156-315.81.20 Advanced VPN Design Practice Question
Which mechanism ensures that a VPN tunnel remains active even if there is no traffic traversing it?
⚠ Common exam trap
Test-takers mistakenly select dynamic VPN options or dead peer detection features, confusing troubleshooting tools with the active mechanism that keeps idle tunnels alive.
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
✓
Permanent Tunnels.
Permanent Tunnels ensure that the IKE/IPsec tunnels are maintained regardless of traffic flow. This is vital for monitoring and ensuring that the tunnel is ready when a connection is initiated, preventing the delay associated with tunnel negotiation. In enterprise environments, this is often necessary for persistent applications or monitoring tools that require constant connectivity without the timeout overhead of dynamic tunnels.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Dead Peer Detection (DPD).
Why it's wrong here
Dead Peer Detection is used to verify that the remote peer is still reachable, but it does not proactively keep the tunnel up. DPD sends heartbeat packets only when the tunnel is active or as a trigger to tear down an unresponsive tunnel, rather than keeping an idle tunnel alive.
- ✓
Permanent Tunnels.
Why this is correct
Permanent Tunnels is a Check Point feature that instructs the gateway to maintain the VPN tunnel even when no traffic is passing through it. This ensures that the tunnel is always ready to transmit data, reducing the latency caused by the IKE negotiation process during the initial connection request.
- ✗
IKE Keep-Alive timers.
Why it's wrong here
IKE Keep-Alive timers are related to the re-keying process. While they ensure that keys are updated periodically, they do not manage the 'up' or 'down' state of the tunnel based on traffic flow. Relying on re-keying alone will not prevent a tunnel from timing out during prolonged idle periods.
- ✗
VPN Monitoring status check.
Why it's wrong here
VPN Monitoring is a diagnostic and visibility tool that provides status updates and performance data. It observes the state of the tunnel but does not actively control the tunnel's state or force it to remain active. It is a passive observer of the underlying IKE and IPsec processes.
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.
About these practice questions
One of 210 original 156-315.81.20 practice questions on Courseiva, each with a full explanation and wrong-answer analysis — not exam dumps or protected exam content. 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 Check Point exam blueprint
This 156-315.81.20 practice question is part of Courseiva's free Check Point 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 156-315.81.20 exam.