CISSP Communication and Network Security Practice Question
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?
⚠ Common exam trap
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.
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.
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 fails the requirement for minimal overhead because it encapsulates traffic twice—first in L2TP and then in IPsec—adding header and processing burden that the correct protocol avoids. It is tempting because IPsec itself provides strong encryption and perfect forward secrecy, making L2TP/IPsec a common choice for site-to-site VPNs where overhead is less critical than compatibility with legacy systems.
- ✗
IPsec with ESP in tunnel mode
Why it's wrong here
IPsec with ESP in tunnel mode provides strong encryption and can use elliptic curve cryptography, but it does not inherently enforce perfect forward secrecy (PFS) unless an additional key exchange protocol like IKEv2 with Diffie-Hellman is explicitly configured; the stem requires PFS as a built-in property, not an optional add-on. This option is tempting because IPsec is a mature, widely deployed standard for site-to-site VPNs and remote access, and it would be correct in a scenario where PFS is not mandated or where the engineer can manually enforce it through IKE configuration.
- ✓
WireGuard
Why this is correct
WireGuard is the superior choice due to its modern cryptographic design, which inherently incorporates elliptic curve cryptography (ECC) for efficient key exchange and strong Perfect Forward Secrecy (PFS) through its Noise protocol framework. Its extremely lightweight codebase, consisting of only a few thousand lines, significantly reduces the attack surface and contributes to its high performance and minimal overhead, making it ideal for various platforms and resource-constrained environments.
- ✗
SSL/TLS VPN
Why it's wrong here
SSL/TLS VPNs, while capable of providing Perfect Forward Secrecy (PFS) with modern TLS versions and configurations, typically suffer from higher overhead compared to more modern protocols. This overhead stems from the complexity of the TLS handshake, certificate management, and often running over TCP, which can introduce performance issues like TCP-over-TCP meltdown. Furthermore, the use of elliptic curve cryptography (ECC) is not always a default or core component across all implementations, potentially leading to less efficient or weaker cryptographic choices if not explicitly configured.
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.
Go deeper
Related to this question
Learn chapter
Security Governance and Principles
Key term
IPsec
IPsec is a suite of protocols used to secure Internet Protocol (IP) communications by encrypting and authenticating each IP packet in a data stream.
Key term
Security
Security in IT is the practice of protecting systems, networks, and data from unauthorized access, damage, or theft.
About these practice questions
Courseiva writes every CISSP question from scratch — 747 in total, each with an explanation and a wrong-answer breakdown. None are copied from real exams or dumps. Learn why practice questions differ from exam dumps →
JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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.