NSE7 Advanced Networking and SD-WAN Practice Question
A network administrator is configuring SD-WAN on a FortiGate. They have multiple WAN links and want to ensure that traffic for a critical application uses the link with the lowest latency. Which SD-WAN configuration component should be used to achieve this?
⚠ Common exam trap
Many candidates confuse 'static priority' (which is a fixed preference) with dynamic SLA-based selection, or they incorrectly assume 'spillover' or 'lowest-cost' algorithms can react to latency changes in real time.
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
✓
Performance SLA with latency threshold and SD-WAN rule using best-quality strategy
The Performance SLA monitors latency (and other metrics) against a configured threshold, and the SD-WAN rule with the 'best-quality' strategy dynamically selects the WAN link that currently has the lowest latency. This ensures the critical application traffic is steered to the optimal link based on real-time performance measurements.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Performance SLA with latency threshold and SD-WAN rule using best-quality strategy
Why this is correct
A Performance SLA actively probes each WAN link, measuring latency against the configured threshold, while the SD-WAN rule's best-quality strategy selects the member with the lowest measured latency for the critical application. This directly satisfies the requirement to route traffic over the lowest-latency link.
- ✗
SD-WAN rule with spillover load balancing
Why it's wrong here
Spillover load balancing forwards traffic to a secondary link only once the primary link's bandwidth threshold is exceeded, so link latency is never measured or compared. It suits capacity-driven overflow between unequal links, not latency-based path selection for a critical application.
- ✗
SD-WAN members with static priority
Why it's wrong here
Static priority ranks members by a fixed administrative value, so it cannot react to changing latency across the WAN links. It is tempting because priority ordering does suit failover designs, where a preferred link carries traffic until it drops. Meeting the lowest-latency requirement needs SD-WAN performance SLAs measuring each member's live latency.
- ✗
Load balancing algorithm set to lowest-cost (SLA)
Why it's wrong here
Lowest-cost (SLA) selects the member with the lowest configured cost value among those meeting the SLA targets; it does not rank members by measured latency. It fits cost-prioritised path selection where several links satisfy the same SLA.
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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.