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.
A remote user needs to securely connect to the corporate network over the internet. Which protocol provides both encryption and authentication?
L2TP
Why wrong: L2TP is a tunneling protocol; it does not provide encryption by itself.
PPTP
Why wrong: PPTP is outdated and insecure.
SSL
Why wrong: SSL is used for secure web connections, not typically for VPNs.
IPsec
IPsec provides encryption and authentication for VPNs.
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
IPsec is the correct answer because it is a suite of protocols (AH and ESP) that provides both encryption (confidentiality) and authentication (integrity and origin verification) at the network layer. It operates in either transport or tunnel mode, making it suitable for secure site-to-site or remote-access VPNs over the internet.
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.
L2TP
Why it's wrong here
L2TP is a tunneling protocol; it does not provide encryption by itself.
PPTP
Why it's wrong here
PPTP is outdated and insecure.
SSL
Why it's wrong here
SSL is used for secure web connections, not typically for VPNs.
IPsec
Why this is correct
IPsec provides encryption and authentication for VPNs.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
The trap here is that candidates often confuse L2TP or PPTP as providing encryption, when in fact L2TP requires IPsec for security and PPTP is deprecated due to weak encryption and authentication flaws.
Detailed technical explanation
IPsec uses the Internet Key Exchange (IKE) protocol (RFC 7296) to negotiate security associations (SAs) and authenticate peers using pre-shared keys or certificates. In tunnel mode, the entire original IP packet is encapsulated and encrypted, adding a new IP header, which is critical for protecting traffic between subnets across the internet. A subtle behavior is that IPsec can be configured with ESP (Encapsulating Security Payload) to provide both encryption and authentication, while AH (Authentication Header) only provides authentication without encryption.
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
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
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 — IPsec is the correct answer because it is a suite of protocols (AH and ESP) that provides both encryption (confidentiality) and authentication (integrity and origin verification) at the network layer. It operates in either transport or tunnel mode, making it suitable for secure site-to-site or remote-access VPNs over the internet.
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 24, 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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