easyMultiple ChoiceObjective-mapped
CISSP Practice Question: A company has multiple offices connected via a WAN
A company has multiple offices connected via a WAN. They want to ensure that all traffic between offices is encrypted and authenticated. Which technology is most appropriate?
⚠ Common exam trap
ISC2 often tests the distinction between VPN technologies by presenting DMVPN as a tempting answer because it is a Cisco-specific solution for dynamic site-to-site VPNs, but the trap is that DMVPN is a framework that relies on IPsec for encryption and authentication, not a replacement for it.
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
✓
IPsec VPN
IPsec VPN is the most appropriate technology because it operates at the network layer (Layer 3) and provides both encryption and authentication for all IP traffic between sites over an untrusted WAN. It uses protocols such as ESP (Encapsulating Security Payload) for confidentiality and AH (Authentication Header) or ESP for integrity and authentication, ensuring that all inter-office traffic is protected in transit.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
MPLS
Why it's wrong here
MPLS (Multiprotocol Label Switching) is a high-performance data-carrying mechanism that directs data from one network node to the next based on short path labels, rather than complex network addresses. While efficient for routing traffic across a WAN by optimizing forwarding decisions, MPLS inherently operates at Layer 2.5 and does not provide native encryption or authentication services for data in transit. Therefore, it cannot secure communications between multiple offices on its own, requiring an overlay security solution.
- ✗
DMVPN
Why it's wrong here
DMVPN (Dynamic Multipoint VPN) is an advanced VPN architecture that leverages IPsec, NHRP (Next Hop Resolution Protocol), and mGRE (multipoint Generic Routing Encapsulation) to create a full-mesh or hub-and-spoke VPN topology dynamically. While highly effective for connecting multiple sites efficiently and securely, it is a specific, complex implementation designed for scalability and dynamic tunnel creation. It is built upon IPsec rather than being the fundamental underlying technology for basic site-to-site encryption itself.
- ✗
SSL VPN
Why it's wrong here
SSL VPNs (Secure Sockets Layer/Transport Layer Security VPNs) primarily provide secure remote access for individual users to specific applications or network resources, often via a web browser or client software. They operate at the application layer and are optimized for user-centric access rather than establishing persistent, network-wide encrypted tunnels between entire office networks. Therefore, SSL VPN is not the standard or most efficient solution for connecting multiple offices site-to-site, which typically requires network-layer encryption.
- ✓
IPsec VPN
Why this is correct
IPsec (Internet Protocol Security) is a suite of protocols that provides cryptographic security services at the IP layer, ensuring confidentiality, integrity, and authenticity of data packets. It is the industry standard for establishing secure, encrypted tunnels between networks, making it ideal for connecting multiple office locations over an untrusted WAN. IPsec VPNs utilize protocols like Authentication Header (AH) and Encapsulating Security Payload (ESP) to secure all traffic flowing between the connected sites, providing robust site-to-site connectivity.
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
Authentication
Authentication is the process of verifying that someone or something is who or what it claims to be before granting access to a system or resource.
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.
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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.