easyMultiple Choice
Best Practice Site-to-Site VPN IPsec IKEv2
An organization wants to allow secure remote access for employees. Which protocol is most appropriate for a site-to-site VPN?
⚠ Common exam trap
Watch out — candidates often confuse SSL/TLS with site-to-site VPNs because of its common use in remote access VPNs (e.g., AnyConnect), but SSL/TLS is a transport-layer protocol designed for client-to-server connections, not for routing entire network segments.
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
IPsec is the correct choice for a site-to-site VPN because it operates at the network layer (Layer 3), providing encryption and authentication for all IP traffic between two entire networks. It supports both tunnel and transport modes, and uses protocols like ESP (Encapsulating Security Payload) and AH (Authentication Header) to ensure confidentiality, integrity, and origin authentication, making it the standard for permanent site-to-site connections.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
PPTP
Why it's wrong here
PPTP's MS-CHAPv2 authentication and RC4 encryption are cryptographically broken, so it cannot satisfy secure remote access. It is tempting because it is natively supported and trivial to configure on legacy Windows clients, making it a historical choice for basic dial-up-style VPN connectivity.
- ✗
SSL/TLS
Why it's wrong here
SSL/TLS secures individual application sessions, typically client-to-site access through a browser or VPN client, rather than encrypting traffic between two network gateways. A site-to-site VPN requires tunnel-mode IPsec, which encapsulates entire IP packets across gateways. SSL/TLS would be the right choice for remote-user access to specific web applications without a full tunnel.
- ✓
IPsec
Why this is correct
IPsec operates at the network layer, authenticating and encrypting every packet between gateways. This provides the confidentiality and integrity a site-to-site VPN requires across untrusted networks, unlike TLS, which secures individual application sessions rather than gateway-to-gateway tunnels.
- ✗
SSH
Why it's wrong here
SSH provides encrypted terminal sessions and secure file transfer to individual hosts, not encrypted tunnels between networks. It would be the right choice for administratively managing VPN gateways or transferring configuration files, but it cannot carry site-to-site traffic.
- ✗
L2TP
Why it's wrong here
L2TP supplies no encryption of its own; it must be paired with IPsec to protect traffic, so bare L2TP fails the secure-tunnel requirement. It is tempting because it handles tunnelling and is widely referenced, and L2TP/IPsec would be acceptable where IPsec is explicitly configured.
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.
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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.