This 200-301 practice question tests your understanding of ip routing. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. A key principle to apply: a router uses the longest prefix match rule to select the most specific route to a destination IP address.. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
A router has an OSPF-learned route to a destination prefix and also a directly connected route to a broader supernet that includes that destination. The OSPF route is more specific. Which route is used for the destination?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The more specific OSPF route
The more specific OSPF route is used. In practical terms, route specificity is checked before broader route-source considerations when the prefixes are different. Even though the connected route is a directly attached source and often strongly trusted, it still loses if it is less specific than another matching route.
This is a subtle route-selection question because it combines source type and specificity. The key is that longest-prefix match comes first.
Key principle: A router uses the longest prefix match rule to select the most specific route to a destination IP address.
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 more specific OSPF route
Why this is correct
This is correct because the most specific matching prefix is preferred first.
Related concept
A router uses the longest prefix match rule to select the most specific route to a destination IP address.
✗
The directly connected broader route
Why it's wrong here
This is wrong because a less specific connected route does not beat a more specific match.
When this WOULD be correct
In a scenario where the OSPF route is down or not available, and the question asks which route would be used for the destination, the directly connected broader route would then be the correct answer as it would be the only available route.
✗
Both routes equally
Why it's wrong here
This is wrong because the more specific route is selected.
When this WOULD be correct
In a different question where both routes are equally preferred due to equal administrative distances or when using a routing policy that allows for load balancing, the exam could state that both routes are valid and can be used simultaneously for the destination prefix.
✗
Neither route can be used because the sources differ
Why it's wrong here
This is wrong because routers can compare different sources and still choose the best matching route.
When this WOULD be correct
In a different scenario, if the question stated that both routes were from different routing protocols and the router was configured to not use OSPF routes due to administrative distance settings, then this option could be correct, indicating that neither route would be used.
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 more specific OSPF routeCorrect answer▾
Why this is correct
This is correct because the most specific matching prefix is preferred first.
✗The directly connected broader routeWrong answer — click to see why▾
Why this is wrong here
The directly connected broader route is less specific (shorter prefix length) than the OSPF route. According to the longest prefix match rule, the more specific route is always preferred, regardless of administrative distance or routing protocol source.
★ When this WOULD be the correct answer
In a scenario where the OSPF route is down or not available, and the question asks which route would be used for the destination, the directly connected broader route would then be the correct answer as it would be the only available route.
Why candidates choose this
Students might think that directly connected routes have a lower administrative distance (0) than OSPF (110), so they would be preferred. However, prefix length takes precedence over administrative distance in the route selection process.
✗Both routes equallyWrong answer — click to see why▾
Why this is wrong here
A router cannot use two routes for the same destination simultaneously; it selects a single best route based on the longest prefix match. Equal-cost multipath (ECMP) only applies when multiple routes have the same prefix length and metric, which is not the case here.
★ When this WOULD be the correct answer
In a different question where both routes are equally preferred due to equal administrative distances or when using a routing policy that allows for load balancing, the exam could state that both routes are valid and can be used simultaneously for the destination prefix.
Why candidates choose this
Students may confuse this scenario with ECMP, where multiple routes to the same destination are used for load balancing. However, ECMP requires identical prefix lengths and metrics, not different prefix lengths.
✗Neither route can be used because the sources differWrong answer — click to see why▾
Why this is wrong here
Routers can compare routes from different sources (e.g., connected, static, OSPF) and select the best one based on prefix length, administrative distance, and metric. The source difference does not prevent route selection; the longest prefix match is applied first.
★ When this WOULD be the correct answer
In a different scenario, if the question stated that both routes were from different routing protocols and the router was configured to not use OSPF routes due to administrative distance settings, then this option could be correct, indicating that neither route would be used.
Why candidates choose this
Students might think that routes from different sources are incomparable or that administrative distance alone determines the winner. However, prefix length is the primary factor, and different sources are compared normally.
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?”
Common exam traps
Common exam trap: answer the scenario, not the keyword
A common exam trap is assuming that directly connected routes always take precedence over OSPF routes because they have a lower administrative distance. Candidates may incorrectly select the broader directly connected route, forgetting that routers first apply longest prefix match before considering administrative distance. This leads to the mistaken belief that a less specific connected route overrides a more specific OSPF route. The trap is confusing route source preference with prefix specificity, which can cause incorrect answers on routing questions involving multiple route sources.
Detailed technical explanation
How to think about this question
In IP routing, routers use the longest prefix match rule to determine the best route to forward packets. This means that when multiple routes to a destination exist, the router selects the route with the most specific subnet mask, or longest prefix, that matches the destination IP address. OSPF (Open Shortest Path First) is a dynamic routing protocol that advertises routes learned from other routers, while directly connected routes are those learned from interfaces physically attached to the router.
When a router has both an OSPF-learned route and a directly connected route that covers the destination, the router first compares the prefix lengths. The more specific route (longer prefix) is preferred regardless of the administrative distance or source type. Even though directly connected routes have an administrative distance of 0 and are generally preferred, they lose out if a more specific route exists from another source such as OSPF. This ensures precise routing and efficient packet delivery.
A common exam trap is assuming that directly connected routes always override dynamic routes due to their lower administrative distance. However, the router applies longest prefix match before considering administrative distance. Practically, this means a broader directly connected route will not be used if a more specific OSPF route exists. Understanding this subtlety is critical for CCNA candidates to avoid misinterpreting route selection behavior in Cisco routers.
KKey Concepts to Remember
A router uses the longest prefix match rule to select the most specific route to a destination IP address.
OSPF advertises routes learned dynamically and these routes can be more specific than directly connected routes.
Directly connected routes have an administrative distance of 0 but do not override more specific routes from other sources.
When multiple routes exist, the router compares prefix lengths before considering administrative distance or route source.
The most specific matching prefix is always preferred regardless of whether it is learned via OSPF or directly connected.
Routers do not use multiple routes simultaneously if one route is a more specific match to the destination.
Route selection prioritizes prefix specificity first, then administrative distance, then metric if prefixes are equal.
Understanding longest prefix match prevents common mistakes in interpreting route selection between connected and OSPF routes.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
A router uses the longest prefix match rule to select the most specific route to a destination IP address.
Real-world example
How this comes up in practice
A network engineer at a university connects two campus buildings via a fibre link. Both routers run OSPF, but no adjacency forms — even though both routers can ping each other. The engineer finds one router is in area 0 and the other in area 1. OSPF adjacency requires matching area numbers, hello/dead timers, and network type. IP reachability alone is not enough.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this 200-301 question in full detail.
Review a router uses the longest prefix match rule to select the most specific route to a destination IP address., then practise related 200-301 questions on the same topic to reinforce the concept.
IP Routing — This question tests IP Routing — A router uses the longest prefix match rule to select the most specific route to a destination IP address..
What is the correct answer to this question?
The correct answer is: The more specific OSPF route — The more specific OSPF route is used. In practical terms, route specificity is checked before broader route-source considerations when the prefixes are different. Even though the connected route is a directly attached source and often strongly trusted, it still loses if it is less specific than another matching route.
This is a subtle route-selection question because it combines source type and specificity. The key is that longest-prefix match comes first.
What should I do if I get this 200-301 question wrong?
Review a router uses the longest prefix match rule to select the most specific route to a destination IP address., then practise related 200-301 questions on the same topic to reinforce the concept.
What is the key concept behind this question?
A router uses the longest prefix match rule to select the most specific route to a destination IP address.
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