- A
Enable Server-Side Encryption on the S3 bucket
Encrypts objects at rest.
- B
Enable S3 Transfer Acceleration
Why wrong: Acceleration improves speed, not encryption.
- C
Enforce HTTPS for all S3 API requests using bucket policy
Ensures data is encrypted in transit.
- D
Use client-side encryption before uploading
Why wrong: Not required; server-side encryption is sufficient.
- E
Use S3 VPC Endpoint
Why wrong: VPC endpoints provide private connectivity but do not encrypt.
Question 355 of 1,755
MLS-C01 Data Engineering Practice Question
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 company is designing a data pipeline to ingest data from multiple sources into an Amazon S3 data lake. The data must be encrypted at rest and in transit. Which TWO actions should be taken to meet these requirements?
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 Server-Side Encryption on the S3 bucket
Option A is correct because enabling Server-Side Encryption (SSE-S3 or SSE-KMS) on the S3 bucket automatically encrypts data at rest when written to disk, using AES-256 encryption. This meets the requirement for encryption at rest without any client-side changes.
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 Server-Side Encryption on the S3 bucket
Why this is correct
Encrypts objects at rest.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Enable S3 Transfer Acceleration
Why it's wrong here
Acceleration improves speed, not encryption.
- ✓
Enforce HTTPS for all S3 API requests using bucket policy
Why this is correct
Ensures data is encrypted in transit.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Use client-side encryption before uploading
Why it's wrong here
Not required; server-side encryption is sufficient.
- ✗
Use S3 VPC Endpoint
Why it's wrong here
VPC endpoints provide private connectivity but do not encrypt.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse S3 Transfer Acceleration or VPC Endpoints with encryption features, or mistakenly think client-side encryption is required alongside server-side encryption, when the simplest AWS-native pair is SSE + HTTPS enforcement.
Detailed technical explanation
How to think about this question
Server-Side Encryption (SSE-S3) uses AES-256 with an S3-managed key, while SSE-KMS provides envelope encryption with a KMS-managed key and audit trail. Enforcing HTTPS via bucket policy (using the `aws:SecureTransport` condition key) ensures all API requests use TLS 1.2+ in transit, preventing plaintext HTTP access. Together, these two actions cover both encryption at rest (SSE) and in transit (HTTPS enforcement) without requiring client-side changes.
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 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
Symmetric Encryption Algorithm Comparison
| Algorithm | Key Size | Block Size | Status | Notes |
|---|---|---|---|---|
| AES-128 | 128-bit | 128-bit | Current standard | NIST approved; WPA3, TLS |
| AES-256 | 256-bit | 128-bit | Current standard | Preferred for sensitive / govt data |
| 3DES | 112-bit effective | 64-bit | Deprecated (2023) | Replaced by AES |
| DES | 56-bit | 64-bit | Broken | Cracked in < 24 h; never deploy |
| ChaCha20 | 256-bit | Stream cipher | Current | TLS 1.3, WireGuard |
What to study next
Got this wrong? Here's your next step.
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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 Server-Side Encryption on the S3 bucket — Option A is correct because enabling Server-Side Encryption (SSE-S3 or SSE-KMS) on the S3 bucket automatically encrypts data at rest when written to disk, using AES-256 encryption. This meets the requirement for encryption at rest without any client-side changes.
What should I do if I get this MLS-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.
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Last reviewed: Jul 4, 2026
This MLS-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 MLS-C01 exam.
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