LPIC-2 System Security Practice Question
To ensure that OpenVPN clients authenticate the server, which configuration directive should be present on the client side?
⚠ Common exam trap
Many exam-takers confuse `tls-auth` (which provides a shared secret for control channel authentication) with certificate-based server authentication, mistakenly thinking it verifies the server's identity, when in fact only the `ca` directive enables proper PKI-based server validation.
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
✓
ca
The `ca` directive on the client side specifies the Certificate Authority (CA) certificate file that the client uses to verify the server's certificate during the TLS handshake. This ensures the client authenticates the server's identity, preventing man-in-the-middle attacks. Without this, the client cannot validate that it is connecting to a trusted OpenVPN server.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
tls-verify
Why it's wrong here
tls-verify is a script to verify the server certificate, but ca is the standard directive.
- ✗
tls-auth
Why it's wrong here
tls-auth provides a pre-shared key for additional authentication, not server certificate verification.
- ✓
ca
Why this is correct
ca points to the CA certificate file that verifies the server's certificate.
- ✗
cert
Why it's wrong here
cert is the client's own certificate, used for client authentication.
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 LPIC-2 practice question is part of Courseiva's free LPI 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 LPIC-2 exam.