- A
Application proxy firewall
Why wrong: Application proxy can do this but is more complex and not necessary for simple HTTP traffic.
- B
Circuit-level gateway
Why wrong: Circuit-level gateways operate at Layer 5 and are not typically used for HTTP; they handle session layer.
- C
Stateful inspection firewall
Stateful firewalls maintain connection state and automatically allow return traffic for established connections.
- D
Packet filter firewall
Why wrong: Packet filters are stateless and require explicit rules for return traffic, which may open more ports.
Question 953 of 1,000
CISSP Communication and Network Security Practice Question
This CISSP practice question tests your understanding of communication and network security. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. 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 security analyst is configuring a firewall to allow HTTP traffic (TCP port 80) from the internet to a web server in the DMZ. The firewall should also allow return traffic from the server back to the internet. Which type of firewall is best suited to handle this traffic while maintaining security?
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
✓
Stateful inspection firewall
A stateful inspection firewall (C) is best suited because it tracks the state of active connections, allowing return traffic for established sessions (e.g., HTTP responses from the server to the internet) while blocking unsolicited inbound packets. It inspects packets at Layers 3 and 4, maintaining a state table that matches return packets to the original outbound request, ensuring only legitimate responses are permitted. This provides better security than a simple packet filter by preventing spoofed or out-of-context packets.
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.
- ✗
Application proxy firewall
Why it's wrong here
Application proxy can do this but is more complex and not necessary for simple HTTP traffic.
- ✗
Circuit-level gateway
Why it's wrong here
Circuit-level gateways operate at Layer 5 and are not typically used for HTTP; they handle session layer.
- ✓
Stateful inspection firewall
Why this is correct
Stateful firewalls maintain connection state and automatically allow return traffic for established connections.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Packet filter firewall
Why it's wrong here
Packet filters are stateless and require explicit rules for return traffic, which may open more ports.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often choose packet filter firewalls (D) because they are simpler and can technically allow HTTP traffic on port 80, but they fail to recognize that stateful inspection is required to securely handle return traffic without manually creating complex, insecure rules for ephemeral ports.
Detailed technical explanation
How to think about this question
Stateful inspection firewalls maintain a state table that records each connection's 5-tuple (source IP, destination IP, source port, destination port, protocol) and TCP sequence numbers, allowing them to validate that return packets have the correct ACK flag and sequence numbers matching the original SYN. This prevents attacks like TCP sequence prediction or blind spoofing, which a stateless packet filter cannot block. In real-world scenarios, a stateful firewall can also handle protocols like FTP that use dynamic ports by inspecting application-layer commands (e.g., PORT) to open temporary pinholes.
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 SOC analyst notices unusual lateral movement in the network at 2 AM. The IR playbook dictates: identify and contain (isolate the affected machine), then eradicate (remove the malware), then recover (restore from backup), then document. Skipping containment before eradication risks the attacker regaining access. Questions like this test the sequence and rationale of incident response phases.
Visual reference
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.
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Communication and Network Security — study guide chapter
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FAQ
Questions learners often ask
What does this CISSP question test?
Communication and Network Security — This question tests Communication and Network Security — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Stateful inspection firewall — A stateful inspection firewall (C) is best suited because it tracks the state of active connections, allowing return traffic for established sessions (e.g., HTTP responses from the server to the internet) while blocking unsolicited inbound packets. It inspects packets at Layers 3 and 4, maintaining a state table that matches return packets to the original outbound request, ensuring only legitimate responses are permitted. This provides better security than a simple packet filter by preventing spoofed or out-of-context packets.
What should I do if I get this CISSP 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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Last reviewed: Jul 4, 2026
This CISSP 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 CISSP exam.
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