CCNA IP Routing Practice Question
A router learns route 198.51.100.0/24 from OSPF with AD 110 and also has a static route to the same prefix configured with AD 150. Which route is installed?
⚠ Common exam trap
Don't assume static routes are always preferred; check the 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
✓
The OSPF route, because 110 is lower than 150
The route with the lower administrative distance is installed. A static route configured with a higher AD becomes a floating static route and remains as a backup until the preferred route disappears.
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 static route, because static routes always win
Why it's wrong here
Static routes do not always win; their administrative distance can be manually adjusted, and the default is 1, but here the static route is configured with an AD of 150, making it a floating static route. Since OSPF advertises the same prefix with an AD of 110, the router prefers the lower AD, so the static route is not used.
When this WOULD be correct
If a question stated that the router only has a static route to the prefix and no other routes with a lower AD, then the static route would be installed. For example, if the static route had an AD of 100 and there were no other routes, the static route would be preferred.
- ✓
The OSPF route, because 110 is lower than 150
Why this is correct
OSPF has a default administrative distance of 110, while the static route in this scenario has been configured with an AD of 150, making it a floating static route. Since the router selects the route with the lowest AD for the same destination prefix, the OSPF route wins. The lower AD indicates that OSPF is more trustworthy than the static route in this configuration.
- ✗
Both routes, because administrative distances are different
Why it's wrong here
The router installs only the single best route for any given prefix, selected by the lowest administrative distance, regardless of whether the competing routes have different AD values. Different ADs do not cause both routes to be installed; instead, they create a clear winner, and the losing route is held in the routing table only as a candidate if the winning route fails. Thus, having different ADs means only one route is active.
When this WOULD be correct
In a different scenario where both routes are configured with the same prefix and the same administrative distance, a question could ask if both routes would be installed. In such a case, the router could install both routes in a load-balancing situation, making this option correct.
- ✗
Neither route, because the static route is floating
Why it's wrong here
A floating static route is designed to be inactive while a more preferred route, such as an OSPF route, exists; it is configured with a higher AD precisely so it remains in standby. It does not cause the router to ignore both routes; rather, the router installs the OSPF route because its AD of 110 is lower than the static route’s AD of 150. The floating static route simply stays dormant until the OSPF route is lost.
When this WOULD be correct
If the question stated that the static route had a higher administrative distance than the OSPF route but was configured with a command that made it a floating static route (e.g., AD 200), then the static route would not be installed unless the OSPF route failed, making this option correct.
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.
✓The OSPF route, because 110 is lower than 150Correct answer▾
Why this is correct
OSPF has a default administrative distance of 110, while the static route in this scenario has been configured with an AD of 150, making it a floating static route. Since the router selects the route with the lowest AD for the same destination prefix, the OSPF route wins. The lower AD indicates that OSPF is more trustworthy than the static route in this configuration.
✗The static route, because static routes always winWrong answer — click to see why▾
Why this is wrong here
Static routes do not always win; they have a default administrative distance of 1, but in this scenario the static route was configured with AD 150, which is higher than OSPF's AD 110. Therefore, the OSPF route is preferred.
★ When this WOULD be the correct answer
If a question stated that the router only has a static route to the prefix and no other routes with a lower AD, then the static route would be installed. For example, if the static route had an AD of 100 and there were no other routes, the static route would be preferred.
Why candidates choose this
Students often memorize that static routes are preferred over dynamic routes by default, but they may forget that administrative distance can be manually set, making the static route less preferred.
✗Both routes, because administrative distances are differentWrong answer — click to see why▾
Why this is wrong here
A router installs only the best route (lowest AD) for a given prefix into the routing table. Different AD values do not cause both routes to be installed; the route with the lower AD is chosen.
★ When this WOULD be the correct answer
In a different scenario where both routes are configured with the same prefix and the same administrative distance, a question could ask if both routes would be installed. In such a case, the router could install both routes in a load-balancing situation, making this option correct.
Why candidates choose this
Students might think that different administrative distances allow multiple routes to coexist, confusing this with equal-cost multipath (ECMP) where routes have the same AD and metric.
✗Neither route, because the static route is floatingWrong answer — click to see why▾
Why this is wrong here
A floating static route is a static route with a higher AD than the dynamic route, so it remains inactive as a backup. In this case, the static route is floating, but it is still valid and will be used if the OSPF route is lost. The question asks which route is installed, and the OSPF route is installed, not neither.
★ When this WOULD be the correct answer
If the question stated that the static route had a higher administrative distance than the OSPF route but was configured with a command that made it a floating static route (e.g., AD 200), then the static route would not be installed unless the OSPF route failed, making this option correct.
Why candidates choose this
The term 'floating' might mislead students into thinking the static route is invalid or not present, but it simply means it is not active while the preferred route exists.
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
OSPFv3 Single-Area Configuration for IPv6
Key term
OSPF
OSPF is a link-state routing protocol that uses the SPF algorithm to compute the shortest path to each destination within a single autonomous system.
Key term
Floating static route
A floating static route is a backup route in a routing table that is only used when the primary route fails, because it has a higher administrative distance (lower priority).
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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.