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Advanced Networking and SD-WANeasyMultiple ChoiceObjective-mapped

NSE7 Advanced Networking and SD-WAN Practice Question

What is the purpose of BFD (Bidirectional Forwarding Detection) in a FortiGate routing configuration?

⚠ Common exam trap

Test-takers frequently confuse BFD's role in fast failure detection with routing protocol features like authentication or encryption, or mistakenly think BFD itself provides load balancing, when in fact it only monitors path liveliness and triggers convergence.

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

To detect forwarding path failures quickly

BFD (Bidirectional Forwarding Detection) provides fast failure detection for forwarding paths between two adjacent routers, independent of any routing protocol. In FortiGate configurations, BFD is used to detect link or neighbor failures in sub-second intervals (e.g., 50-100 ms), enabling rapid convergence for dynamic routing protocols like OSPF or BGP. This is critical for SD-WAN and high-availability scenarios where traditional keepalive timers (e.g., OSPF Hello/Dead intervals of 10-40 seconds) are too slow.

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

  • To encrypt routing protocol traffic

    Why it's wrong here

    BFD does not encrypt; it is a detection mechanism.

  • To detect forwarding path failures quickly

    Why this is correct

    BFD rapidly detects failures for faster convergence.

  • To authenticate routing peers

    Why it's wrong here

    Authentication is done via MD5 or SHA, not BFD.

  • To provide load balancing across multiple paths

    Why it's wrong here

    Load balancing is done by ECMP or SD-WAN.

Visual reference

R1 R2 R3 R4 10 100 10 100 OSPF picks R1→R2→R4 (cost 20) over R1→R3→R4 (cost 200)

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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.