NSE7 Advanced Networking and SD-WAN Practice Question
An administrator needs to configure an SD-WAN rule that routes traffic from the guest VLAN to the Internet using the most cost-effective link. The SD-WAN zone contains three members: port1 (MPLS, cost 10), port2 (Broadband, cost 5), and port3 (LTE, cost 20). All members meet the performance SLA. Which load balancing algorithm should be used to ensure traffic uses the lowest-cost link?
⚠ Common exam trap
It's easy for candidates to confuse 'Lowest Cost' with 'Best Quality' or 'Volume', and assuming that cost is considered in those algorithms when it is not.
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
✓
Lowest Cost
The 'Lowest Cost' strategy is designed to select the member with the lowest cost that meets the SLA. In this scenario, port2 has the lowest cost, so it will be chosen as long as it meets the SLA. This ensures that guest traffic uses the most cost-effective link while still maintaining acceptable performance. The other strategies do not prioritize cost and would not meet the requirement.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Best Quality
Why it's wrong here
The 'Best Quality' strategy selects the member with the best measured quality based on SLA metrics, not the lowest cost. While it ensures good performance, it does not consider cost, so it might select a more expensive link like MPLS if it has better quality. This does not meet the requirement of using the most cost-effective link.
- ✗
Source IP
Why it's wrong here
The 'Source IP' algorithm distributes traffic based on source IP addresses, typically for session persistence. It does not consider cost or link quality. Using this algorithm would not ensure that traffic uses the lowest-cost link; it might randomly assign sessions to any member.
- ✗
Volume
Why it's wrong here
The 'Volume' algorithm distributes traffic based on bandwidth proportions, not cost. It would not necessarily select the lowest-cost link; instead, it would balance traffic across members according to their configured bandwidth. This does not meet the requirement of using the most cost-effective link.
- ✓
Lowest Cost
Why this is correct
The 'Lowest Cost' strategy selects the member with the lowest configured cost that also meets the SLA. In this scenario, port2 has the lowest cost (5), so it will be chosen, provided it meets the SLA. This directly satisfies the requirement to use the most cost-effective link while ensuring performance.
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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 Fortinet exam blueprint
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.