The answer is to enable default encryption on each S3 bucket. This is correct because S3 default encryption, configured at the bucket level, automatically applies server-side encryption to every object uploaded, ensuring all data at rest is encrypted without requiring any changes to client applications or upload processes. On the AWS Certified Solutions Architect Professional SAP-C02 exam, this scenario tests your understanding of preventive controls versus detective controls—a common trap is choosing AWS Config, which can detect noncompliant buckets but cannot enforce encryption, or a bucket policy that requires per-bucket management and can be bypassed by unencrypted PUTs. Another pitfall is assuming an IAM policy can enforce encryption at the bucket level, which it cannot. To enforce S3 server-side encryption across all buckets, remember the memory tip: "Default is direct; Config is detective."
SAP-C02 Continuous Improvement for Existing Solutions Practice Question
This SAP-C02 practice question tests your understanding of continuous improvement for existing solutions. 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 uses Amazon S3 to store sensitive data. The security team requires that all S3 buckets have server-side encryption enabled. How can the company enforce this across all existing and future buckets?
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 B is correct because S3 default encryption can be set at the bucket level for all objects. Option A is wrong because bucket policies can enforce encryption but require a policy per bucket. Option C is wrong because AWS Config can detect noncompliant buckets but not enforce encryption. Option D is wrong because IAM policies cannot enforce encryption on S3 buckets.
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 default encryption on each S3 bucket.
Why this is correct
Default encryption ensures all new objects are encrypted.
Related concept
Standard ACLs match source addresses.
✗
Create an IAM policy that denies s3:PutObject unless encryption headers are present.
Why it's wrong here
IAM policies apply to users, not buckets.
✗
Use an S3 bucket policy to deny PutObject without encryption.
Why it's wrong here
This applies per bucket and requires manual setup.
✗
Use AWS Config to automatically remediate noncompliant buckets.
Why it's wrong here
Config can detect but not enable default encryption automatically.
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 SAP-C02 ACL questions on filtering logic and placement.
Continuous Improvement for Existing Solutions — This question tests Continuous Improvement for Existing Solutions — 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 B is correct because S3 default encryption can be set at the bucket level for all objects. Option A is wrong because bucket policies can enforce encryption but require a policy per bucket. Option C is wrong because AWS Config can detect noncompliant buckets but not enforce encryption. Option D is wrong because IAM policies cannot enforce encryption on S3 buckets.
What should I do if I get this SAP-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 SAP-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
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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 requires that all objects be encrypted at rest. The company currently uses server-side encryption with S3-managed keys (SSE-S3). The security team wants to ensure that only authorized users can access the decryption keys. What should the company do?
easy
A.Configure an S3 bucket policy to allow only specific IAM roles to put objects.
B.Continue using SSE-S3 and enable S3 Block Public Access.
C.Use client-side encryption with an AWS KMS key.
✓ D.Change the default encryption to server-side encryption with AWS KMS (SSE-KMS) and apply IAM policies to control key usage.
Why D: Option C is correct because SSE-KMS provides centralized key management and access control. Option A is wrong because SSE-S3 keys are managed by AWS, not the customer. Option B is wrong because client-side encryption does not use S3 server-side encryption. Option D is wrong because bucket policies control access to objects, not encryption keys.
Variation 2. A company uses Amazon S3 to store sensitive data. The security team requires that all S3 buckets be encrypted at rest using SSE-KMS. The company has thousands of existing buckets, some of which are not encrypted. Which approach will enforce encryption on all buckets with minimal effort?
medium
A.Use S3 default encryption to automatically encrypt new objects.
B.Use an AWS Config rule to check for encryption and automatically remediate by enabling SSE-S3.
✓ C.Use an SCP to deny creation of buckets without SSE-KMS and use an AWS Config rule with remediation to enable SSE-KMS on existing buckets.
D.Create an AWS Lambda function that scans all buckets and enables encryption.
Why C: Option D is correct because an SCP can deny creation of unencrypted buckets and AWS Config can remediate existing buckets. Option A is wrong because a Lambda function is reactive, not proactive. Option B is wrong because S3 default encryption is not applied retroactively. Option C is wrong because SSE-S3 does not meet the KMS requirement.
Variation 3. A company is using Amazon S3 to store sensitive data. The security team requires that all data be encrypted at rest using server-side encryption with AWS KMS. The company also needs to ensure that any attempt to upload an unencrypted object is blocked. How can the company enforce this requirement?
easy
✓ A.Use a bucket policy that denies s3:PutObject if the request does not include the x-amz-server-side-encryption header with value aws:kms
B.Enable default encryption on the bucket with AWS KMS
C.Use AWS CloudTrail to monitor PutObject calls and alert on unencrypted uploads
D.Enable S3 Object Lock on the bucket
Why A: Option B is correct because a bucket policy that denies PutObject without x-amz-server-side-encryption header set to aws:kms will enforce encryption at upload time. Option A is not possible at the bucket level. Option C (default encryption) does not enforce on existing uploads if the header is omitted. Option D (CloudTrail) is detective, not preventive.
Variation 4. A company is using Amazon S3 to store sensitive data. The security team wants to ensure that all objects uploaded to specific S3 buckets are encrypted at rest. Which TWO actions should they take? (Choose 2)
medium
✓ A.Use a bucket policy that denies PutObject without the x-amz-server-side-encryption header.
✓ B.Configure default encryption on the S3 buckets to use SSE-S3 or SSE-KMS.
C.Enable S3 Cross-Region Replication.
D.Enable S3 Versioning on the buckets.
E.Enable S3 Server Access Logs.
Why A: Options B and D are correct. B enforces encryption at upload time, and D provides server-side encryption. A does not enforce encryption, C is about access logging, and E is about replication.
Variation 5. A company is using Amazon S3 to store sensitive data. The security team wants to ensure that all objects are encrypted at rest. The company currently uses server-side encryption with S3 managed keys (SSE-S3). The team wants to enforce encryption using a customer-managed key (CMK) from AWS KMS. Which TWO actions should the team take?
medium
✓ A.Configure a bucket policy that denies PutObject if the x-amz-server-side-encryption header is not set to 'aws:kms'.
B.Enable AWS CloudTrail to audit all PutObject requests.
✓ C.Enable default encryption on the bucket with AWS KMS (SSE-KMS) as the encryption type.
D.Configure a bucket policy that allows PutObject only if the object is encrypted.
E.Disable SSE-S3 on the bucket so that only SSE-KMS can be used.
Why A: Option A and Option C are correct. Option A (S3 Bucket Policy denying PutObject without the correct encryption header) enforces encryption at upload time. Option C (Default encryption with SSE-KMS) ensures that objects uploaded without encryption headers are encrypted with KMS. Option B (Bucket policy allowing any encryption) does not enforce KMS. Option D (Disable SSE-S3) is not possible; you cannot disable SSE-S3, you can only set default encryption. Option E (CloudTrail logging) does not enforce encryption.
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