The answer is that the Phase 2 configuration is using 10.0.1.0/24 as the local subnet and 192.168.1.0/24 as the remote subnet. This is correct because the `diagnose vpn ike config list` output displays the IKE Phase 2 selectors, where `src` always indicates the local protected subnet and `dst` indicates the remote protected subnet that will be encrypted through the VPN tunnel. On the Fortinet NSE 4 Network Security Professional NSE4 exam, this command tests your ability to interpret live VPN configuration without relying on the GUI, often appearing in troubleshooting scenarios where a tunnel is up but traffic isn't passing. A common trap is confusing `src` and `dst` with source and destination IP addresses of individual packets, but remember that in Phase 2 selectors, these refer to entire subnets, not host traffic. For a quick memory tip, think "src = site (local), dst = distant (remote)" to keep the mapping straight.
NSE4 Authentication and VPN Practice Question
This NSE4 practice question tests your understanding of authentication and vpn. 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.
You run the following CLI command on a FortiGate: 'diagnose vpn ike config list'. The output includes: 'src 10.0.1.0/24:0 dst 192.168.1.0/24:0'. What does this indicate?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The Phase 2 configuration is using 10.0.1.0/24 as local subnet and 192.168.1.0/24 as remote subnet
The command shows IKE configuration for Phase 2 selectors. The 'src' and 'dst' represent the local and remote subnets that will be protected by the VPN tunnel.
Key principle: Count usable hosts — not total addresses — and remember that the network and broadcast addresses are not available to hosts in standard IPv4 subnets.
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 firewall policy is allowing traffic from 10.0.1.0/24 to 192.168.1.0/24
Why it's wrong here
The command shows IKE config, not firewall policy.
✓
The Phase 2 configuration is using 10.0.1.0/24 as local subnet and 192.168.1.0/24 as remote subnet
Why this is correct
Phase 2 selectors define the traffic to be encrypted.
The tunnel is in dial-up mode with dynamic remote subnet
Why it's wrong here
Dial-up would show 0.0.0.0/0 or similar.
Common exam traps
Common exam trap: usable hosts are not the same as total addresses
Subnetting questions often tempt you into counting all addresses. In normal IPv4 subnets, the network and broadcast addresses are not usable host addresses.
Trap categories for this question
Similar concept trap
Dial-up would show 0.0.0.0/0 or similar.
Command / output trap
The command shows IKE config, not firewall policy.
Detailed technical explanation
How to think about this question
Subnetting questions test whether you can identify the network, broadcast address, usable range, mask and correct subnet. Slow down enough to calculate the block size correctly.
KKey Concepts to Remember
CIDR notation defines the prefix length.
Block size helps identify subnet boundaries.
Network and broadcast addresses are not usable hosts in normal IPv4 subnets.
The required host count determines the smallest suitable subnet.
TExam Day Tips
→Write the block size before choosing the subnet.
→Check whether the question asks for hosts, subnets or a specific address range.
→Do not confuse /24, /25, /26 and /27 host counts.
Key takeaway
Count usable hosts — not total addresses — and remember that the network and broadcast addresses are not available to hosts in standard IPv4 subnets.
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.
Review block sizes, usable host formulas (2^n − 2), and how to find network and broadcast addresses for /24 through /30. Then practise related NSE4 subnetting questions on CIDR, address ranges, and subnet selection.
Authentication and VPN — This question tests Authentication and VPN — CIDR notation defines the prefix length..
What is the correct answer to this question?
The correct answer is: The Phase 2 configuration is using 10.0.1.0/24 as local subnet and 192.168.1.0/24 as remote subnet — The command shows IKE configuration for Phase 2 selectors. The 'src' and 'dst' represent the local and remote subnets that will be protected by the VPN tunnel.
What should I do if I get this NSE4 question wrong?
Review block sizes, usable host formulas (2^n − 2), and how to find network and broadcast addresses for /24 through /30. Then practise related NSE4 subnetting questions on CIDR, address ranges, and subnet selection.
What is the key concept behind this question?
CIDR notation defines the prefix length.
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This NSE4 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 NSE4 exam.
Question Discussion
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