This CISSP practice question tests your understanding of communication and network security. Compare every option against the stated constraints before choosing — the best answer satisfies all requirements, not just the most obvious one. 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 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?
MPLS
Why wrong: MPLS is a label-switching technology that does not provide encryption.
DMVPN
Why wrong: DMVPN is a specific implementation of IPsec VPN but is not the most basic technology.
SSL VPN
Why wrong: SSL VPN is designed for remote user access, not site-to-site.
IPsec VPN
IPsec VPN is the standard for site-to-site encryption and authentication.
Answer choices
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.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
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 is a label-switching technology that does not provide encryption.
DMVPN
SSL VPN
IPsec VPN
Common exam traps
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.
Detailed technical explanation
IPsec VPNs use IKE (Internet Key Exchange) for key management, typically with IKEv2 (RFC 7296) for improved security and mobility, and can operate in tunnel mode (encapsulating entire IP packets) or transport mode (encrypting only the payload). In a site-to-site scenario, tunnel mode is used, where each office's VPN gateway encrypts all outbound traffic and decrypts inbound traffic, providing end-to-end security across the WAN. A real-world consideration is that IPsec can be impacted by NAT traversal issues, requiring UDP encapsulation (RFC 3948) to pass through NAT devices.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
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.
What to study next
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FAQ
Communication and Network Security — This question tests Communication and Network Security — Read the scenario before looking for a memorised answer..
The correct answer is: 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.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 30, 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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