NSE7 Advanced Networking and SD-WAN Practice Question
An administrator notices that when a BGP session goes down, failover to the backup path takes about 30 seconds. The admin wants to reduce the failover time to less than 1 second. Which technology should the administrator implement?
⚠ Common exam trap
Many exam-takers confuse BGP fast external failover (which only helps for directly connected interface flaps) with BFD (which provides sub-second detection for any failure along the path), leading them to select option A instead of D.
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
✓
Enable BFD on the BGP neighbor and the associated interface
BFD (Bidirectional Forwarding Detection) provides sub-second failure detection for BGP sessions by sending rapid hello packets independently of the BGP keepalive mechanism. By enabling BFD on both the BGP neighbor and the associated interface, the router can detect a link or neighbor failure in milliseconds (e.g., 50-300 ms), allowing BGP to converge and switch to the backup path in under 1 second, far faster than the default 30-second hold timer.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Configure BGP fast external failover
Why it's wrong here
Fast external failover uses interface state changes; it may not detect failures beyond directly connected links.
- ✗
Increase the BGP keepalive timer to 1 second
Why it's wrong here
Lowering keepalive timers can improve detection but typically not below 1 second; BFD is faster.
- ✗
Use policy-based routing with SLA monitoring
Why it's wrong here
PBR with SLA can detect failures but may not be as fast as BFD.
- ✓
Enable BFD on the BGP neighbor and the associated interface
Why this is correct
BFD provides fast failure detection (milliseconds) for routing protocols.
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JA
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.