- A
L2TP/IPsec
Why wrong: L2TP/IPsec combines L2TP with IPsec; it is more complex and not optimized for ECC or low overhead.
- B
IPsec with ESP in tunnel mode
Why wrong: IPsec can use ECC but is more complex and has higher overhead; it does not natively mandate forward secrecy.
- C
WireGuard
WireGuard uses ECC, provides forward secrecy, and has a lightweight design.
- D
SSL/TLS VPN
Why wrong: SSL/TLS VPNs can provide forward secrecy but typically have higher overhead and may not use ECC as a core component.
Question 164 of 1,000
CISSP Communication and Network Security Practice Question
This CISSP practice question tests your understanding of communication and network security. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. 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 recommending a VPN protocol for remote access. The requirements are: strong encryption, perfect forward secrecy, use of elliptic curve cryptography, and minimal overhead. Which VPN protocol best meets these requirements?
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
✓
WireGuard
WireGuard is the correct choice because it uses modern elliptic curve cryptography (Curve25519) for key exchange, provides perfect forward secrecy by default through ephemeral session keys, and has minimal overhead due to its streamlined codebase (roughly 4,000 lines of code) and lack of stateful configuration. It operates over UDP with a simple cryptographic design that meets all specified requirements without the complexity of IPsec or SSL/TLS.
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.
- ✗
L2TP/IPsec
Why it's wrong here
L2TP/IPsec combines L2TP with IPsec; it is more complex and not optimized for ECC or low overhead.
- ✗
IPsec with ESP in tunnel mode
Why it's wrong here
IPsec can use ECC but is more complex and has higher overhead; it does not natively mandate forward secrecy.
- ✓
WireGuard
Why this is correct
WireGuard uses ECC, provides forward secrecy, and has a lightweight design.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
SSL/TLS VPN
Why it's wrong here
SSL/TLS VPNs can provide forward secrecy but typically have higher overhead and may not use ECC as a core component.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often default to IPsec (options A or B) as the 'standard' VPN protocol, overlooking that WireGuard is a modern, lightweight alternative that natively integrates elliptic curve cryptography and PFS with minimal overhead, which IPsec does not guarantee without additional configuration.
Detailed technical explanation
How to think about this question
WireGuard uses the Noise protocol framework for key exchange, specifically the Noise_IK handshake, which combines Curve25519 for ECDH, ChaCha20 for symmetric encryption, and Poly1305 for authentication, all designed for minimal overhead. Its perfect forward secrecy is achieved by generating ephemeral session keys for each connection, ensuring that compromise of a long-term private key does not expose past traffic. In real-world scenarios, WireGuard's simplicity reduces attack surface and CPU usage, making it ideal for low-power devices like IoT or mobile clients.
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.
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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: WireGuard — WireGuard is the correct choice because it uses modern elliptic curve cryptography (Curve25519) for key exchange, provides perfect forward secrecy by default through ephemeral session keys, and has minimal overhead due to its streamlined codebase (roughly 4,000 lines of code) and lack of stateful configuration. It operates over UDP with a simple cryptographic design that meets all specified requirements without the complexity of IPsec or SSL/TLS.
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.
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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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