The answer is creating a bucket policy that denies s3:PutObject without the x-amz-server-side-encryption header and enabling S3 Server-Side Encryption (SSE). These two measures directly enforce encryption of data at rest in Amazon S3, ensuring that all objects written to the bucket are encrypted before storage. The bucket policy acts as a guardrail, rejecting any upload that lacks the required encryption header, while SSE handles the actual encryption of the stored data using AES-256 or AWS KMS keys. On the AWS Certified DevOps Engineer Professional DOP-C02 exam, this question tests your understanding of data protection controls versus operational features; common traps include confusing MFA Delete (which protects against deletion, not encryption) or cross-region replication (a disaster recovery tool) with at-rest encryption. Remember the key distinction: at-rest protection always involves encryption, not replication or access control alone. A useful memory tip is “Policy plus SSE equals encrypted rest,” linking the two correct choices as complementary layers for securing S3 data at rest.
DOP-C02 Security and Compliance Practice Question
This DOP-C02 practice question tests your understanding of security and compliance. 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.
Which TWO measures can be taken to protect data at rest in Amazon S3? (Select TWO.)
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Enable S3 Server-Side Encryption (SSE-S3 or SSE-KMS)
S3 Server-Side Encryption (SSE) and S3 Bucket Policies to deny unencrypted PUT requests are measures to protect data at rest. MFA Delete protects against accidental deletion, not encryption. Cross-region replication is for disaster recovery. S3 Transfer Acceleration speeds up uploads.
Key principle: ACLs process entries top to bottom and stop at the first match. Entry order and interface direction matter as much as the permit or deny statement.
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 Server-Side Encryption (SSE-S3 or SSE-KMS)
MFA Delete protects against deletion, not data at rest.
✓
Create a bucket policy that denies s3:PutObject without the x-amz-server-side-encryption header
Why this is correct
This enforces encryption on upload.
Related concept
Standard ACLs match source addresses.
✗
Use S3 Transfer Acceleration
Why it's wrong here
Transfer Acceleration speeds up transfers, does not protect data at rest.
Common exam traps
Common exam trap: ACLs stop at the first match
ACLs are processed top to bottom. The first matching entry wins, and an implicit deny usually exists at the end.
Detailed technical explanation
How to think about this question
ACL questions test precision: source, destination, protocol, port and direction. A generally correct ACL can still fail if it is applied on the wrong interface or in the wrong direction.
KKey Concepts to Remember
Standard ACLs match source addresses.
Extended ACLs can match source, destination, protocol and ports.
The first matching ACL entry is used.
There is usually an implicit deny at the end.
TExam Day Tips
→Check inbound versus outbound direction.
→Read the ACL from top to bottom.
→Look for a broader permit or deny above the intended line.
Key takeaway
ACLs process entries top to bottom and stop at the first match. Entry order and interface direction matter as much as the permit or deny statement.
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.
What to study next
Got this wrong? Here's your next step.
Review ACL processing order, placement rules (standard near destination, extended near source), and inbound vs outbound direction. Study wildcard masks and implicit deny. Then practise related DOP-C02 ACL questions on filtering logic and placement.
Security and Compliance — This question tests Security and Compliance — Standard ACLs match source addresses..
What is the correct answer to this question?
The correct answer is: Enable S3 Server-Side Encryption (SSE-S3 or SSE-KMS) — S3 Server-Side Encryption (SSE) and S3 Bucket Policies to deny unencrypted PUT requests are measures to protect data at rest. MFA Delete protects against accidental deletion, not encryption. Cross-region replication is for disaster recovery. S3 Transfer Acceleration speeds up uploads.
What should I do if I get this DOP-C02 question wrong?
Review ACL processing order, placement rules (standard near destination, extended near source), and inbound vs outbound direction. Study wildcard masks and implicit deny. Then practise related DOP-C02 ACL questions on filtering logic and placement.
What is the key concept behind this question?
Standard ACLs match source addresses.
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Question Discussion
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