CCNA IP Routing Practice Question
A route to 10.10.20.0/24 disappears when an OSPF adjacency fails. Which design would most directly provide an automatic backup without changing the primary OSPF path during normal operation?
⚠ Common exam trap
Avoid assuming that static routes are always less preferred than dynamic routes without considering administrative distance.
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
✓
A floating static route with a higher administrative distance than OSPF
The most direct design is a floating static route with a higher administrative distance than OSPF. In plain language, that means the router keeps a manually configured backup route in reserve but does not use it while the OSPF route remains healthy. If the OSPF path disappears, the backup static route becomes active automatically. This is a very common and practical way to add simple failover. The key requirement in the question is that the primary OSPF path should remain unchanged under normal conditions. A normal static route with default distance would override OSPF and break that goal. A floating static route avoids that by staying less preferred until a failure occurs. That is why it is the correct design choice here.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
A floating static route with a higher administrative distance than OSPF
Why this is correct
A floating static route is configured with an administrative distance greater than OSPF's default of 110 (commonly 120 or 150). Because the router prefers the lowest AD, this route stays out of the routing table while OSPF is healthy, but it is immediately installed when OSPF loses the route. This gives you a backup path without ever overriding OSPF's normal forwarding decision, which is exactly what a floating route is designed to do.
- ✗
A standard static route with the default administrative distance of 1
Why it's wrong here
A standard static route uses the default administrative distance of 1, which is far lower than OSPF's 110. This means the router will always select the static route over OSPF, even when the OSPF route exists and is valid. Instead of acting as a backup, this would replace OSPF as the primary path, breaking the intended routing design and potentially forwarding traffic to a less optimal destination.
When this WOULD be correct
In a different scenario where the question asks for a static route to be preferred under all circumstances, a standard static route with an administrative distance of 1 would be correct. For example, if the question specifies that OSPF is not required and a static route should always be used for traffic to a specific destination.
- ✗
Removing OSPF entirely and using only a default route
Why it's wrong here
Removing OSPF entirely would eliminate the dynamic routing protocol that learns the full topology, and a single default route would not reproduce the specific OSPF-learned routes. This would cause traffic to be sent to a default gateway for all destinations, even those that OSPF previously routed more specifically, leading to suboptimal paths or blackholes. It changes the fundamental routing architecture instead of preserving OSPF as the working primary and simply adding a backup for the one lost route.
When this WOULD be correct
In a scenario where a network is designed to only use a default route for all outbound traffic, and OSPF is deemed unnecessary due to a simple topology, the question might ask for the most efficient routing method. In that case, using a default route would be the correct answer.
- ✗
Disabling the routing table on the router until failure occurs
Why it's wrong here
Disabling the routing table is not a viable mechanism because a router cannot forward packets without its RIB. Cisco IOS does not provide a feature to shut down the routing table while keeping the router operational, and doing so would cause all traffic to be dropped, not just traffic for the disappeared route. This approach would create complete network outage rather than providing backup connectivity during an OSPF failure.
When this WOULD be correct
In a scenario where a question asks for a method to temporarily suspend routing while performing maintenance or troubleshooting without affecting the overall network performance, disabling the routing table could be deemed appropriate to ensure no traffic is routed incorrectly during that time.
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 200-301 exam frequently reuses these exact scenarios with slightly different constraints.
✓A floating static route with a higher administrative distance than OSPFCorrect answer▾
Why this is correct
A floating static route is configured with an administrative distance greater than OSPF's default of 110 (commonly 120 or 150). Because the router prefers the lowest AD, this route stays out of the routing table while OSPF is healthy, but it is immediately installed when OSPF loses the route. This gives you a backup path without ever overriding OSPF's normal forwarding decision, which is exactly what a floating route is designed to do.
✗A standard static route with the default administrative distance of 1Wrong answer — click to see why▾
Why this is wrong here
A standard static route with the default administrative distance of 1 would override the OSPF route (AD 110) because a lower AD is preferred. This would replace the primary OSPF path with the static route, not provide a backup that only activates upon failure.
★ When this WOULD be the correct answer
In a different scenario where the question asks for a static route to be preferred under all circumstances, a standard static route with an administrative distance of 1 would be correct. For example, if the question specifies that OSPF is not required and a static route should always be used for traffic to a specific destination.
Why candidates choose this
Students may think that any static route can serve as a backup, but they overlook that the default AD of 1 makes it preferred over OSPF, thus changing the primary path rather than floating behind it.
✗Removing OSPF entirely and using only a default routeWrong answer — click to see why▾
Why this is wrong here
Removing OSPF entirely eliminates the primary dynamic routing protocol, which is not a backup solution. The question requires preserving OSPF as the normal path and only providing an automatic backup when OSPF fails.
★ When this WOULD be the correct answer
In a scenario where a network is designed to only use a default route for all outbound traffic, and OSPF is deemed unnecessary due to a simple topology, the question might ask for the most efficient routing method. In that case, using a default route would be the correct answer.
Why candidates choose this
Some might think that using only a default route simplifies the design, but this does not maintain OSPF as the primary path and does not provide a backup for the specific /24 route.
✗Disabling the routing table on the router until failure occursWrong answer — click to see why▾
Why this is wrong here
Disabling the routing table is not a valid operational practice; routers require the routing table to forward packets. This option does not provide any automatic backup mechanism and would break connectivity entirely.
★ When this WOULD be the correct answer
In a scenario where a question asks for a method to temporarily suspend routing while performing maintenance or troubleshooting without affecting the overall network performance, disabling the routing table could be deemed appropriate to ensure no traffic is routed incorrectly during that time.
Why candidates choose this
The idea of 'disabling until failure' might sound like a failover concept, but it is not how routing works. Students may confuse this with route filtering or policy-based routing, but it is not a standard feature.
Analysis generated from the official 200-301blueprint 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
Interpreting HSRP and VRRP Operational Status
Key term
OSPF adjacency
An OSPF adjacency is a logical neighbor relationship formed between two OSPF routers that have completed a series of hello and database exchange processes, enabling them to share routing information and maintain a consistent view of the network topology.
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.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This 200-301 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 200-301 exam.