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 that matches the destination IP address in its routing table.. 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 routing table contains these entries for the same destination space: 10.1.0.0/16, 10.1.10.0/24, and 0.0.0.0/0. Which route is used for traffic to 10.1.10.44?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
10.1.10.0/24
The 10.1.10.0/24 route is used because it is the most specific matching prefix. In plain language, even though the /16 route and the default route could also match, the /24 route describes the destination range more precisely. Longest-prefix match therefore selects the /24 entry.
This is a foundational route-selection rule. The default route remains important as a fallback, but it is not used when more specific routes exist. Likewise, the /16 route is less specific than the /24, so it loses for this destination.
Key principle: A router uses the longest-prefix match rule to select the most specific route that matches the destination IP address in its routing table.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
10.1.0.0/16
Why it's wrong here
This is wrong because the /16 is less specific than the matching /24 route.
When this WOULD be correct
In a different scenario where the routing table only includes the entry 10.1.0.0/16 and no more specific routes for 10.1.10.0/24, the 10.1.0.0/16 route would be the correct answer for traffic to 10.1.10.44, as it would be the only available route.
✓
10.1.10.0/24
Why this is correct
This is correct because 10.1.10.44 falls within that more specific prefix.
Related concept
A router uses the longest-prefix match rule to select the most specific route that matches the destination IP address in its routing table.
✗
0.0.0.0/0
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
In a different scenario where the routing table only contains the default route 0.0.0.0/0 and no other specific routes, any traffic, including to 10.1.10.44, would be directed through this default route. A question could specify that no other routes exist.
✗
No route, because the entries overlap
Why it's wrong here
This is wrong because overlapping routes are normal and longest-prefix match resolves the decision.
When this WOULD be correct
In a different scenario where the routing table entries are configured incorrectly or the router is set to reject overlapping routes, a question could ask what happens when two routes overlap, leading to confusion about which route is used. In such a case, if the question specified that overlapping routes are not allowed, this option could 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.
✓10.1.10.0/24Correct answer▾
Why this is correct
This is correct because 10.1.10.44 falls within that more specific prefix.
✗10.1.0.0/16Wrong answer — click to see why▾
Why this is wrong here
The route 10.1.0.0/16 is less specific than the /24 route for the destination 10.1.10.44. The router uses the longest prefix match, so the /24 route is preferred over the /16 route.
★ When this WOULD be the correct answer
In a different scenario where the routing table only includes the entry 10.1.0.0/16 and no more specific routes for 10.1.10.0/24, the 10.1.0.0/16 route would be the correct answer for traffic to 10.1.10.44, as it would be the only available route.
Why candidates choose this
Students might think that since 10.1.10.44 falls within the 10.1.0.0/16 range, the /16 route would be used, but they overlook the more specific /24 route.
✗0.0.0.0/0Wrong answer — click to see why▾
Why this is wrong here
The default route 0.0.0.0/0 is only used when no more specific route matches the destination. Since 10.1.10.44 matches the /24 route, the default route is not considered.
★ When this WOULD be the correct answer
In a different scenario where the routing table only contains the default route 0.0.0.0/0 and no other specific routes, any traffic, including to 10.1.10.44, would be directed through this default route. A question could specify that no other routes exist.
Why candidates choose this
Students may confuse the default route as a catch-all that overrides other routes, but it is actually the least preferred route and only used as a last resort.
✗No route, because the entries overlapWrong answer — click to see why▾
Why this is wrong here
Overlapping routes are normal in routing tables and do not cause a 'no route' situation. The router resolves the conflict by selecting the route with the longest prefix match.
★ When this WOULD be the correct answer
In a different scenario where the routing table entries are configured incorrectly or the router is set to reject overlapping routes, a question could ask what happens when two routes overlap, leading to confusion about which route is used. In such a case, if the question specified that overlapping routes are not allowed, this option could be correct.
Why candidates choose this
Students might think that overlapping routes create ambiguity or errors, but routers are designed to handle overlapping prefixes using the longest prefix match algorithm.
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 exam trap is selecting the less specific route (10.1.0.0/16) or the default route (0.0.0.0/0) for the destination 10.1.10.44. Candidates might mistakenly believe that overlapping routes cause conflicts or that the default route overrides specific routes. However, Cisco routers always apply the longest-prefix match rule, choosing the most specific subnet mask that fits the destination IP. Overlapping routes do not cause routing failures; instead, they provide multiple options where the router picks the best match. Misunderstanding this can lead to incorrect answers and confusion about routing behavior.
Detailed technical explanation
How to think about this question
Routing tables store multiple routes to various destination networks, each identified by a network prefix and subnet mask. When a router receives a packet, it uses the destination IP address to find the best matching route in its routing table. The core principle governing this selection is the longest-prefix match rule, which means the router chooses the route with the most specific subnet mask that matches the destination IP address.
In this question, the routing table contains three entries: 10.1.0.0/16, 10.1.10.0/24, and 0.0.0.0/0. The destination IP 10.1.10.44 falls within both the /16 and /24 subnets, but the /24 prefix is more specific because it has a longer subnet mask (24 bits vs. 16 bits). Therefore, the router selects the 10.1.10.0/24 route for forwarding the packet. The default route 0.0.0.0/0 is only used if no other more specific route matches the destination.
A common exam trap involves misunderstanding overlapping routes and default routes. Overlapping routes are normal in routing tables, and the router always prefers the longest-prefix match. The default route serves as a catch-all for unknown destinations and is not preferred over any specific route. In practical networking, this behavior ensures efficient routing by directing traffic to the most precise path available, reducing unnecessary hops and improving network performance.
KKey Concepts to Remember
A router uses the longest-prefix match rule to select the most specific route that matches the destination IP address in its routing table.
Routes with longer subnet masks (higher prefix lengths) are preferred over less specific routes when forwarding traffic.
The default route 0.0.0.0/0 is only used when no other more specific route matches the destination IP address.
Overlapping routes in a routing table are normal and do not cause routing conflicts; the router resolves them by prefix specificity.
Cisco routers compare destination IP addresses against all routes and install the route with the highest prefix length in the forwarding table.
A less specific route like 10.1.0.0/16 covers a broader range of addresses but is overridden by any more specific route like 10.1.10.0/24.
Routing decisions are based on prefix length first, then administrative distance and metric if multiple routes have the same prefix length.
Understanding subnetting and prefix lengths is essential for correctly interpreting routing table entries and route selection.
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 that matches the destination IP address in its routing table.
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 that matches the destination IP address in its routing table., 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 that matches the destination IP address in its routing table..
What is the correct answer to this question?
The correct answer is: 10.1.10.0/24 — The 10.1.10.0/24 route is used because it is the most specific matching prefix. In plain language, even though the /16 route and the default route could also match, the /24 route describes the destination range more precisely. Longest-prefix match therefore selects the /24 entry.
This is a foundational route-selection rule. The default route remains important as a fallback, but it is not used when more specific routes exist. Likewise, the /16 route is less specific than the /24, so it loses for this destination.
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 that matches the destination IP address in its routing table., 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 that matches the destination IP address in its routing table.
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