Question 1mediummultiple choice
Full question →mediummultiple choiceObjective-mapped
A router learns 203.0.113.0/24 through OSPF and 203.0.113.0/25 through a static route. Which route is used for traffic destined to 203.0.113.10?
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
The OSPF /24 route
Longest-prefix match takes priority over the less specific /24.
B
Best answer
The static /25 route
Correct. The /25 is more specific and matches the destination.
C
Distractor review
Both routes equally
Equal-cost behavior is not based on mixed prefix lengths like this.
D
Distractor review
Neither route because the prefixes overlap
Overlapping routes are normal; the most specific match wins.
Common exam trap
Common exam trap: answer the scenario, not the keyword
A frequent exam trap is to incorrectly believe that the OSPF route with a /24 mask will be used simply because OSPF is a dynamic routing protocol and often preferred over static routes. Candidates may overlook the fundamental routing principle of longest-prefix match, which prioritizes the route with the most specific subnet mask regardless of the routing protocol. Another mistake is to confuse administrative distance with prefix specificity; administrative distance only comes into play when multiple routes have the same prefix length. This misunderstanding leads to selecting the less specific /24 route instead of the correct /25 static route.
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 scenario, the router has two routes to the 203.0.113.0 network: an OSPF-learned route with a /24 mask and a static route with a /25 mask. Since 203.0.113.10 falls within both subnets, the router evaluates which prefix is more specific to forward the traffic. The router compares the subnet masks and prefers the route with the longest prefix length, which is the /25 static route in this case. Even though OSPF is a dynamic routing protocol and static routes usually have a lower administrative distance, the prefix length takes priority when matching the destination IP. The router first finds all matching routes and then selects the one with the most specific subnet mask before considering administrative distance or metric. A common exam trap is to assume that the dynamic OSPF route will always be preferred over a static route or that administrative distance alone determines route selection. However, Cisco routers first perform longest-prefix matching to find the best route. Overlapping routes are normal in routing tables, and the router always forwards packets based on the most specific route that matches the destination IP address, which in this case is the static /25 route.
KKey Concepts to Remember
- Routers use longest-prefix match to select the most specific route that matches the destination IP address before considering administrative distance or metrics.
- A route with a longer subnet mask (more bits) is preferred over a less specific route even if the less specific route is learned via a dynamic routing protocol like OSPF.
- Static routes can override dynamic routes if the static route has a longer prefix length matching the destination IP address.
- Administrative distance is only compared when multiple routes have the same prefix length and match the destination IP address.
- Overlapping routes in a routing table are common and routers forward packets based on the most specific matching route.
- OSPF advertises routes with their subnet masks, but the router still applies longest-prefix matching to determine the best route.
- The router first filters routes by prefix match, then selects the route with the longest prefix, and finally uses administrative distance to break ties.
- Understanding prefix specificity prevents common mistakes where candidates incorrectly assume dynamic routes always override static routes.
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?
Routers use longest-prefix match to select the most specific route that matches the destination IP address before considering administrative distance or metrics.
What is the correct answer to this question?
The correct answer is: The static /25 route — Routers prefer the most specific matching route first. The /25 route is more specific than the /24 and includes 203.0.113.10.
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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