Question 1hardmultiple choice
Full question →hardmultiple choiceObjective-mapped
A router has routes to 192.168.0.0/16 and 192.168.50.0/24. Which route is used for traffic to 192.168.50.99?
Answer choices
Why each option matters
Good practice is not just finding the correct option. The wrong answers often show the exact trap the exam wants you to fall into.
A
Distractor review
192.168.0.0/16
This is wrong because the /16 is less specific than the matching /24.
B
Best answer
192.168.50.0/24
This is correct because it is the more specific route for the destination.
C
Distractor review
The default route
This is wrong because a specific matching route exists.
D
Distractor review
Both routes equally
This is wrong because the more specific route is preferred.
Common exam trap
Common exam trap: answer the scenario, not the keyword
A frequent exam trap is selecting the less specific route (192.168.0.0/16) for the destination 192.168.50.99 because it seems to cover a larger address range. Candidates might mistakenly believe that a broader route takes precedence or that both routes are equally valid. This misunderstanding ignores the fundamental Cisco routing rule of longest prefix match, which always prefers the route with the most specific subnet mask. Misreading this can lead to incorrect answers and confusion about how routing tables operate in real networks.
Technical deep dive
How to think about this question
Routing decisions in Cisco devices rely on the principle of longest prefix match, where the router selects the route with the most specific subnet mask that matches the destination IP address. This means that among multiple routes that cover the destination IP, the one with the smallest subnet (largest mask length) is preferred. This behavior ensures traffic is forwarded along the most precise path available in the routing table. In this scenario, the router has two routes: 192.168.0.0/16 and 192.168.50.0/24. Both routes include the destination IP 192.168.50.99, but the /24 route is more specific because it covers a smaller range of IP addresses. Cisco routers use the longest prefix match rule to choose 192.168.50.0/24 over 192.168.0.0/16, ensuring traffic is routed optimally. A common exam trap is assuming that the broader route (192.168.0.0/16) would be used simply because it appears first or is more general. However, Cisco routing always prefers the most specific route. Practically, this means that even if a less specific route exists, it will be ignored for matching destinations if a more specific route is present. Understanding this behavior is critical for subnetting and routing questions on the CCNA exam.
KKey Concepts to Remember
- Cisco routers use the longest prefix match rule to select the most specific route for a given destination IP address.
- A route with a smaller subnet mask (larger prefix length) is preferred over a broader route when both match the destination.
- Routing tables can contain overlapping routes, but the router always forwards packets based on the most specific matching entry.
- Default routes are only used when no specific or more specific routes exist for the destination IP address.
- The presence of multiple matching routes does not cause load balancing unless equal-cost multipath routing is configured.
- Subnetting determines the specificity of routes, directly impacting which route a router selects for forwarding traffic.
- Understanding longest prefix match is essential for interpreting routing behavior and troubleshooting IP connectivity issues.
- Cisco routing decisions prioritize prefix length over administrative distance or metric when choosing between routes in the same routing table.
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.
Related practice questions
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Use these pages to review the topic behind this question. This is how one missed question becomes focused revision.
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More questions from this exam
Keep practising from the same exam bank, or move into a focused topic page if this question exposed a weak area.
Question 1
A router learns the same prefix from both OSPF and EIGRP. Which route is installed by default?
Question 2
A router shows this output: R1#show ip ospf neighbor Neighbor ID Pri State Dead Time Address Interface 10.1.1.2 1 FULL/DR 00:00:34 192.168.12.2 GigabitEthernet0/0 10.1.1.3 1 2WAY/DROTHER 00:00:39 192.168.12.3 GigabitEthernet0/0 Which statement is correct?
Question 3
What is the OSPF metric called?
Question 4
A non-root switch has two uplinks toward the root bridge. One path has a lower total STP cost than the other. What role will the lower-cost uplink have?
Question 5
A router interface applies this ACL inbound: 10 deny tcp any any eq 80 20 permit ip any any A user reports that web browsing to a server by IP address fails, but ping works. Which statement best explains the behavior?
Question 6
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?
FAQ
Questions learners often ask
What does this 200-301 question test?
Cisco routers use the longest prefix match rule to select the most specific route for a given destination IP address.
What is the correct answer to this question?
The correct answer is: 192.168.50.0/24 — The 192.168.50.0/24 route is used because it is more specific. In practical terms, even though the /16 also matches, the router always prefers the route that describes the destination more narrowly. Since 192.168.50.99 falls inside the /24, longest-prefix match chooses that entry. This is a basic but essential routing rule. The broader /16 still matters for other destinations in 192.168.0.0/16, but not for this one.
What should I do if I get this 200-301 question wrong?
Then try more questions from the same exam bank and focus on understanding why the wrong options are tempting.
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