- A
Packet filter firewall
Packet filter firewalls are stateless and filter based on L3/L4 headers only.
- B
Next-generation firewall
Why wrong: NGFWs include deep packet inspection and application awareness beyond simple header filtering.
- C
Stateful inspection firewall
Why wrong: Stateful inspection tracks the state of active connections, which is not described here.
- D
Application proxy firewall
Why wrong: Application proxy inspects Layer 7 application data, not just headers.
Question 676 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 network administrator is configuring a firewall that examines the source and destination IP addresses, port numbers, and protocol (TCP/UDP) of each packet without considering the state of the connection. Which type of firewall is being deployed?
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 Layer 3 (Network) and Layer 4 (Transport) of the OSI model, making decisions based solely on static header fields such as source/destination IP addresses, port numbers, and protocol type (TCP/UDP). It does not track connection state or session context, which matches the description of examining each packet independently. This is the defining characteristic of a stateless packet filter, as opposed to stateful or application-layer 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.
- ✓
Packet filter firewall
Why this is correct
Packet filter firewalls are stateless and filter based on L3/L4 headers only.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Next-generation firewall
Why it's wrong here
NGFWs include deep packet inspection and application awareness beyond simple header filtering.
- ✗
Stateful inspection firewall
Why it's wrong here
Stateful inspection tracks the state of active connections, which is not described here.
- ✗
Application proxy firewall
Why it's wrong here
Application proxy inspects Layer 7 application data, not just headers.
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/port/protocol, but the key differentiator is the lack of connection state tracking, which the question explicitly states by saying 'without considering the state of the connection.'
Detailed technical explanation
How to think about this question
Stateless packet filters use Access Control Lists (ACLs) that are evaluated per-packet without memory of prior packets; for example, a rule allowing inbound TCP port 80 will permit any packet with that destination port, even if it is a spoofed SYN or part of a malformed connection. This makes them vulnerable to IP fragmentation attacks (e.g., tiny fragment attacks) where header fields are split across fragments, bypassing the filter. In contrast, stateful firewalls track the TCP sequence and acknowledgment numbers to ensure packets belong to an established session, as defined in RFC 793.
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.
Visual reference
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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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 Layer 3 (Network) and Layer 4 (Transport) of the OSI model, making decisions based solely on static header fields such as source/destination IP addresses, port numbers, and protocol type (TCP/UDP). It does not track connection state or session context, which matches the description of examining each packet independently. This is the defining characteristic of a stateless packet filter, as opposed to stateful or application-layer 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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