This CCSP practice question tests your understanding of cloud platform and infrastructure security. 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 cloud security team is designing a defense-in-depth strategy for a web application. Which TWO of the following are effective network-level security controls? (Choose two.)
CloudTrail
Why wrong: CloudTrail is an audit service, not a network control.
Network ACLs
NACLs are stateless firewall rules at the subnet level.
IAM policies
Why wrong: IAM is identity and access management, not network-level.
Web Application Firewall (WAF)
Why wrong: WAF operates at the application layer (HTTP), not network layer.
Security groups
Security groups are stateful firewalls at the instance level.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
Network ACLs
Network ACLs (Option B) are a stateless, subnet-level firewall that filters traffic based on rules evaluating source/destination IP, protocol, and port. They operate at Layer 3/4 of the OSI model, making them an effective network-level security control for defense-in-depth by providing a first line of perimeter defense.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
CloudTrail
Why it's wrong here
CloudTrail is an audit service, not a network control.
Network ACLs
Why this is correct
NACLs are stateless firewall rules at the subnet level.
Related concept
Read the scenario before looking for a memorised answer.
IAM policies
Why it's wrong here
IAM is identity and access management, not network-level.
Web Application Firewall (WAF)
Why it's wrong here
WAF operates at the application layer (HTTP), not network layer.
Security groups
Why this is correct
Security groups are stateful firewalls at the instance level.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
The trap here is confusing application-layer controls (WAF) or identity controls (IAM) with network-layer controls, or mistaking CloudTrail (a logging service) for a network security control.
Detailed technical explanation
Network ACLs are stateless, meaning return traffic must be explicitly allowed by an outbound rule, unlike security groups which are stateful and automatically allow return traffic. In AWS, Network ACLs support numbered rules (e.g., rule 100, 200) evaluated in ascending order, and they can be used to block specific IP ranges or ports at the subnet boundary, complementing security groups for layered defense. A real-world scenario: using a Network ACL to block all inbound traffic from a known malicious CIDR block (e.g., 203.0.113.0/24) while allowing legitimate traffic through security groups.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
A security analyst at a medium-sized enterprise encounters this scenario during an investigation or architecture review. The correct answer reflects best practice for the specific threat or control described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Security exam questions test whether you can match controls to threats in context — not just recall definitions.
What to study next
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
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FAQ
Cloud Platform and Infrastructure Security — This question tests Cloud Platform and Infrastructure Security — Read the scenario before looking for a memorised answer..
The correct answer is: Network ACLs — Network ACLs (Option B) are a stateless, subnet-level firewall that filters traffic based on rules evaluating source/destination IP, protocol, and port. They operate at Layer 3/4 of the OSI model, making them an effective network-level security control for defense-in-depth by providing a first line of perimeter defense.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 24, 2026
This CCSP practice question is part of Courseiva's free ISC2 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 CCSP exam.
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