The answer is that the S3 bucket policy does not deny requests that omit the encryption header. This is the most likely cause of the encryption enforcement failure because the policy’s Deny statement uses the condition `StringNotEquals s3:x-amz-server-side-encryption AES256`, which only evaluates to true when the header is present but set to a value other than AES256. If a user uploads an object without including the encryption header at all, the condition key does not exist, the condition evaluates to false, and the Deny is never triggered—allowing unencrypted uploads to succeed. On the AWS Certified Solutions Architect Professional SAP-C02 exam, this scenario tests your understanding of how S3 policy evaluation works with missing condition keys, a common trap where candidates assume a Deny statement covers all non-compliant cases. The key memory tip is: “No header means no condition match—Deny never fires.”
SAP-C02 Design for New Solutions Practice Question
This SAP-C02 practice question tests your understanding of design for new 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.
Refer to the exhibit. A company has an S3 bucket policy that requires server-side encryption with AES256 for all objects uploaded. However, users can still upload objects without encryption. What is the MOST likely reason?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "most likely"
Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The policy does not deny requests that omit the encryption header
Option C is correct because the policy has a Deny with a condition but also an Allow with the same condition. The Allow statement effectively overrides the Deny because the Deny only applies when encryption is not AES256, but the Allow applies when encryption is AES256. However, the issue is that the Deny statement is not denying all non-compliant uploads because the Allow statement is too permissive. Actually, the correct interpretation: The Deny statement denies PutObject when encryption is not AES256. The Allow statement allows PutObject when encryption is AES256. However, without the Allow, the default is implicit deny. The Allow statement is redundant but not harmful. The problem might be that the policy is missing a condition to also require encryption for existing objects? But the real issue is that the policy does not deny requests that do not include the encryption header at all. The condition "StringNotEquals" only matches when the header is present but not equal to AES256. If no encryption header is present, the condition evaluates to true because the value is not present? Actually, if the header is missing, the condition key does not exist, and the condition evaluates to false. So the Deny does not apply when no encryption header is present. Therefore, users can upload without encryption. Option C correctly identifies this: the policy does not deny requests that omit the encryption header. Option A is incorrect because bucket policy can enforce encryption. Option B is incorrect because the condition is correct. Option D is incorrect because AWS managed keys are not relevant.
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.
✗
S3 bucket policies cannot enforce encryption; you must use bucket default encryption
Why it's wrong here
Bucket policies can enforce encryption via conditions.
✗
The condition key is incorrect; it should be s3:x-amz-server-side-encryption-aws-kms-key-id
Why it's wrong here
The condition key is correct for AES256.
✗
The policy does not apply to objects uploaded using AWS KMS managed keys
Why it's wrong here
AES256 is SSE-S3, not KMS.
✓
The policy does not deny requests that omit the encryption header
Why this is correct
If no encryption header is present, the condition evaluates to false, so Deny does not apply.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
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 SAP-C02 ACL questions on filtering logic and placement.
Design for New Solutions — This question tests Design for New Solutions — Standard ACLs match source addresses..
What is the correct answer to this question?
The correct answer is: The policy does not deny requests that omit the encryption header — Option C is correct because the policy has a Deny with a condition but also an Allow with the same condition. The Allow statement effectively overrides the Deny because the Deny only applies when encryption is not AES256, but the Allow applies when encryption is AES256. However, the issue is that the Deny statement is not denying all non-compliant uploads because the Allow statement is too permissive. Actually, the correct interpretation: The Deny statement denies PutObject when encryption is not AES256. The Allow statement allows PutObject when encryption is AES256. However, without the Allow, the default is implicit deny. The Allow statement is redundant but not harmful. The problem might be that the policy is missing a condition to also require encryption for existing objects? But the real issue is that the policy does not deny requests that do not include the encryption header at all. The condition "StringNotEquals" only matches when the header is present but not equal to AES256. If no encryption header is present, the condition evaluates to true because the value is not present? Actually, if the header is missing, the condition key does not exist, and the condition evaluates to false. So the Deny does not apply when no encryption header is present. Therefore, users can upload without encryption. Option C correctly identifies this: the policy does not deny requests that omit the encryption header. Option A is incorrect because bucket policy can enforce encryption. Option B is incorrect because the condition is correct. Option D is incorrect because AWS managed keys are not relevant.
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.
Are there clue words in this question I should notice?
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
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 security engineer created the S3 bucket policy shown in the exhibit. The policy is intended to allow the role MyAppRole to get objects only if they are encrypted with SSE-S3. However, the role is getting access denied errors when trying to get objects that are encrypted with SSE-S3. What is the most likely cause?
hard
A.The Principal is incorrect; it should be the role name, not ARN.
B.The Resource ARN is incorrect; it should be 'arn:aws:s3:::my-bucket'.
C.The condition key is misspelled.
✓ D.The condition key 's3:x-amz-server-side-encryption' checks the request header, not the object's encryption state.
Why D: Option A is correct. The s3:x-amz-server-side-encryption condition key is a request header, not a property of the object. SSE-S3 encryption is applied by default, but the condition checks for the request header, which is not present when the object is already encrypted server-side. Option B is wrong because the resource is correct. Option C is wrong because the condition key is valid. Option D is wrong because the role ARN is correctly specified.
Last reviewed: Jun 20, 2026
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