encryption. Data must be encrypted at rest and in transit, and access must be audited. The data lake will be queried by Amazon Athena and Amazon Redshift Spectrum. Which combination of actions should be taken?
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Enable S3 default encryption with SSE-KMS and enable AWS CloudTrail for S3 data events.
Option A is correct because S3 default encryption with SSE-KMS provides encryption at rest with customer-managed keys, and enabling AWS CloudTrail for S3 data events provides comprehensive auditing of access to the data lake. This combination meets the regulatory requirements for data retention, encryption, and audit. Option B is incorrect because SSL/TLS only ensures encryption in transit, and versioning does not provide encryption at rest or auditing. Option C is incorrect because IAM policies control access but do not provide encryption. Option D is incorrect because SSE-S3 does not allow key management control, which may be required, and S3 access logs are less detailed than CloudTrail for auditing.
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.
- ✓
Enable S3 default encryption with SSE-KMS and enable AWS CloudTrail for S3 data events.
Why this is correct
SSE-KMS provides encryption with managed keys; CloudTrail logs data events for auditing.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Use IAM policies to control access and enable S3 server access logging.
Why it's wrong here
IAM policies control access but do not encrypt data.
- ✗
Use SSL/TLS for all connections and enable S3 versioning.
Why it's wrong here
Versioning helps with retention but not encryption at rest.
- ✗
Enable S3 default encryption with SSE-S3 and use S3 access logs.
Why it's wrong here
SSE-S3 does not provide customer-managed keys, and access logs are not as detailed as CloudTrail.
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 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.
Quick reference
AWS S3 Storage Class Comparison
| Storage Class | Min Duration | Retrieval | Use Case |
|---|---|---|---|
| S3 Standard | None | Immediate | Frequently accessed data |
| S3 Standard-IA | 30 days | Immediate | Infrequent access, rapid retrieval |
| S3 One Zone-IA | 30 days | Immediate | Non-critical infrequent data |
| S3 Intelligent-Tiering | None | Immediate–hours | Unknown or changing access patterns |
| S3 Glacier Instant | 90 days | Milliseconds | Archive with instant retrieval |
| S3 Glacier Flexible | 90 days | Minutes–hours | Archive, flexible retrieval |
| S3 Glacier Deep Archive | 180 days | Hours | Long-term compliance archive |
What to study next
Got this wrong? Here's your next step.
Identify which MLS-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.
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FAQ
Questions learners often ask
What does this MLS-C01 question test?
Data Engineering — This question tests Data Engineering — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Enable S3 default encryption with SSE-KMS and enable AWS CloudTrail for S3 data events. — Option A is correct because S3 default encryption with SSE-KMS provides encryption at rest with customer-managed keys, and enabling AWS CloudTrail for S3 data events provides comprehensive auditing of access to the data lake. This combination meets the regulatory requirements for data retention, encryption, and audit. Option B is incorrect because SSL/TLS only ensures encryption in transit, and versioning does not provide encryption at rest or auditing. Option C is incorrect because IAM policies control access but do not provide encryption. Option D is incorrect because SSE-S3 does not allow key management control, which may be required, and S3 access logs are less detailed than CloudTrail for auditing.
What should I do if I get this MLS-C01 question wrong?
Identify which MLS-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
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Last reviewed: Jun 20, 2026
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