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Question 337 of 1,705

Network Security, Compliance and Governance →hardMultiple ChoiceObjective-mapped

Quick Answer

The answer is that the SCP denies s3:PutBucketPolicy for all principals except the allowed role, but because SCPs are deny-by-default and the allow list in the SCP does not override the implicit deny, the allowed role is still blocked. The core issue is that SCPs act as a guardrail: they set a maximum permission boundary, and any action not explicitly allowed by the SCP is implicitly denied for all principals, including the role listed in the condition. On the AWS Certified Advanced Networking Specialty ANS-C01 exam, this tests your understanding of how SCPs interact with OU attachments and IAM policies—specifically that an SCP’s explicit allow for a role does not create a positive grant; it only removes the deny for that role, but the implicit deny from the SCP’s default effect remains for all others. A common trap is confusing SCP allow lists with IAM allow policies: SCPs cannot grant permissions, only filter them. Remember the mnemonic “SCP: Set Ceilings, not Permissions”—the SCP’s deny action at the root OU still applies to the role because the SCP’s default stance is to deny everything not explicitly allowed, and the role’s IAM policy cannot override that boundary.

ANS-C01 Network Security, Compliance and Governance Practice Question

This ANS-C01 practice question tests your understanding of network security, compliance and governance. 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 runs a multi-account AWS environment using AWS Organizations. The security team wants to enforce that all S3 buckets across all accounts are encrypted with AWS KMS and that bucket policies restrict access to specific IAM roles. They have created an SCP that denies s3:PutBucketPolicy unless the bucket is encrypted with KMS (using a condition) and restricts the PutBucketPolicy action to a specific role. After applying the SCP, the development team reports that they cannot update bucket policies even when using the allowed role. The SCP is attached to the root OU. The allowed role is in the dev account and has full S3 permissions via an IAM policy. What is the most likely reason for the failure?

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.

Question 1hardmultiple choice

Full question →

A
The SCP denies s3:PutBucketPolicy for all principals except the allowed role, but the SCP is applied at the root OU and affects all accounts, so the allowed role is still denied because SCPs are deny-by-default and the allow list in the SCP does not override the implicit deny.
SCPs are deny-by-default. An SCP that denies an action unless a specific role is used effectively denies all other principals. But if the SCP has an Allow effect for the specific role, it still does not grant permission; it only removes the deny. However, the issue is that the SCP likely has a Deny statement with a condition that the role should not be denied, but if the condition is not met, the deny applies. The stem suggests the SCP restricts PutBucketPolicy to a specific role; if the SCP is written as a Deny for all principals except that role, it works only if the role ARN matches. The most common mistake is that the SCP uses a NotPrincipal element incorrectly, causing the deny to apply to everyone.
B
The SCP must be applied to the dev account specifically, not the root OU, because SCPs attached to OUs do not affect member accounts unless explicitly inherited.
Why wrong: SCPs attached to the root OU apply to all accounts in the organization. Inheritance is automatic.
C
The SCP condition key for KMS encryption is incorrect because the s3:PutBucketPolicy action does not support condition keys for encryption.
Why wrong: S3 actions support condition keys like s3:x-amz-server-side-encryption-aws-kms-key-id, but PutBucketPolicy does not have a condition key for encryption. However, the SCP could still evaluate conditions based on request parameters, but the condition might be invalid, causing denial.
D
The IAM policy attached to the allowed role does not include s3:PutBucketPolicy permission, even though it has full S3 access.
Why wrong: Full S3 access includes s3:PutBucketPolicy. If the IAM policy has S3 full access, it includes that action.

Full breakdown with real-world context →

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

✓

The SCP denies s3:PutBucketPolicy for all principals except the allowed role, but the SCP is applied at the root OU and affects all accounts, so the allowed role is still denied because SCPs are deny-by-default and the allow list in the SCP does not override the implicit deny.

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.

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.

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

✓
The SCP denies s3:PutBucketPolicy for all principals except the allowed role, but the SCP is applied at the root OU and affects all accounts, so the allowed role is still denied because SCPs are deny-by-default and the allow list in the SCP does not override the implicit deny.
Why this is correct
SCPs are deny-by-default. An SCP that denies an action unless a specific role is used effectively denies all other principals. But if the SCP has an Allow effect for the specific role, it still does not grant permission; it only removes the deny. However, the issue is that the SCP likely has a Deny statement with a condition that the role should not be denied, but if the condition is not met, the deny applies. The stem suggests the SCP restricts PutBucketPolicy to a specific role; if the SCP is written as a Deny for all principals except that role, it works only if the role ARN matches. The most common mistake is that the SCP uses a NotPrincipal element incorrectly, causing the deny to apply to everyone.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Standard ACLs match source addresses.
✗
The SCP must be applied to the dev account specifically, not the root OU, because SCPs attached to OUs do not affect member accounts unless explicitly inherited.
Why it's wrong here
SCPs attached to the root OU apply to all accounts in the organization. Inheritance is automatic.
✗
The SCP condition key for KMS encryption is incorrect because the s3:PutBucketPolicy action does not support condition keys for encryption.
Why it's wrong here
S3 actions support condition keys like s3:x-amz-server-side-encryption-aws-kms-key-id, but PutBucketPolicy does not have a condition key for encryption. However, the SCP could still evaluate conditions based on request parameters, but the condition might be invalid, causing denial.
✗
The IAM policy attached to the allowed role does not include s3:PutBucketPolicy permission, even though it has full S3 access.
Why it's wrong here
Full S3 access includes s3:PutBucketPolicy. If the IAM policy has S3 full access, it includes that action.

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 ANS-C01 ACL questions on filtering logic and placement.

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FAQ

Questions learners often ask

What does this ANS-C01 question test?

Network Security, Compliance and Governance — This question tests Network Security, Compliance and Governance — Standard ACLs match source addresses..

What is the correct answer to this question?

The correct answer is: The SCP denies s3:PutBucketPolicy for all principals except the allowed role, but the SCP is applied at the root OU and affects all accounts, so the allowed role is still denied because SCPs are deny-by-default and the allow list in the SCP does not override the implicit deny.

What should I do if I get this ANS-C01 question wrong?

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.

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