Question 1hardmultiple choice
Full question →hardmultiple choiceObjective-mapped
Exhibit
R1# show ip route O 10.30.5.0/24 [110/20] via 192.0.2.2 S 10.30.5.128/25 [1/0] via 192.0.2.6 S* 0.0.0.0/0 [1/0] via 198.51.100.1 Destination being tested: 10.30.5.130
Based on the exhibit, which route will the router use for destination 10.30.5.130?
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
Best answer
The static route to 10.30.5.128/25
This is correct because 10.30.5.130 falls inside the more specific /25 route.
B
Distractor review
The OSPF route to 10.30.5.0/24
This is wrong because the /24 is less specific than the /25.
C
Distractor review
The default route
This is wrong because more specific matching routes exist.
D
Distractor review
No route, because the destination is outside all prefixes shown.
This is wrong because the destination clearly matches both the /24 and the /25.
Common exam trap
Common exam trap: answer the scenario, not the keyword
A frequent exam trap is to select the OSPF route or default route instead of the static route because candidates mistakenly believe dynamic routes or default routes override static routes. The trap lies in confusing administrative distance with prefix length. Administrative distance only matters when two routes have the same prefix length. Here, the static route has a longer prefix (/25) than the OSPF route (/24), so the router chooses the static route regardless of administrative distance. Misunderstanding longest prefix match leads to incorrect answers and confusion about route selection priority.
Technical deep dive
How to think about this question
Routing decisions in Cisco routers 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 question, the destination IP 10.30.5.130 falls within both the 10.30.5.0/24 and 10.30.5.128/25 subnets. Since /25 has a longer prefix (more bits fixed) than /24, the router prefers the /25 route. This behavior ensures traffic is forwarded along the most precise path available, optimizing network efficiency and reducing ambiguity. The router first matches the destination IP against all known routes in its routing table. It then compares the subnet masks of matching routes and selects the one with the longest subnet mask (highest prefix length). Static routes, OSPF routes, and default routes can all be present simultaneously, but the longest prefix match rule overrides administrative distance or metric considerations when determining which route to use for a specific destination IP. Thus, even if the OSPF route or default route exists, the static /25 route is chosen because it is more specific. A common exam trap is to assume that dynamic routing protocols like OSPF always take precedence over static routes or that default routes are used when multiple matches exist. However, the router always uses the longest prefix match first, regardless of route source. This means a static route with a longer prefix will be preferred over a dynamic route with a shorter prefix. Practically, this ensures precise routing and avoids routing loops or suboptimal paths, which is critical in complex enterprise networks.
KKey Concepts to Remember
- The router selects the route with the longest matching prefix to forward packets to the destination IP address.
- Longest prefix match means a route with a more specific subnet mask (higher prefix length) is preferred over less specific routes.
- Static routes can override dynamic routes if the static route has a longer prefix match for the destination IP.
- Administrative distance is only considered when multiple routes have the same prefix length in the routing table.
- Default routes are used only when no more specific matching routes exist for the destination IP address.
- OSPF advertises routes with specific prefixes, but the router still prefers longer prefix static routes over OSPF routes with shorter prefixes.
- The router compares all matching routes and chooses the one with the highest subnet mask bits to ensure precise routing.
- Misunderstanding longest prefix match leads to common exam mistakes, especially confusing route source priority with prefix specificity.
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.
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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?
The router selects the route with the longest matching prefix to forward packets to the destination IP address.
What is the correct answer to this question?
The correct answer is: The static route to 10.30.5.128/25 — The router uses the route with the longest matching prefix. In practical terms, 10.30.5.130 matches both the /24 and the /25 shown, but the /25 is more specific. That means the router chooses the /25 route even though other routes, including a default route, are also present in the table. This is a classic longest-prefix match question and one of the most important route-selection skills on the exam.
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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