- A
Stateless nature of ARP with no authentication
ARP does not verify the authenticity of ARP replies, making it trivial to spoof.
- B
Lack of encryption in ARP packets
Why wrong: While ARP is unencrypted, the core vulnerability is the lack of authentication, not encryption.
- C
Weakness in the IP address resolution algorithm
Why wrong: The algorithm itself is not weak; the lack of security is the issue.
- D
Use of broadcast frames for all requests
Why wrong: Broadcast is normal; the vulnerability is that replies are trusted without verification.
Question 311 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.
During a security assessment, a penetration tester successfully performs an ARP spoofing attack, redirecting traffic through their machine. This attack exploits which protocol vulnerability?
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
✓
Stateless nature of ARP with no authentication
ARP spoofing succeeds because ARP is a stateless protocol that does not authenticate or verify the legitimacy of ARP replies. Any host on a local network can send an unsolicited ARP reply (gratuitous ARP) to associate any IP address with any MAC address, allowing an attacker to redirect traffic without any validation mechanism.
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.
- ✓
Stateless nature of ARP with no authentication
Why this is correct
ARP does not verify the authenticity of ARP replies, making it trivial to spoof.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Lack of encryption in ARP packets
Why it's wrong here
While ARP is unencrypted, the core vulnerability is the lack of authentication, not encryption.
- ✗
Weakness in the IP address resolution algorithm
Why it's wrong here
The algorithm itself is not weak; the lack of security is the issue.
- ✗
Use of broadcast frames for all requests
Why it's wrong here
Broadcast is normal; the vulnerability is that replies are trusted without verification.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Cisco often tests the distinction between the stateless nature of ARP (no authentication) and the use of broadcast frames, tricking candidates into thinking the broadcast mechanism is the vulnerability rather than the lack of validation of unsolicited replies.
Detailed technical explanation
How to think about this question
ARP operates at Layer 2 of the OSI model and maintains a cache of IP-to-MAC mappings; an attacker sends a forged ARP reply that updates the victim's cache without any prior request (gratuitous ARP). This allows man-in-the-middle attacks where traffic is intercepted, and tools like arpspoof or Ettercap automate this by sending continuous spoofed replies to keep the cache poisoned. In real-world scenarios, ARP spoofing can bypass network segmentation and enable session hijacking or credential theft on switched networks.
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 developer is choosing between AES-256 (symmetric) and RSA-2048 (asymmetric) for encrypting a large file that will be sent to a partner. Symmetric encryption is fast but requires key exchange; asymmetric is slower but solves the key distribution problem. A hybrid approach — encrypt the file with AES, encrypt the AES key with RSA — is standard. Questions like this test whether you understand when each approach applies.
Quick reference
Access Control Model Comparison
| Model | Acronym | Who Controls Access? | Best For |
|---|---|---|---|
| Discretionary Access Control | DAC | Resource owner | Small teams, file shares |
| Mandatory Access Control | MAC | System / security labels | Classified govt / military |
| Role-Based Access Control | RBAC | Administrator (via roles) | Enterprise environments |
| Attribute-Based Access Control | ABAC | Policy engine (user + resource attributes) | Fine-grained, dynamic policies |
| Rule-Based Access Control | RuBAC | System rules / ACLs | Firewall rules, network ACLs |
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: Stateless nature of ARP with no authentication — ARP spoofing succeeds because ARP is a stateless protocol that does not authenticate or verify the legitimacy of ARP replies. Any host on a local network can send an unsolicited ARP reply (gratuitous ARP) to associate any IP address with any MAC address, allowing an attacker to redirect traffic without any validation mechanism.
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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