- A
Stateful inspection firewall
Why wrong: Stateful inspection tracks connection state, which this scenario does not.
- B
Application proxy firewall
Why wrong: Application proxy inspects application-layer data, not just IP/ports.
- C
Packet filter firewall
Packet filter is stateless and uses IP/port rules.
- D
Next-generation firewall
Why wrong: NGFW includes deep packet inspection and application awareness.
Question 30 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 engineer is configuring a firewall that makes decisions based on source/destination IP addresses and port numbers without tracking the state of connections. Which type of firewall is this?
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
✓
Packet filter firewall
A packet filter firewall operates at Layers 3 and 4 of the OSI model, making forwarding decisions solely based on static fields such as source/destination IP addresses and port numbers. It does not maintain any connection state table, meaning each packet is evaluated independently without reference to previous packets. This stateless behavior is the defining characteristic that distinguishes it from stateful inspection firewalls.
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.
- ✗
Stateful inspection firewall
Why it's wrong here
Stateful inspection tracks connection state, which this scenario does not.
- ✗
Application proxy firewall
Why it's wrong here
Application proxy inspects application-layer data, not just IP/ports.
- ✓
Packet filter firewall
Why this is correct
Packet filter is stateless and uses IP/port rules.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Next-generation firewall
Why it's wrong here
NGFW includes deep packet inspection and application awareness.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse 'stateless packet filtering' with 'stateful inspection' because both examine IP addresses and ports, but the key differentiator is the absence of connection tracking in packet filters.
Trap categories for this question
Scenario analysis trap
Stateful inspection tracks connection state, which this scenario does not.
Detailed technical explanation
How to think about this question
Packet filter firewalls typically use Access Control Lists (ACLs) configured on routers or dedicated firewall appliances, evaluating each packet against rules in sequential order. A subtle behavior is that because they lack state awareness, they cannot differentiate between a legitimate response packet and a malicious packet that spoofs a source IP and port, making them vulnerable to IP spoofing attacks. In real-world scenarios, stateless filters are often deployed at the network perimeter for simple traffic segmentation, while stateful firewalls handle more complex internal traffic.
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.
Quick reference
OSI Model Reference
| Layer | Name | PDU | Key Protocols / Devices |
|---|---|---|---|
| 7 | Application | Data | HTTP, HTTPS, DNS, SMTP, FTP, SSH |
| 6 | Presentation | Data | TLS / SSL, JPEG, ASCII encoding |
| 5 | Session | Data | NetBIOS, RPC, SIP |
| 4 | Transport | Segment / Datagram | TCP, UDP |
| 3 | Network | Packet | IP, ICMP, OSPF — Routers |
| 2 | Data Link | Frame | Ethernet, Wi-Fi, PPP — Switches, Bridges |
| 1 | Physical | Bits | Cables, NICs, Hubs, Repeaters |
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: Packet filter firewall — A packet filter firewall operates at Layers 3 and 4 of the OSI model, making forwarding decisions solely based on static fields such as source/destination IP addresses and port numbers. It does not maintain any connection state table, meaning each packet is evaluated independently without reference to previous packets. This stateless behavior is the defining characteristic that distinguishes it from stateful inspection firewalls.
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.
About these practice questions
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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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