NSE7 Advanced VPN and Zero Trust Practice Question
Exhibit
Refer to the exhibit.
config system interface
edit "to_remote"
set vdom "root"
set ip 10.0.1.1 255.255.255.252
set type tunnel
set remote-ip 10.0.1.2 255.255.255.252
set interface "wan1"
next
end
config vpn ipsec phase1
edit "vpn_1"
set interface "wan1"
set peertype any
set net-device enable
set proposal aes256-sha256
set dhgrp 14
set remote-gw 203.0.113.1
set psksecret ********
next
end
config vpn ipsec phase2
edit "vpn_2"
set phase1name "vpn_1"
set proposal aes256-sha256
set src-subnet 10.0.1.0 255.255.255.252
set dst-subnet 10.0.2.0 255.255.255.252
next
endRefer to the exhibit. A tunnel interface is configured with IP 10.0.1.1/30 and remote-ip 10.0.1.2/30. The phase2 defines src-subnet as 10.0.1.0/30 and dst-subnet as 10.0.2.0/30. What is the most likely problem with this configuration?
⚠ Common exam trap
Test-takers frequently confuse the tunnel interface subnet with the protected local subnet, assuming the phase2 selectors should match the tunnel IPs, when in fact they must specify the actual internal networks behind the VPN gateways.
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
✓
The phase2 src-subnet includes the tunnel interface IP
The phase2 src-subnet is set to 10.0.1.0/30, which includes the tunnel interface IP 10.0.1.1/30. In IPsec VPN configurations, the phase2 selector must not include the tunnel interface IP itself because the tunnel interface is used for routing encapsulated traffic; including it can cause routing loops or prevent the tunnel from establishing correctly. The correct src-subnet should be the protected internal network behind the FortiGate, not the tunnel subnet.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
The phase2 src-subnet includes the tunnel interface IP
Why this is correct
The phase2 selector 10.0.1.0/30 overlaps the tunnel interface subnet, so traffic sourced from 10.0.1.1 matches the encryption domain and is routed into the tunnel rather than reaching the remote gateway. FortiGate requires selectors distinct from the tunnel IP range to avoid this routing conflict.
- ✗
The remote gateway is set to a static IP but the peer might be dynamic
Why it's wrong here
The exhibit gives no evidence of a dynamic peer; the tunnel interface and remote-ip are both statically defined, so this misreads the configuration. It is tempting because dynamic peers are common in VPN troubleshooting, and it would be correct if the remote gateway were configured as 0.0.0.0 with a dial-up phase1.
- ✗
The tunnel interface is missing the 'ip' command
Why it's wrong here
The tunnel interface already carries 10.0.1.1/30, so the ip command is present and not missing. It is tempting because an unaddressed tunnel interface does break routing, and it would be correct if the exhibit showed only remote-ip configured with no local address assigned to the interface.
- ✗
The phase2 dst-subnet overlaps with the remote gateway
Why it's wrong here
The remote gateway is 10.0.1.2/30, while the phase2 destination selector is 10.0.2.0/30, so no overlap exists between them. It is tempting because overlapping selectors genuinely break phase2 negotiation, and it would be correct if dst-subnet were 10.0.1.0/30, matching the tunnel subnet.
Visual reference
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.
Go deeper
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This NSE7 practice question is part of Courseiva's free Fortinet 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 NSE7 exam.