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300-410 Practice Question: Examine the partial BFD configuration on a…
Examine the partial BFD configuration on a router:
interface GigabitEthernet0/0
bfd interval 100 min_rx 100 multiplier 3 !
interface GigabitEthernet0/1
bfd interval 200 min_rx 200 multiplier 3 !
router ospf 1
bfd all-interfaces !
The router has OSPF neighbors on both interfaces. Which statement is true?
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 BFD session on GigabitEthernet0/0 will detect failures in 300 ms, and on GigabitEthernet0/1 in 600 ms.
BFD timers are configured per interface. Each BFD session independently uses the timers configured on its respective interface. The multiplier is applied per session.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Both BFD sessions will use the same timer values because OSPF is configured with 'bfd all-interfaces'.
Why it's wrong here
'bfd all-interfaces' merely enables BFD for OSPF neighbours on every interface; it does not override the per-interface interval and min_rx values. Uniform timers would apply only if the interfaces lacked individual bfd commands, which they do not here.
- ✓
The BFD session on GigabitEthernet0/0 will detect failures in 300 ms, and on GigabitEthernet0/1 in 600 ms.
Why this is correct
BFD detection time equals the multiplier times the slower of interval and min_rx. Gi0/0 gives 3 × 100 ms = 300 ms; Gi0/1 gives 3 × 200 ms = 600 ms, matching the configured per-interface timers.
- ✗
The BFD session on GigabitEthernet0/1 will not form because the interval is too high.
Why it's wrong here
A 200 ms interval with a multiplier of 3 is a valid, functional BFD configuration; nothing in IOS rejects it as too high. This option would be correct only if the peer's min_rx exceeded the configured transmit interval, causing negotiation failure.
- ✗
The router will use the minimum interval across all interfaces for consistency.
Why it's wrong here
BFD timers are negotiated per interface and per session; there is no global minimum applied across interfaces. A single router-wide timer would suit a design where uniform detection is required, but IOS configures each interface's BFD parameters independently.
Visual reference
Quick reference
Routing Protocol Comparison
| Protocol | Metric | Max Hops | Algorithm | Type |
|---|---|---|---|---|
| RIP v2 | Hop count | 15 | Bellman-Ford | Distance vector |
| OSPF | Cost (bandwidth) | Unlimited | Dijkstra (SPF) | Link state |
| EIGRP | Composite metric | Unlimited | DUAL | Hybrid |
| IS-IS | Cost | Unlimited | Dijkstra | Link state |
| BGP | Policy / attributes | Unlimited | Path vector | Path vector |
RIP's 15-hop limit makes it unsuitable for large networks. OSPF and EIGRP dominate modern enterprise deployments.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This 300-410 practice question is part of Courseiva's free Cisco 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 300-410 exam.