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 Cisco router selects the route with the longest-prefix match as the primary forwarding path for a given 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 learns 10.0.0.0/8 from OSPF and 10.10.0.0/16 from a static route. Which route is used for traffic to 10.10.20.1?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The static 10.10.0.0/16 route
The static /16 route is used because it is more specific than the OSPF /8 route. In practical terms, even though both routes match the destination, the router chooses the one that narrows the destination range more precisely. Since 10.10.20.1 belongs to 10.10.0.0/16, that entry wins.
This question reinforces that longest-prefix match comes first. The broader OSPF route still matters for other destinations inside 10.0.0.0/8, but not for this one.
Key principle: A Cisco router selects the route with the longest-prefix match as the primary forwarding path for a given 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 OSPF 10.0.0.0/8 route
Why it's wrong here
This is wrong because the /8 is less specific than the matching /16.
When this WOULD be correct
In a different scenario where the OSPF route 10.0.0.0/8 is the only available route and no more specific routes exist for 10.10.20.1, the OSPF route would be used. For example, if a question stated that the static route was removed or invalidated, then the OSPF route would be the correct answer.
✓
The static 10.10.0.0/16 route
Why this is correct
This is correct because it is the more specific matching route.
Related concept
A Cisco router selects the route with the longest-prefix match as the primary forwarding path for a given destination IP address.
✗
The default route if present
Why it's wrong here
This is wrong because more specific matching routes already exist.
When this WOULD be correct
If the question stated that the router has no specific routes for 10.10.20.1 and only a default route configured, then the default route would be used for traffic to that destination. This would occur in a scenario where the static and OSPF routes were not present.
✗
Neither route, because the networks overlap
Why it's wrong here
This is wrong because overlapping prefixes are normal and longest-prefix match resolves the decision.
When this WOULD be correct
In a different scenario, if the question stated that both routes were configured with conflicting subnet masks or if the OSPF route was incorrectly configured to include the 10.10.0.0/16 range, then this option could be correct, indicating that neither route is usable due to overlap.
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 static 10.10.0.0/16 routeCorrect answer▾
Why this is correct
This is correct because it is the more specific matching route.
✗The OSPF 10.0.0.0/8 routeWrong answer — click to see why▾
Why this is wrong here
The OSPF route 10.0.0.0/8 is less specific (longer prefix length /8) than the static route 10.10.0.0/16 for the destination 10.10.20.1. The longest prefix match rule dictates that the route with the longest matching prefix (most specific) is chosen, regardless of administrative distance or routing protocol.
★ When this WOULD be the correct answer
In a different scenario where the OSPF route 10.0.0.0/8 is the only available route and no more specific routes exist for 10.10.20.1, the OSPF route would be used. For example, if a question stated that the static route was removed or invalidated, then the OSPF route would be the correct answer.
Why candidates choose this
Students might think that OSPF, as a dynamic routing protocol, is preferred over a static route, or they might confuse administrative distance with prefix length. They may also incorrectly assume that a larger network range (like /8) automatically takes precedence.
✗The default route if presentWrong answer — click to see why▾
Why this is wrong here
A default route (0.0.0.0/0) is only used when no other more specific route matches the destination. Since there are matching routes (10.10.0.0/16 and 10.0.0.0/8) for 10.10.20.1, the default route is not considered. The longest prefix match rule selects the most specific route among those that match.
★ When this WOULD be the correct answer
If the question stated that the router has no specific routes for 10.10.20.1 and only a default route configured, then the default route would be used for traffic to that destination. This would occur in a scenario where the static and OSPF routes were not present.
Why candidates choose this
Students may think that a default route is always used as a last resort, but they might forget that it only applies when no other route matches. They might also confuse the concept of 'default' with 'most preferred' or assume it overrides other routes.
✗Neither route, because the networks overlapWrong answer — click to see why▾
Why this is wrong here
Overlapping prefixes are common in routing tables and do not prevent route selection. The router uses the longest prefix match algorithm to choose the most specific route. Both routes are valid and can coexist; the router simply picks the best match for each destination.
★ When this WOULD be the correct answer
In a different scenario, if the question stated that both routes were configured with conflicting subnet masks or if the OSPF route was incorrectly configured to include the 10.10.0.0/16 range, then this option could be correct, indicating that neither route is usable due to overlap.
Why candidates choose this
Students might think that overlapping routes cause a conflict or error, similar to overlapping IP addresses on interfaces. They may not understand that routing tables can have multiple overlapping entries and that the longest match resolves the ambiguity.
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 frequent mistake is to assume that the OSPF route will be used simply because it is dynamically learned, or because it covers a larger network range. Candidates often overlook that the router applies longest-prefix match first, which means the more specific static route with a /16 mask takes precedence over the broader /8 OSPF route. This misunderstanding leads to incorrect answers, as the router does not ignore static routes in favor of OSPF when the static route is more specific. Remember, overlapping routes are common, and the router always chooses the route with the most specific subnet mask matching the destination.
Detailed technical explanation
How to think about this question
Routing decisions in Cisco devices rely heavily on the concept of longest-prefix match, which means the router selects the route with the most specific subnet mask that matches the destination IP address. In this scenario, the router has two routes: one learned via OSPF for 10.0.0.0/8 and one static route for 10.10.0.0/16. Both routes cover the destination IP 10.10.20.1, but the /16 prefix is more specific than the /8 prefix, narrowing the address range more precisely.
When multiple routes to the same destination exist, Cisco routers first apply longest-prefix match to determine which route to use. After prefix length, the router considers administrative distance and metric to break ties if prefixes are equal. Here, the static route has an administrative distance of 1, which is lower than OSPF’s default 110, but since the static route is already more specific, it is selected regardless. This behavior ensures traffic is forwarded via the most precise and reliable path.
A common exam trap is to assume that dynamic routing protocols like OSPF always take precedence over static routes. However, the router prioritizes prefix specificity first, then administrative distance. Overlapping routes are normal in routing tables, and the router uses longest-prefix match to resolve conflicts. Practically, this means that even if a broad OSPF route exists, more specific static routes will override it for matching destinations, ensuring optimal routing granularity.
KKey Concepts to Remember
A Cisco router selects the route with the longest-prefix match as the primary forwarding path for a given destination IP address.
Static routes have an administrative distance of 1, which is lower than OSPF’s default administrative distance of 110, making static routes more preferred when prefix lengths are equal.
When multiple routes overlap, the router uses the most specific subnet mask to determine which route to install in the routing table.
OSPF advertises routes dynamically but does not override more specific static routes in the routing table.
The router performs route selection by first comparing prefix length, then administrative distance, and finally metric if needed.
Overlapping routes in routing tables are normal and resolved by longest-prefix match, ensuring precise traffic forwarding.
A broader route like 10.0.0.0/8 covers many addresses but is less specific than a 10.10.0.0/16 route for destinations within that range.
Static routes provide explicit control over routing decisions and can override dynamic routes when configured with more specific prefixes.
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 Cisco router selects the route with the longest-prefix match as the primary forwarding path for a given 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 Cisco router selects the route with the longest-prefix match as the primary forwarding path for a given 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 Cisco router selects the route with the longest-prefix match as the primary forwarding path for a given destination IP address..
What is the correct answer to this question?
The correct answer is: The static 10.10.0.0/16 route — The static /16 route is used because it is more specific than the OSPF /8 route. In practical terms, even though both routes match the destination, the router chooses the one that narrows the destination range more precisely. Since 10.10.20.1 belongs to 10.10.0.0/16, that entry wins.
This question reinforces that longest-prefix match comes first. The broader OSPF route still matters for other destinations inside 10.0.0.0/8, but not for this one.
What should I do if I get this 200-301 question wrong?
Review a Cisco router selects the route with the longest-prefix match as the primary forwarding path for a given 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 Cisco router selects the route with the longest-prefix match as the primary forwarding path for a given destination IP address.
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