156-315.81.20 Advanced VPN Design Practice Question
Which phase of the IKE negotiation establishes the secure, encrypted channel used for subsequent management and Phase 2 negotiation?
⚠ Common exam trap
Many candidates mix up Phase 1 and Phase 2, mistakenly believing that Phase 2 establishes the initial encrypted management tunnel rather than the actual data transfer tunnels protected by the Phase 1 channel.
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
✓
Phase 1 (Main/Aggressive Mode).
IKE Phase 1 is the initial phase where the gateways authenticate each other and establish a secure, encrypted tunnel. This tunnel is used exclusively for the IKE negotiation itself, including the later Phase 2 negotiation. Once the Phase 1 tunnel is up, all control information is protected from eavesdropping, which is vital for the secure exchange of IPsec keys used in Phase 2.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Phase 2 (Quick Mode).
Why it's wrong here
Phase 2, or Quick Mode, is used to negotiate the actual IPsec parameters (the data tunnel) for user traffic. It relies on the secure, pre-established Phase 1 tunnel to exchange keys. It is not responsible for creating the initial secure management channel used for the overall connection negotiation.
- ✓
Phase 1 (Main/Aggressive Mode).
Why this is correct
IKE Phase 1 (Main or Aggressive Mode) establishes the initial secure management tunnel between the two gateways. This tunnel provides the necessary confidentiality and authentication for the subsequent Phase 2 exchange. Without this secure management channel, the peers cannot safely negotiate the keys for the user data tunnel.
- ✗
Dead Peer Detection (DPD).
Why it's wrong here
DPD is a keep-alive mechanism used to verify that the remote peer is still active. It occurs after both Phase 1 and Phase 2 are completed. It does not establish the secure channel itself; it merely monitors the existing channel for connectivity loss during periods of inactivity.
- ✗
IKEv3 negotiation.
Why it's wrong here
IKEv3 does not exist in the current Check Point IKE standards. The industry standard is IKEv2, which functions similarly to IKEv1 in that it uses an initial phase to secure the control channel before negotiating the data plane. Referring to a non-existent version is technically incorrect.
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 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
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