hardMultiple ChoiceObjective-mapped
SSCP Practice Question: Is designing a secure WAN link between two…
A network engineer is designing a secure WAN link between two offices using IPsec VPN. The company requires encryption of all traffic, authentication of both endpoints, and protection against replay attacks. Which combination of IPsec protocols and modes should be used?
⚠ Common exam trap
A common mix-up: candidates confuse AH with ESP, assuming AH provides encryption, or they incorrectly choose transport mode for site-to-site VPNs because they focus on endpoint authentication rather than the need to encapsulate the entire original packet for network-to-network communication.
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
✓
ESP in tunnel mode
ESP in tunnel mode encrypts and authenticates the entire original IP packet, providing confidentiality, integrity, and authentication for the entire payload. It also includes sequence numbers to protect against replay attacks, making it the correct choice for a secure WAN link between two offices.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
AH in tunnel mode
Why it's wrong here
AH provides authentication but no encryption, failing the encryption requirement.
- ✗
AH in transport mode
Why it's wrong here
AH lacks encryption and transport mode is inappropriate for site-to-site.
- ✓
ESP in tunnel mode
Why this is correct
ESP in tunnel mode encrypts and authenticates the entire packet, suitable for site-to-site VPNs.
- ✗
ESP in transport mode
Why it's wrong here
Transport mode is for end-to-end communication, not for gateway-to-gateway VPNs.
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
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This SSCP 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 SSCP exam.