The correct answer is to enable default encryption on all S3 buckets and use a service control policy (SCP) to deny the s3:PutBucketPublicBlockAccess action, though the SCP should actually deny the ability to create or modify buckets without encryption settings. Enabling default encryption ensures that every new object written to a bucket is automatically encrypted at rest, covering server-side encryption with S3-managed keys (SSE-S3) or AWS KMS. An SCP applied at the organization level can enforce encryption at rest by denying any PutBucketEncryption or PutBucketPublicAccessBlock request that would allow an unencrypted bucket, making it impossible for account administrators to bypass the policy. On the AWS Certified Security Specialty SCS-C02 exam, this tests your understanding of preventive controls versus detective controls—a common trap is confusing bucket policies (which can only deny actions on existing objects) with SCPs (which block the API call itself). Remember the mnemonic: “Default encrypts new, SCP blocks the brew”—default encryption handles future objects, while the SCP stops unencrypted buckets from ever being created.
SCS-C02 Infrastructure Security Practice Question
This SCS-C02 practice question tests your understanding of infrastructure security. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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 needs to enforce that all Amazon S3 buckets are encrypted at rest. Which TWO actions should be taken? (Choose two.)
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Enable default encryption on each S3 bucket.
Option A is correct because enabling default encryption ensures all new objects are encrypted. Option D is correct because an SCP can deny creation of unencrypted buckets. Option B is wrong because bucket policies cannot enforce encryption on existing objects. Option C is wrong because CloudTrail logs do not enforce encryption. Option E is wrong because KMS keys are used for encryption but do not enforce the policy.
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 AWS CloudTrail to log S3 API calls.
Why it's wrong here
CloudTrail logs do not enforce encryption.
✗
Use bucket policies to deny write operations without encryption.
Why it's wrong here
Bucket policies can enforce encryption on uploads but not on existing objects.
✓
Enable default encryption on each S3 bucket.
Why this is correct
Default encryption encrypts new objects.
Related concept
Standard ACLs match source addresses.
✗
Create a KMS key and apply it to all buckets.
Why it's wrong here
KMS key does not enforce encryption; it's just a key.
✓
Use a service control policy (SCP) to deny the s3:PutBucketPublicAccessBlock action.
Why this is correct
SCP can deny creation of buckets without encryption settings.
Related concept
Standard ACLs match source addresses.
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 SCS-C02 ACL questions on filtering logic and placement.
Infrastructure Security — This question tests Infrastructure Security — Standard ACLs match source addresses..
What is the correct answer to this question?
The correct answer is: Enable default encryption on each S3 bucket. — Option A is correct because enabling default encryption ensures all new objects are encrypted. Option D is correct because an SCP can deny creation of unencrypted buckets. Option B is wrong because bucket policies cannot enforce encryption on existing objects. Option C is wrong because CloudTrail logs do not enforce encryption. Option E is wrong because KMS keys are used for encryption but do not enforce the policy.
What should I do if I get this SCS-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 SCS-C02 ACL questions on filtering logic and placement.
What is the key concept behind this question?
Standard ACLs match source addresses.
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 company uses Amazon S3 to store sensitive data. The security team wants to ensure that all objects are encrypted at rest. Which feature should they enable on the S3 bucket?
easy
A.Versioning
B.Server access logging
C.Cross-Region Replication
✓ D.Default encryption
Why D: Amazon S3 default encryption ensures that all new objects are encrypted. Option A is correct. Option B is for logging access. Option C is for versioning. Option D is for cross-region replication.
Last reviewed: Jun 20, 2026
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This SCS-C02 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 SCS-C02 exam.
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