The answer is to create a policy route with the source address set to the specific IP and the gateway pointing to ISP1. This is correct because policy routing operates above the static routing table, allowing you to enforce a policy route for a specific source IP over ECMP without disrupting the existing equal-cost load-balancing behavior. On the Fortinet NSE 4 Network Security Professional NSE4 exam, this scenario tests your understanding of how policy-based routing can selectively override the default routing decision, a common task when managing multi-WAN setups. A frequent trap is attempting to solve this with static route metrics or administrative distances, which would break the ECMP load-balancing for all other traffic. Instead, remember that policy routes are evaluated before the routing table lookup, making them ideal for granular traffic steering. Memory tip: think of policy routing as a "VIP lane" — it lets specific traffic cut in line at the ISP1 exit, while everyone else still uses both gates.
NSE4 System and Network Administration Practice Question
This NSE4 practice question tests your understanding of system and network administration. 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.
A FortiGate is configured with two equal-cost default routes to different ISPs. The administrator notices that traffic for a specific destination is load-balanced across both links as expected. However, they want all traffic from a specific source IP to use only ISP1, while other traffic remains load-balanced. Which configuration should be applied?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Create a policy route with source address set to the specific IP and set the gateway to ISP1
Policy routing allows you to override the routing table for specific traffic based on criteria such as source IP. By creating a policy route that matches the specific source IP and sets the next-hop gateway to ISP1, you ensure that traffic from that source always uses ISP1, while all other traffic continues to be load-balanced across both equal-cost default routes. This is the most direct and flexible method for source-based path selection without altering the global routing behavior.
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.
✗
Increase the administrative distance of the ISP2 default route to 20
Why it's wrong here
This would remove the equal-cost route and make ISP2 backup, not load-balanced.
✓
Create a policy route with source address set to the specific IP and set the gateway to ISP1
Why this is correct
Policy routes match before the routing table and can steer traffic to a specific gateway.
Related concept
Read the scenario before looking for a memorised answer.
✗
Configure SD-WAN rules to steer the traffic
Why it's wrong here
SD-WAN works within an SD-WAN zone; if not using SD-WAN, policy routes are appropriate.
✗
Add a static host route for the specific source IP via ISP1
Why it's wrong here
Static routes match destination, not source.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse policy routing with static routing or administrative distance changes, mistakenly thinking that modifying route preference or adding a host route for the source IP will achieve source-based forwarding, when in fact policy routing is the only method that allows traffic selection based on source IP without affecting other traffic.
Detailed technical explanation
How to think about this question
Policy routes are evaluated before the routing table lookup, meaning they can direct traffic based on Layer 3 and Layer 4 criteria such as source IP, destination IP, or port. In FortiOS, policy routes are configured under 'Policy & Objects > Policy Routes' and are processed in order of priority; the first matching policy route is applied. This is particularly useful in multi-homed environments where you need to enforce asymmetric routing or comply with ISP-specific requirements without disrupting the default ECMP load balancing.
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 small business has 20 workstations on the 192.168.1.0/24 network and one public IP from its ISP. The router uses PAT (NAT overload) so all 20 devices share one public address using different source ports. NAT questions test whether you understand the four address terms and which direction each translation applies.
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.
System and Network Administration — This question tests System and Network Administration — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Create a policy route with source address set to the specific IP and set the gateway to ISP1 — Policy routing allows you to override the routing table for specific traffic based on criteria such as source IP. By creating a policy route that matches the specific source IP and sets the next-hop gateway to ISP1, you ensure that traffic from that source always uses ISP1, while all other traffic continues to be load-balanced across both equal-cost default routes. This is the most direct and flexible method for source-based path selection without altering the global routing behavior.
What should I do if I get this NSE4 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
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 →
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. A FortiGate is configured with two WAN links (port1 and port2) and uses ECMP routing. The administrator wants to ensure that traffic from a specific internal subnet (192.168.10.0/24) always uses port1, while all other traffic uses ECMP. Which configuration should be applied?
hard
A.Create a separate VDOM for 192.168.10.0/24 and route it through port1
✓ B.Create two static routes with equal distances to use ECMP, and add a policy route for 192.168.10.0/24 with outgoing interface port1
C.Configure a VIP to translate 192.168.10.0/24 to an IP on port1
D.Use a firewall policy to change the route based on source
Why B: Policy routes override the routing table for matching traffic, allowing you to force traffic from 192.168.10.0/24 out port1 while ECMP handles all other traffic. ECMP distributes traffic across multiple equal-cost routes, but a policy route takes precedence over the routing table for specified traffic. This meets the requirement without disrupting ECMP for other traffic.
Last reviewed: Jun 24, 2026
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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.
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