The answer is that the phase2 src-subnet includes the tunnel interface IP, which is the most likely problem with this configuration. This is because the phase2 selector defines the traffic that will be encrypted and sent through the IPsec tunnel, and when the src-subnet is set to 10.0.1.0/30, it encompasses the tunnel interface IP 10.0.1.1/30 itself. Including the tunnel IP in the selector can cause routing loops or prevent the tunnel from establishing, as the tunnel interface is meant for routing encapsulated traffic, not for being part of the protected subnet. On the Fortinet NSE 7 Advanced Security NSE7 exam, this tests your understanding of IPsec phase2 selectors and the critical distinction between tunnel interfaces and protected internal networks. A common trap is confusing the tunnel subnet with the actual source network behind the FortiGate; the correct src-subnet should be the internal LAN, not the point-to-point tunnel link. Memory tip: "Keep the tunnel IP out of the selector—it's the road, not the destination."
NSE7 Advanced VPN and Zero Trust Practice Question
This NSE7 practice question tests your understanding of advanced vpn and zero trust. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
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
end
Refer 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?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "most likely"
Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
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
end
A
The phase2 src-subnet includes the tunnel interface IP
The tunnel interface IP (10.0.1.1) is inside the src-subnet (10.0.1.0/30), which is incorrect. The src-subnet should be the local LAN subnet, not the tunnel subnet.
B
The remote gateway is set to a static IP but the peer might be dynamic
Why wrong: The remote-gw is set to 203.0.113.1, which is a static IP; no indication of dynamic.
C
The tunnel interface is missing the 'ip' command
Why wrong: The IP is set; DHCP is not used in this config.
D
The phase2 dst-subnet overlaps with the remote gateway
Why wrong: The dst-subnet is 10.0.2.0/30, which is different from the remote gateway 203.0.113.1.
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 IPsecVPN 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.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
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 tunnel interface IP (10.0.1.1) is inside the src-subnet (10.0.1.0/30), which is incorrect. The src-subnet should be the local LAN subnet, not the tunnel subnet.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
The remote gateway is set to a static IP but the peer might be dynamic
Why it's wrong here
The remote-gw is set to 203.0.113.1, which is a static IP; no indication of dynamic.
The phase2 dst-subnet overlaps with the remote gateway
Why it's wrong here
The dst-subnet is 10.0.2.0/30, which is different from the remote gateway 203.0.113.1.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often 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.
Detailed technical explanation
How to think about this question
In IPsec VPNs, the phase2 selectors define which traffic is encrypted and sent over the tunnel. The tunnel interface IP is used for routing and should not be part of the proxy IDs because the tunnel itself is the encapsulation layer; including it can cause the FortiGate to attempt to encrypt traffic destined for its own tunnel interface, leading to a routing loop. In FortiOS, the phase2 src-subnet should typically be the local private subnet (e.g., 192.168.1.0/24), not the tunnel subnet (10.0.1.0/30), to avoid this misconfiguration.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A network engineer segments a warehouse floor into three subnets: 20 scanners, 5 printers, and 2 management hosts. Picking the wrong mask wastes addresses or leaves too few usable hosts. Exam questions test whether you can apply CIDR notation, calculate block size, and identify the correct usable-host range for a given prefix.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Advanced VPN and Zero Trust — This question tests Advanced VPN and Zero Trust — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: 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.
What should I do if I get this NSE7 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Are there clue words in this question I should notice?
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
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.
Question Discussion
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
Sign in to join the discussion.