- A
Layer 4 – Transport
Why wrong: Transport layer protocols include TCP and UDP, not ARP.
- B
Layer 3 – Network
Why wrong: ARP is not a Layer 3 protocol; IP operates at Layer 3.
- C
Layer 1 – Physical
Why wrong: ARP operates at Layer 2, not Layer 1.
- D
Layer 2 – Data Link
ARP is a Layer 2 protocol used for MAC address resolution.
Question 965 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 detects an attack where the attacker sends forged ARP messages to associate the attacker's MAC address with the IP address of the default gateway. Which OSI layer is primarily targeted by this attack?
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
✓
Layer 2 – Data Link
ARP operates at Layer 2 (Data Link) because it maps IP addresses (Layer 3) to MAC addresses (Layer 2) within a single broadcast domain. By forging ARP replies, the attacker poisons the ARP cache of hosts, causing frames destined for the default gateway to be sent to the attacker's MAC address. This directly targets the address resolution process that bridges Layer 2 and Layer 3, but the attack itself is executed at the Data Link layer.
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.
- ✗
Layer 4 – Transport
- ✗
Layer 3 – Network
Why it's wrong here
ARP is not a Layer 3 protocol; IP operates at Layer 3.
- ✗
Layer 1 – Physical
Why it's wrong here
ARP operates at Layer 2, not Layer 1.
- ✓
Layer 2 – Data Link
Why this is correct
ARP is a Layer 2 protocol used for MAC address resolution.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates see 'IP address' in the question and immediately think Layer 3 (Network), forgetting that ARP is a Layer 2 protocol that resolves Layer 3 addresses to Layer 2 addresses.
Detailed technical explanation
How to think about this question
ARP spoofing exploits the stateless nature of ARP—hosts accept unsolicited ARP replies (gratuitous ARP) without authentication, as defined in RFC 826. Tools like arpspoof (from dsniff) or Ettercap send forged ARP packets to poison the target's ARP table, enabling man-in-the-middle attacks. In a switched network, this bypasses the switch's MAC learning, forcing traffic through the attacker's interface.
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.
- →
Communication and Network Security — study guide chapter
Learn the concepts, then practise the questions
- →
Communication and Network Security practice questions
Targeted practice on this topic area only
- →
All CISSP questions
1,000 questions across all exam domains
- →
Certified Information Systems Security Professional CISSP study guide
Full concept coverage aligned to exam objectives
- →
CISSP practice test guide
How to use practice tests most effectively before exam day
Related practice questions
Related CISSP practice-question pages
Use these pages to review the topic behind this question. This is how one missed question becomes focused revision.
Security and Risk Management practice questions
Practise CISSP questions linked to Security and Risk Management.
Asset Security practice questions
Practise CISSP questions linked to Asset Security.
Security Operations practice questions
Practise CISSP questions linked to Security Operations.
Security Architecture and Engineering practice questions
Practise CISSP questions linked to Security Architecture and Engineering.
Communication and Network Security practice questions
Practise CISSP questions linked to Communication and Network Security.
Security Assessment and Testing practice questions
Practise CISSP questions linked to Security Assessment and Testing.
Software Development Security practice questions
Practise CISSP questions linked to Software Development Security.
Identity and Access Management practice questions
Practise CISSP questions linked to Identity and Access Management.
CISSP fundamentals practice questions
Practise CISSP questions linked to CISSP fundamentals.
CISSP scenario practice questions
Practise CISSP questions linked to CISSP scenario.
CISSP troubleshooting practice questions
Practise CISSP questions linked to CISSP troubleshooting.
Practice this exam
Start a free CISSP practice session
Short sessions build daily habit. Longer sessions build exam-day stamina. Try a timed session to simulate real conditions.
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: Layer 2 – Data Link — ARP operates at Layer 2 (Data Link) because it maps IP addresses (Layer 3) to MAC addresses (Layer 2) within a single broadcast domain. By forging ARP replies, the attacker poisons the ARP cache of hosts, causing frames destined for the default gateway to be sent to the attacker's MAC address. This directly targets the address resolution process that bridges Layer 2 and Layer 3, but the attack itself is executed at the Data Link layer.
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
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
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.
Question Discussion
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
Sign in to join the discussion.