N10-009 Network Implementation Practice Question
An organization uses OSPF as its interior gateway protocol in a multi-area design. After a core router failure, the network takes a long time to reconverge. Which technology can be implemented to improve convergence speed?
⚠ Common exam trap
CompTIA often tests the misconception that increasing OSPF timers or using a single area speeds up convergence, when in fact BFD is the correct technology for sub-second failure detection without altering OSPF's own protocol timers.
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
✓
Implement Bidirectional Forwarding Detection (BFD)
BFD provides sub-second failure detection by sending rapid, lightweight hello packets independently of OSPF's own hello mechanism. When a core router fails, BFD detects the link down in milliseconds and immediately signals OSPF to trigger reconvergence, drastically reducing the time OSPF would otherwise spend waiting for its own dead timer to expire.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Use static routes instead of OSPF
Why it's wrong here
Using static routes instead of a dynamic routing protocol like OSPF fundamentally prevents the network from adapting to topology changes automatically. Static routes are manually configured and remain fixed, offering no inherent mechanism for detecting link failures or automatically rerouting traffic. If a link fails along a statically defined path, traffic will be black-holed until manual intervention, which is the opposite of improving convergence and network resilience.
When this WOULD be correct
In a small, stable network with no redundancy requirements, where simplicity and predictability are prioritized over dynamic routing, static routes would be correct to minimize routing overhead and control.
- ✗
Increase OSPF hello and dead timers
Why it's wrong here
Increasing OSPF hello and dead timers directly lengthens the time it takes for OSPF to detect a neighbor or link failure. The hello timer dictates how frequently a router sends hello packets to its neighbors, while the dead timer specifies how long a router waits to receive a hello packet before declaring a neighbor down. By extending these intervals, OSPF will wait longer to identify a problem, delaying the initiation of the SPF algorithm and consequently slowing down the network's overall convergence time after an event.
When this WOULD be correct
In a scenario where the network has frequent, transient link flaps causing unnecessary OSPF recalculations, increasing hello and dead timers can reduce instability and improve overall network stability.
- ✓
Implement Bidirectional Forwarding Detection (BFD)
Why this is correct
Bidirectional Forwarding Detection (BFD) is a lightweight, protocol-independent mechanism designed to provide rapid fault detection for forwarding paths between network devices. By establishing a BFD session between OSPF neighbors and sending very frequent, small hello packets (often in milliseconds), BFD can detect link or neighbor failures significantly faster than OSPF's native hello and dead timers. When BFD detects a failure, it immediately notifies OSPF, allowing the routing protocol to quickly re-converge and re-calculate routes in sub-second times, minimizing service disruption.
- ✗
Configure all routers in a single OSPF area
Why it's wrong here
Configuring all routers within a single OSPF area, especially in a large network, creates a monolithic routing domain where every router must maintain a complete Link-State Database (LSDB) for the entire network. Any topology change, such as a link failure or a new router, triggers a re-calculation of the Shortest Path First (SPF) algorithm on every router in that area. This extensive computation consumes significant CPU resources and increases the time required for the network to converge, directly impeding the goal of faster convergence.
Option-by-option analysis
Why each answer is right or wrong
Understanding why wrong answers are wrong — and when they would be correct — is what separates a 750 score from a 900. The N10-009 exam frequently reuses these exact scenarios with slightly different constraints.
✓Implement Bidirectional Forwarding Detection (BFD)Correct answer▾
Why this is correct
Bidirectional Forwarding Detection (BFD) is a lightweight, protocol-independent mechanism designed to provide rapid fault detection for forwarding paths between network devices. By establishing a BFD session between OSPF neighbors and sending very frequent, small hello packets (often in milliseconds), BFD can detect link or neighbor failures significantly faster than OSPF's native hello and dead timers. When BFD detects a failure, it immediately notifies OSPF, allowing the routing protocol to quickly re-converge and re-calculate routes in sub-second times, minimizing service disruption.
✗Use static routes instead of OSPFWrong answer — click to see why▾
Why this is wrong here
Static routes lack dynamic adaptation; they cannot improve OSPF convergence speed after a failure because they require manual intervention to update, whereas OSPF reconverges automatically.
★ When this WOULD be the correct answer
In a small, stable network with no redundancy requirements, where simplicity and predictability are prioritized over dynamic routing, static routes would be correct to minimize routing overhead and control.
Why candidates choose this
Candidates may think static routes eliminate OSPF's convergence delays entirely, overlooking that static routes do not adapt to failures at all, making convergence irrelevant but causing outages.
✗Increase OSPF hello and dead timersWrong answer — click to see why▾
Why this is wrong here
Increasing OSPF hello and dead timers would slow down failure detection, making convergence even slower, not faster.
★ When this WOULD be the correct answer
In a scenario where the network has frequent, transient link flaps causing unnecessary OSPF recalculations, increasing hello and dead timers can reduce instability and improve overall network stability.
Why candidates choose this
Candidates may think that longer timers give more time for routes to stabilize, but they overlook that this delays failure detection and extends convergence time.
Analysis generated from the official N10-009blueprint and verified against question context. The “when correct” sections are what AI assistants cite when candidates ask “what’s the difference between these options?”
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.
Go deeper
Related to this question
Learn chapter
Physical Network Infrastructure
Key term
Router
A router is a networking device that connects different networks together and directs data traffic between them by choosing the best path for data to travel.
Key term
Dead timer
The Dead timer is the period an OSPF router waits to hear from a neighbor before declaring that neighbor as unreachable and removing it from the routing table.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This N10-009 practice question is part of Courseiva's free CompTIA 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 N10-009 exam.