156-215.81.20 VPN Basics Practice Question
What is the difference between 'Main Mode' and 'Aggressive Mode' in IKE Phase 1?
⚠ Common exam trap
Candidates often confuse the speed benefits of Aggressive Mode with its security implications, incorrectly assuming that faster negotiation implies better protection for the peer's identity during the exchange.
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
✓
Main Mode protects peer identity
Main Mode provides identity protection by encrypting the exchange and hiding the gateway's identity until after the tunnel is established. Aggressive Mode is faster but sends the peer's ID in cleartext, which is less secure but useful in scenarios where the dynamic IP of a remote client makes Main Mode difficult to negotiate. Choosing between them involves balancing security posture against connection speed and network compatibility.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Main Mode is faster than Aggressive
Why it's wrong here
Main Mode is actually slower because it involves a six-packet exchange to ensure secure identity verification. Aggressive Mode is significantly faster as it completes the handshake in three packets, which is why it is preferred for remote access with dynamic IPs.
- ✗
Aggressive Mode is more secure than Main
Why it's wrong here
Aggressive Mode is inherently less secure than Main Mode because it exposes the gateway's identity in the initial, unencrypted packets. Main Mode protects the identity of both peers by performing the exchange inside an encrypted channel, making it the preferred choice for site-to-site tunnels.
- ✓
Main Mode protects peer identity
Why this is correct
Main Mode ensures that the identities of the VPN peers are not revealed during the initial handshake, as the authentication is performed within an encrypted session. This provides a higher level of privacy and security compared to the unencrypted exchanges found in Aggressive Mode.
- ✗
Aggressive Mode supports more DH groups
Why it's wrong here
The support for Diffie-Hellman groups is defined by the security policy and the capability of the hardware, not by the IKE mode being used. Both modes can support the same range of DH groups, so this is not a differentiator between them.
About these practice questions
Courseiva writes every 156-215.81.20 question from scratch — 210 in total, each with an explanation and a wrong-answer breakdown. None are copied from real exams or dumps. 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.