NSE7 Advanced Networking and SD-WAN Practice Question
A FortiGate with SD-WAN has two members: MPLS (port1) and Broadband (port2). The performance SLA is configured to monitor latency and packet loss. The administrator notices that after a brief outage on the MPLS link, traffic fails over to Broadband but does not fail back when MPLS recovers. What is the likely cause?
⚠ Common exam trap
Test-takers frequently confuse failback with failover triggers or SLA thresholds, assuming the issue is with detection or cost rather than the explicit failback disable setting in the SD-WAN rule.
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
✓
The SD-WAN rule for the traffic has 'set failback disable'.
The 'set failback disable' command in the SD-WAN rule prevents traffic from automatically returning to the preferred MPLS link after it recovers. By default, failback is enabled, meaning traffic will revert to the higher-priority member once the performance SLA is satisfied again. When disabled, the FortiGate keeps traffic on the backup link indefinitely, which matches the described behavior.
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 SD-WAN rule for the traffic has 'set failback disable'.
Why this is correct
The 'failback' setting controls whether traffic returns to the preferred member when it becomes healthy again. If disabled, traffic stays on the backup link.
- ✗
The SLA threshold is set too aggressively, causing the link to be considered down long after recovery.
Why it's wrong here
Thresholds affect when the link is considered down, but failback is controlled by the update frequency and SLA states.
- ✗
The Broadband link has a higher cost, so the FortiGate prefers to keep traffic there.
Why it's wrong here
Cost is not used for failback; the rule's preferred member and failback setting determine behavior.
- ✗
The SLA probe interval is longer than the outage duration, so the SLA never detected the outage.
Why it's wrong here
If the outage was brief and not detected, failover would not have occurred at all.
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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.