SSCP Network and Communications Security Practice Question
A security administrator is configuring a VPN between two branch offices. The requirement is to encrypt the entire original IP packet and add a new IP header for routing over the internet. Which IPsec mode should be used?
⚠ Common exam trap
SSCP often tests the confusion between IKE Phase 1 modes (main/aggressive) and IPsec encapsulation modes (transport/tunnel) — candidates pick aggressive or main mode thinking they describe packet wrapping.
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
✓
Tunnel mode
Tunnel mode encapsulates the entire original IP packet — including its original header — inside a new IP packet with a new header, which is exactly what is required for site-to-site VPNs between branch offices. The new header carries the tunnel endpoint addresses so the encrypted payload can be routed across the public internet, and the original packet is restored on decapsulation.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Aggressive mode
Why it's wrong here
Aggressive mode is an ISAKMP phase-one exchange that negotiates the IKE security association faster, but it performs no packet encapsulation. It is tempting because it establishes the tunnel quickly; it would be correct when faster IKE negotiation is required and identity protection is not, not for encrypting whole packets.
- ✗
Transport mode
Why it's wrong here
Transport mode encrypts only the payload and retains the original IP header, so no new header is added for internet routing. It is tempting because it suits host-to-host traffic between two endpoints; it would be correct for protecting a single host's data, not for gateway-to-gateway branch traffic.
- ✗
Main mode
Why it's wrong here
Main mode is an ISAKMP phase-one negotiation exchange, not an IPsec encapsulation mode, so it cannot encrypt the original packet or prepend a routing header. It is tempting because it secures the initial key exchange; it would be correct when configuring how peers authenticate and establish the IKE security association before tunnel mode carries traffic.
- ✓
Tunnel mode
Why this is correct
Tunnel mode encapsulates the entire original IP packet, including its header, then prepends a new IP header for routing across the internet. Transport mode encrypts only the payload, so tunnel mode satisfies the stated requirement.
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
About these practice questions
Courseiva writes every SSCP question from scratch — 971 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 and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official ISC2 exam blueprint
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.