NSE7 Advanced Networking and SD-WAN Practice Question
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?
⚠ Common exam trap
Many exam-takers assume enabling BFD under the OSPF process alone is sufficient, overlooking the separate interface-level BFD configuration required on FortiGate, unlike some other vendors where a single command enables BFD across all OSPF interfaces.
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 interface has 'set bfd enable' missing under config system interface
On FortiGate, enabling BFD under the OSPF process alone does not activate BFD on the interface. The interface itself must also have 'set bfd enable' under 'config system interface' to allow BFD session establishment. Option C is incorrect because while BFD generally requires both ends to enable it, the question specifically asks for a reason on the local FortiGate's configuration; the neighbor's configuration is outside the administrator's control for this scenario, and the most common oversight is the interface-level setting.
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 interface has 'set bfd enable' missing under config system interface
Why this is correct
Correct. The interface-level BFD enablement is required for BFD sessions to form over OSPF, and it is a common omission.
- ✗
OSPF is configured with 'network point-to-multipoint'
Why it's wrong here
Incorrect. The network type point-to-multipoint does not prevent BFD from working; BFD supports various OSPF network types.
- ✗
The neighbor does not have BFD enabled on its OSPF configuration
Why it's wrong here
Incorrect. Although BFD requires both ends to enable it, the question asks for a possible reason on the local FortiGate. The neighbor may have BFD enabled, but the local interface missing the setting is the more direct cause.
- ✗
The FortiGate's BFD transmit interval is set too high
Why it's wrong here
Incorrect. Setting the BFD transmit interval too high may affect detection speed but should not prevent BFD sessions from coming up entirely.
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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.