Quick Answer
The correct answer is that BFD can be configured under the interface or routing protocol to detect forwarding path failures. This is because BFD operates as a lightweight, independent protocol that establishes dedicated sessions to rapidly verify bidirectional forwarding between two devices, decoupling failure detection from the routing protocol’s own timers. On FortiGate, you enable BFD either directly on a physical or VLAN interface for static routes or SD-WAN members, or within dynamic routing protocols like OSPF or BGP to accelerate convergence. For the Fortinet NSE 7 Advanced Security NSE7 exam, this question tests your understanding that BFD is not automatic—it must be explicitly enabled—and that it is distinct from performance SLA probes, which measure latency and jitter rather than simple link liveliness. A common trap is confusing BFD’s fast detection with OSPF hello intervals; remember that BFD runs its own sub-second timers independently. Memory tip: “BFD is the heartbeat, SLA is the blood test”—one checks if the link is alive, the other checks its quality.
This NSE7 practice question tests your understanding of advanced networking and sd-wan. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
A FortiGate administrator wants to use BFD to quickly detect link failures in an SD-WAN deployment. Which statement about BFD configuration on FortiGate is correct?
BFD sessions are established automatically when OSPF neighbors form
Why wrong: BFD must be explicitly enabled under the OSPF process.
BFD uses performance SLA probes to determine link health
Why wrong: BFD uses its own control packets, not SLA probes.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
BFD can be configured under the interface or routing protocol to detect forwarding path failures
BFD (Bidirectional Forwarding Detection) is configured under the interface or routing protocol to provide fast failure detection. It is not enabled by default. Option A is incorrect because BFD must be configured. Option B is incorrect because BFD uses dedicated sessions, not sharing OSPF hello intervals. Option D is incorrect because BFD does not use performance SLA; SLAs are separate health checks.
Key principle: OSPF neighbour adjacency depends on matching area, hello/dead timers, network type, and authentication — IP reachability alone is not enough.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
BFD sessions are established automatically when OSPF neighbors form
Why it's wrong here
BFD must be explicitly enabled under the OSPF process.
BFD uses performance SLA probes to determine link health
Why it's wrong here
BFD uses its own control packets, not SLA probes.
Common exam traps
OSPF neighbour formation depends on matching areas, timers, network type, authentication and passive-interface behaviour. Do not choose an answer only because the devices can ping.
Detailed technical explanation
OSPF questions usually test the details that control adjacency and route selection. Read the neighbour state, area, router ID and interface configuration before deciding what is wrong.
Key takeaway
OSPF neighbour adjacency depends on matching area, hello/dead timers, network type, and authentication — IP reachability alone is not enough.
Real-world example
A network engineer at a university connects two campus buildings via a fibre link. Both routers run OSPF, but no adjacency forms — even though both routers can ping each other. The engineer finds one router is in area 0 and the other in area 1. OSPF adjacency requires matching area numbers, hello/dead timers, and network type. IP reachability alone is not enough.
What to study next
Review OSPF neighbour requirements — matching area type, hello and dead timers, network type, stub flags, and authentication. Study show ip ospf neighbor states (INIT, 2-WAY, FULL). Then practise related NSE7 OSPF questions on adjacency and route selection.
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FAQ
Advanced Networking and SD-WAN — This question tests Advanced Networking and SD-WAN — OSPF neighbours must agree on key parameters..
The correct answer is: BFD can be configured under the interface or routing protocol to detect forwarding path failures — BFD (Bidirectional Forwarding Detection) is configured under the interface or routing protocol to provide fast failure detection. It is not enabled by default. Option A is incorrect because BFD must be configured. Option B is incorrect because BFD uses dedicated sessions, not sharing OSPF hello intervals. Option D is incorrect because BFD does not use performance SLA; SLAs are separate health checks.
Review OSPF neighbour requirements — matching area type, hello and dead timers, network type, stub flags, and authentication. Study show ip ospf neighbor states (INIT, 2-WAY, FULL). Then practise related NSE7 OSPF questions on adjacency and route selection.
OSPF neighbours must agree on key parameters.
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Same concept, more angles
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. An administrator wants to use BFD with OSPF to detect link failures faster. What must be configured on the FortiGate?
mediumVariation 2. An administrator wants to use BFD to detect failures in an OSPF neighbor relationship faster than OSPF hello timers. They configure 'config router ospf' and 'set bfd enable'. However, BFD sessions are not coming up. What is a possible reason?
mediumWhy A: BFD requires that the interface has BFD enabled at the interface level and that the OSPF neighbor also supports BFD.
Variation 3. A FortiGate is using BFD for BGP fast failure detection. The administrator wants to ensure that if the BFD session goes down, the BGP neighbor is removed and routes are withdrawn immediately. Which configuration is necessary?
mediumLast reviewed: Jun 21, 2026
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.
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