This CCSP practice question tests your understanding of cloud security operations. 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 is deploying a multi-tier application in a public cloud and needs to restrict traffic between tiers. The web tier must only accept HTTPS from the internet, and the app tier must only accept HTTP from the web tier. Which cloud networking feature should be used to enforce this?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Network access control lists (ACLs) attached to the subnets.
Network ACLs are stateless, meaning they filter traffic based on source and destination IP addresses, ports, and protocols at the subnet level. By configuring inbound rules on the web tier subnet to allow HTTPS (TCP/443) from the internet and outbound rules to allow HTTP (TCP/80) to the app tier subnet, and inbound rules on the app tier subnet to allow HTTP only from the web tier subnet, you enforce the required traffic restrictions without maintaining session state. This stateless behavior is essential for explicitly controlling traffic between tiers in a multi-tier architecture.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✓
Network access control lists (ACLs) attached to the subnets.
Why this is correct
Network ACLs are stateless and can enforce explicit allow rules between subnets.
Related concept
Read the scenario before looking for a memorised answer.
✗
Security groups applied to each tier’s instances.
Why it's wrong here
Security groups are stateful and not designed for network-level segmentation between tiers.
✗
Internet gateway with appropriate routes.
Why it's wrong here
Internet gateway handles internet traffic, not inter-tier.
✗
VPC peering connection between tier subnets.
Why it's wrong here
VPC peering is for connecting different VPCs, not inter-tier within same VPC.
Common exam traps
Common exam trap: answer the scenario, not the keyword
ISC2 often tests the distinction between stateless (network ACLs) and stateful (security groups) filtering, and the trap here is that candidates assume security groups can enforce inter-tier traffic restrictions as effectively as ACLs, overlooking that security groups are stateful and instance-specific, not subnet-wide.
Detailed technical explanation
How to think about this question
Network ACLs operate at Layer 3/4 and are evaluated in rule-number order (lowest to highest) with an implicit deny-all at the end; each rule can specify allow or deny for a specific protocol, port range, and CIDR block. A common subtlety is that because ACLs are stateless, you must explicitly define both inbound and outbound rules for bidirectional traffic—for example, allowing ephemeral ports (1024-65535) in the outbound direction of the web tier subnet to permit return traffic from the app tier. In a real-world scenario, misconfiguring these return rules is a frequent cause of connectivity failures in multi-tier applications.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
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
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Cloud Security Operations — This question tests Cloud Security Operations — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Network access control lists (ACLs) attached to the subnets. — Network ACLs are stateless, meaning they filter traffic based on source and destination IP addresses, ports, and protocols at the subnet level. By configuring inbound rules on the web tier subnet to allow HTTPS (TCP/443) from the internet and outbound rules to allow HTTP (TCP/80) to the app tier subnet, and inbound rules on the app tier subnet to allow HTTP only from the web tier subnet, you enforce the required traffic restrictions without maintaining session state. This stateless behavior is essential for explicitly controlling traffic between tiers in a multi-tier architecture.
What should I do if I get this CCSP question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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