156-215.81.20 VPN Basics Practice Question
An administrator is configuring a Site-to-Site VPN between two Check Point gateways. What is the primary purpose of the Phase 1 IKE negotiation in this tunnel setup?
⚠ Common exam trap
Candidates often select 'Encrypting user traffic' as the purpose of Phase 1. This is incorrect; Phase 1 is strictly for the control plane and establishing the IKE SA.
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
✓
To establish a secure, authenticated channel for the negotiation of Phase 2 parameters.
Phase 1 IKE negotiation is essential for establishing a secure, authenticated channel between security gateways before actual data transmission begins. It negotiates the IKE SA, which protects subsequent control-plane traffic. By establishing mutual authentication and a shared secret key via Diffie-Hellman, the gateways ensure that the subsequent Phase 2 Quick Mode exchanges are encrypted and protected from interception, forming the foundation for a reliable and secure IPsec VPN tunnel.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
To negotiate the encryption and authentication algorithms for the actual user data traffic.
Why it's wrong here
Encryption and authentication algorithms for user data, known as the Encapsulating Security Payload or Authentication Header, are negotiated during Phase 2 Quick Mode, not Phase 1. Phase 1 is strictly concerned with establishing the management channel to protect the tunnel-building process itself.
- ✗
To perform Dead Peer Detection to ensure the remote peer is still active.
Why it's wrong here
Dead Peer Detection is a mechanism used to verify that the remote VPN peer is reachable after the tunnel is established. It is an independent feature or a post-negotiation monitoring tool, not a functional component of the initial Phase 1 IKE negotiation process.
- ✓
To establish a secure, authenticated channel for the negotiation of Phase 2 parameters.
Why this is correct
Phase 1 creates the IKE SA, which provides a secure control channel to protect the subsequent Phase 2 Quick Mode exchanges. This protects the sensitive parameters, such as the encryption keys and security associations intended for the actual user-plane data traffic, from being exposed.
- ✗
To define the interesting traffic that will be permitted through the VPN tunnel.
Why it's wrong here
The definition of interesting traffic is typically handled by the Security Policy or VPN Community settings, which specify which source and destination IP ranges trigger the tunnel. This is a policy-based decision, not part of the IKE Phase 1 handshake protocols.
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 156-215.81.20 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 156-215.81.20 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 156-215.81.20 exam.