- A
PPTP
PPTP uses MS-CHAPv2 and lacks IKE, making it vulnerable.
- B
IPsec with IKEv2
Why wrong: IPsec uses IKE for key exchange and can use various authentication methods, not MS-CHAPv2.
- C
SSL/TLS VPN
Why wrong: SSL/TLS VPNs use certificate or password-based authentication, not MS-CHAPv2.
- D
L2TP/IPsec
Why wrong: L2TP/IPsec uses IPsec for encryption and IKE for key exchange, and typically uses stronger authentication methods.
Question 602 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 consultant discovers that a legacy VPN solution uses MS-CHAPv2 for authentication and does not support IKE. The protocol is known to be vulnerable to dictionary attacks. Which VPN protocol is most likely being used?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue:
"most likely"Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
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
✓
PPTP
MS-CHAPv2 is a Microsoft proprietary authentication protocol used by PPTP (Point-to-Point Tunneling Protocol). PPTP does not support IKE (Internet Key Exchange) and relies on MS-CHAPv2, which is vulnerable to dictionary attacks due to its weak hashing and lack of mutual authentication. The combination of MS-CHAPv2 authentication and the absence of IKE support directly points to PPTP as the VPN protocol in use.
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.
- ✓
PPTP
Why this is correct
PPTP uses MS-CHAPv2 and lacks IKE, making it vulnerable.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
IPsec with IKEv2
Why it's wrong here
IPsec uses IKE for key exchange and can use various authentication methods, not MS-CHAPv2.
- ✗
SSL/TLS VPN
Why it's wrong here
SSL/TLS VPNs use certificate or password-based authentication, not MS-CHAPv2.
- ✗
L2TP/IPsec
Why it's wrong here
L2TP/IPsec uses IPsec for encryption and IKE for key exchange, and typically uses stronger authentication methods.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates may confuse L2TP/IPsec with PPTP because both can use MS-CHAPv2, but L2TP/IPsec requires IKE and typically uses IPsec for encryption, whereas PPTP does not support IKE and relies solely on MS-CHAPv2 for authentication.
Detailed technical explanation
How to think about this question
PPTP encapsulates PPP frames in IP datagrams using GRE (Generic Routing Encapsulation) and relies on MS-CHAPv2 for authentication, which uses a challenge-response mechanism with a weak 8-byte hash derived from the user's password. The vulnerability to dictionary attacks stems from the fact that an attacker can capture the challenge and response, then offline brute-force the password using tools like Asleap or Chapcrack. In real-world scenarios, legacy PPTP deployments in corporate environments are often targeted because administrators mistakenly believe MS-CHAPv2 provides adequate security, despite RFC 2548 noting its weaknesses.
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
VPN Protocol Comparison
| Protocol | Port | Encryption | Authentication | Use Case |
|---|---|---|---|---|
| IKEv2 / IPsec | UDP 500 / 4500 | AES-256 | Certificates / PSK | Site-to-site & remote access |
| SSL / TLS VPN | TCP 443 | TLS 1.3 | Certificates / MFA | Clientless remote access |
| L2TP / IPsec | UDP 1701 | AES (IPsec) | PSK / Certificates | Legacy remote access |
| WireGuard | UDP 51820 | ChaCha20 | Public keys | Modern high-performance VPN |
| PPTP | TCP 1723 | MPPE (weak) | MS-CHAPv2 | Legacy — avoid in production |
PPTP is considered insecure. IKEv2/IPsec and SSL VPN are the current recommended options.
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: PPTP — MS-CHAPv2 is a Microsoft proprietary authentication protocol used by PPTP (Point-to-Point Tunneling Protocol). PPTP does not support IKE (Internet Key Exchange) and relies on MS-CHAPv2, which is vulnerable to dictionary attacks due to its weak hashing and lack of mutual authentication. The combination of MS-CHAPv2 authentication and the absence of IKE support directly points to PPTP as the VPN protocol in use.
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.
Are there clue words in this question I should notice?
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
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.