S3 Encryption at Rest and Access Auditing
A data engineer is designing a data pipeline that processes sensitive personal data. The data is ingested via Amazon Kinesis Data Firehose and stored in Amazon S3. The pipeline must ensure that the data is encrypted at rest and in transit. The engineer also needs to audit access to the data. Which combination of services meets these requirements?
Quick Answer
The correct answer is S3 server-side encryption (SSE-S3) for at-rest encryption, HTTPS for in-transit encryption, and AWS CloudTrail for auditing. This combination works because SSE-S3 encrypts data at the object level as it is written to Amazon S3, HTTPS secures the data during ingestion from Kinesis Data Firehose, and CloudTrail records all S3 API calls—such as GetObject and PutObject—to provide a detailed audit trail of who accessed the data and when. On the AWS Certified Data Engineer Associate DEA-C01 exam, this question tests your ability to distinguish between services that handle data protection versus configuration or monitoring: a common trap is confusing CloudWatch Logs (which monitors performance metrics) or AWS Config (which tracks resource compliance) with CloudTrail’s specific role in auditing data access. For a quick memory tip, think “SSE + HTTPS + Trails” to recall the three pillars of encryption and auditing for sensitive data in S3.
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
✓
S3 server-side encryption (SSE-S3) for at-rest encryption, HTTPS for in-transit encryption, and AWS CloudTrail for auditing.
S3 server-side encryption (SSE-S3) encrypts data at rest in S3. HTTPS (TLS) encrypts data in transit between the data source and Kinesis Data Firehose, and between Firehose and S3. AWS CloudTrail logs S3 API calls (e.g., GetObject, PutObject) for auditing data access. Option A is incorrect because Kinesis Data Analytics does not provide encryption in transit; it processes data but does not handle encryption. Option B is incorrect because CloudWatch Logs is for monitoring and storing logs, not for auditing data access; CloudTrail is the appropriate service for auditing. Option D is incorrect because client-side encryption requires manual key management and does not use AWS-managed encryption; AWS Config tracks configuration changes, not data access.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
AWS KMS for encryption at rest, Kinesis Data Analytics for in-transit encryption, and AWS CloudTrail for auditing.
Why it's wrong here
Kinesis Data Analytics does not provide encryption; it processes data.
- ✗
AWS KMS for encryption at rest, Amazon CloudWatch Logs for auditing, and TLS for in-transit encryption.
Why it's wrong here
CloudWatch Logs does not audit S3 data access; CloudTrail is needed.
- ✓
S3 server-side encryption (SSE-S3) for at-rest encryption, HTTPS for in-transit encryption, and AWS CloudTrail for auditing.
Why this is correct
SSE-S3 encrypts objects at rest, HTTPS encrypts data in transit, and CloudTrail logs S3 API operations for auditing.
- ✗
S3 client-side encryption, AWS Config for auditing, and TLS for in-transit encryption.
Why it's wrong here
AWS Config does not audit data access; it records configuration changes.
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 |
Go deeper
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Same concept, more angles
1 more way this is tested on DEA-C01
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Variation 1. A data engineer needs to ensure that sensitive data stored in Amazon S3 is encrypted at rest. Which TWO options meet this requirement? (Choose TWO.)
medium- ✓ A.Server-Side Encryption with AWS KMS-Managed Keys (SSE-KMS)
- ✓ B.Server-Side Encryption with S3-Managed Keys (SSE-S3)
- C.Using a VPC to restrict network access
- D.Enabling MFA Delete on the S3 bucket
- E.Client-Side Encryption with SSL/TLS
Why A: Server-Side Encryption with AWS KMS-Managed Keys (SSE-KMS) allows you to enforce encryption at rest for S3 objects using a customer-managed or AWS-managed KMS key. This option meets the requirement because the encryption is applied server-side by S3 before the data is written to disk, and the data is decrypted automatically when accessed with appropriate permissions. SSE-KMS also provides an audit trail via AWS CloudTrail for every key usage.
JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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.