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 for forwarding packets.. 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 a default route and a specific route to 203.0.113.0/24. Which route is used for traffic to 203.0.113.25?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The specific route to 203.0.113.0/24
The specific route to 203.0.113.0/24 is used because it is a more specific match than the default route. In plain language, even though the default route could technically match almost anything, the router always prefers a route that more precisely describes the destination network. Since 203.0.113.25 is inside 203.0.113.0/24, that route wins under longest-prefix match.
This is one of the most basic routing-table interpretation rules. The default route remains important as a fallback, but it is not chosen when a more specific valid route exists.
Key principle: A router uses the longest-prefix match rule to select the most specific route for forwarding packets.
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 specific route to 203.0.113.0/24
Why this is correct
This is correct because it is more specific than the default route.
Related concept
A router uses the longest-prefix match rule to select the most specific route for forwarding packets.
✗
The default route
Why it's wrong here
This is wrong because the default route is used only when no more specific route matches.
When this WOULD be correct
If the question stated that the router only had a default route and no specific routes, then the default route would be used for all traffic, including to 203.0.113.25. This would make option B the correct answer.
✗
Both routes are always load-balanced
Why it's wrong here
This is wrong because that is not the default behavior simply because both routes exist.
When this WOULD be correct
In a question where multiple routes to the same destination exist and the router is configured to use equal-cost multi-path (ECMP) routing, the answer could be correct if the question specifies that both routes are valid and can be utilized simultaneously for load balancing.
✗
Neither route because defaults cannot coexist with specific routes
Why it's wrong here
This is wrong because defaults commonly coexist with more specific routes.
When this WOULD be correct
In a scenario where a question states that the router is configured to only accept one route type at a time, and it explicitly mentions that specific routes override default routes, this option would be 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 specific route to 203.0.113.0/24Correct answer▾
Why this is correct
This is correct because it is more specific than the default route.
✗The default routeWrong answer — click to see why▾
Why this is wrong here
The default route is used for traffic to destinations not explicitly defined in the routing table. Since there is a specific route to 203.0.113.0/24, that route will take precedence for traffic to 203.0.113.25.
★ When this WOULD be the correct answer
If the question stated that the router only had a default route and no specific routes, then the default route would be used for all traffic, including to 203.0.113.25. This would make option B the correct answer.
Why candidates choose this
Candidates may mistakenly believe that the default route is a catch-all for all traffic, leading them to choose it without fully considering the presence of a specific route that takes precedence.
✗Both routes are always load-balancedWrong answer — click to see why▾
Why this is wrong here
This option is incorrect because routing protocols do not load-balance traffic between a specific route and a default route; the more specific route will always take precedence for matching traffic.
★ When this WOULD be the correct answer
In a question where multiple routes to the same destination exist and the router is configured to use equal-cost multi-path (ECMP) routing, the answer could be correct if the question specifies that both routes are valid and can be utilized simultaneously for load balancing.
Why candidates choose this
Candidates may choose this option due to a misunderstanding of routing principles, believing that multiple routes can be used simultaneously for the same destination without recognizing the precedence of specific routes over default routes.
✗Neither route because defaults cannot coexist with specific routesWrong answer — click to see why▾
Why this is wrong here
This option is wrong because default routes can coexist with specific routes; the router will prioritize the specific route to 203.0.113.0/24 for traffic to 203.0.113.25.
★ When this WOULD be the correct answer
In a scenario where a question states that the router is configured to only accept one route type at a time, and it explicitly mentions that specific routes override default routes, this option would be correct.
Why candidates choose this
Candidates may choose this option due to a misunderstanding of routing principles, believing that specific routes cannot coexist with default routes, leading to confusion about how routing tables function.
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
Remember that the router always prefers the most specific route, not the default route, when a specific match is available.
Detailed technical explanation
How to think about this question
Routing in IP networks relies on the principle of longest-prefix match, where a router selects the most specific route available for forwarding packets. A specific route, such as 203.0.113.0/24, defines a precise subnet and matches destination IP addresses within that range. In contrast, a default route (0.0.0.0/0) acts as a catch-all path used only when no more specific route exists. This behavior ensures efficient and accurate packet delivery by prioritizing detailed routing information over generic fallbacks.
When a router receives a packet destined for 203.0.113.25, it compares the destination IP against its routing table entries. Since 203.0.113.25 falls within the 203.0.113.0/24 subnet, the router uses the specific route to forward the packet. The default route is ignored in this case because the specific route has a longer prefix length, making it a better match. This decision process is fundamental in Cisco routing and is consistently applied across routing protocols and static routes.
A common exam trap is assuming that the default route might be used even when a specific route exists, especially if the default route is configured with a lower administrative distance or metric. However, Cisco routers always apply longest-prefix match first before considering administrative distance or metric. Practically, this means that default routes coexist with specific routes as fallback options, but they never override more precise routes. Understanding this hierarchy prevents misconfiguration and routing errors in real networks.
KKey Concepts to Remember
A router uses the longest-prefix match rule to select the most specific route for forwarding packets.
A specific route like 203.0.113.0/24 matches destination IP addresses within that subnet more precisely than a default route.
The default route 0.0.0.0/0 is used only when no more specific route exists in the routing table.
Cisco routers always prefer routes with longer subnet masks before considering administrative distance or metric values.
Default routes commonly coexist with specific routes and serve as fallback paths in routing tables.
Routing decisions are based first on prefix length, then on administrative distance and metric if multiple routes have the same prefix length.
A packet destined for 203.0.113.25 matches the 203.0.113.0/24 route because it falls within that subnet range.
Misunderstanding the precedence of longest-prefix match over default routes is a frequent cause of routing misconfigurations.
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 for forwarding packets.
Real-world example
How this comes up in practice
A small business has 20 workstations on the 192.168.1.0/24 network and one public IP from its ISP. The router uses PAT (NAT overload) so all 20 devices share one public address using different source ports. NAT questions test whether you understand the four address terms and which direction each translation applies.
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 for forwarding packets., 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 for forwarding packets..
What is the correct answer to this question?
The correct answer is: The specific route to 203.0.113.0/24 — The specific route to 203.0.113.0/24 is used because it is a more specific match than the default route. In plain language, even though the default route could technically match almost anything, the router always prefers a route that more precisely describes the destination network. Since 203.0.113.25 is inside 203.0.113.0/24, that route wins under longest-prefix match.
This is one of the most basic routing-table interpretation rules. The default route remains important as a fallback, but it is not chosen when a more specific valid route exists.
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 for forwarding packets., 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 for forwarding packets.
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