Quick Answer
The answer is a service control policy (SCP) in AWS Organizations. SCPs are the correct choice because they establish a central guardrail that prevents unauthorized CloudFormation stack set modifications across all accounts in an organization, regardless of individual IAM permissions. Unlike IAM policies, which can be overridden by a local administrator with full access, an SCP applies a deny action at the root level that cannot be bypassed, effectively blocking any user who lacks the specific IAM policy from modifying stack sets. On the AWS Certified Advanced Networking Specialty ANS-C01 exam, this concept tests your understanding of how to enforce security boundaries at scale, often appearing in scenarios where you must distinguish between resource-level controls and organization-wide governance. A common trap is confusing stack policies (which protect resources within a stack) with SCPs, or assuming AWS Config can prevent modifications when it only detects them. Memory tip: think of an SCP as a “global deny umbrella” that covers every account, making it the only tool that can truly prevent unauthorized stack set updates from any user.
This ANS-C01 practice question tests your understanding of network security, compliance and governance. 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.
A company uses AWS CloudFormation to deploy resources. The security team wants to ensure that no IAM user can modify the stack set if they are not authorized via a specific IAM policy. Which feature should be used?
AWS Config rule with remediation
Why wrong: Reacts to changes but does not prevent them.
CloudFormation stack policy
Why wrong: Protects resources from updates, not who can update.
Service control policy (SCP) in AWS Organizations
Can deny CloudFormation actions across accounts.
IAM permissions boundary
Why wrong: Sets maximum permissions but does not prevent modification by authorized users.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
Service control policy (SCP) in AWS Organizations
Option D is correct because a service control policy (SCP) can be used to deny CloudFormation actions at the organization level. Option A is wrong because stack policies protect resources within a stack, not who can update the stack. Option B is wrong because IAM policies are account-specific and can be overridden by administrators. Option C is wrong because AWS Config does not prevent modifications.
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
For each option: why learners choose it and why it is or isn't the right answer here.
AWS Config rule with remediation
Why it's wrong here
Reacts to changes but does not prevent them.
CloudFormation stack policy
Why it's wrong here
Protects resources from updates, not who can update.
Service control policy (SCP) in AWS Organizations
Why this is correct
Can deny CloudFormation actions across accounts.
Related concept
Standard ACLs match source addresses.
IAM permissions boundary
Why it's wrong here
Sets maximum permissions but does not prevent modification by authorized users.
Common exam traps
ACLs are processed top to bottom. The first matching entry wins, and an implicit deny usually exists at the end.
Detailed technical explanation
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.
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
A company's IT admin needs to give a contractor read-only access to production logs without sharing account credentials. Using role-based access control (RBAC) and temporary scoped permissions — not a permanent shared password — is the correct pattern. Questions like this test whether you can apply least-privilege access across cloud identity services.
What to study next
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
Network Security, Compliance and Governance — This question tests Network Security, Compliance and Governance — Standard ACLs match source addresses..
The correct answer is: Service control policy (SCP) in AWS Organizations — Option D is correct because a service control policy (SCP) can be used to deny CloudFormation actions at the organization level. Option A is wrong because stack policies protect resources within a stack, not who can update the stack. Option B is wrong because IAM policies are account-specific and can be overridden by administrators. Option C is wrong because AWS Config does not prevent modifications.
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.
Standard ACLs match source addresses.
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Last reviewed: Jun 20, 2026
This ANS-C01 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 ANS-C01 exam.
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