Question 1hardmultiple choice
Full question →hardmultiple choiceObjective-mapped
A router has an OSPF-learned route to a destination prefix and also a directly connected route to a broader supernet that includes that destination. The OSPF route is more specific. Which route is used for the destination?
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 more specific OSPF route
This is correct because the most specific matching prefix is preferred first.
B
Distractor review
The directly connected broader route
This is wrong because a less specific connected route does not beat a more specific match.
C
Distractor review
Both routes equally
This is wrong because the more specific route is selected.
D
Distractor review
Neither route can be used because the sources differ
This is wrong because routers can compare different sources and still choose the best matching route.
Common exam trap
Common exam trap: answer the scenario, not the keyword
A common exam trap is assuming that directly connected routes always take precedence over OSPF routes because they have a lower administrative distance. Candidates may incorrectly select the broader directly connected route, forgetting that routers first apply longest prefix match before considering administrative distance. This leads to the mistaken belief that a less specific connected route overrides a more specific OSPF route. The trap is confusing route source preference with prefix specificity, which can cause incorrect answers on routing questions involving multiple route sources.
Technical deep dive
How to think about this question
In IP routing, routers use the longest prefix match rule to determine the best route to forward packets. This means that when multiple routes to a destination exist, the router selects the route with the most specific subnet mask, or longest prefix, that matches the destination IP address. OSPF (Open Shortest Path First) is a dynamic routing protocol that advertises routes learned from other routers, while directly connected routes are those learned from interfaces physically attached to the router. When a router has both an OSPF-learned route and a directly connected route that covers the destination, the router first compares the prefix lengths. The more specific route (longer prefix) is preferred regardless of the administrative distance or source type. Even though directly connected routes have an administrative distance of 0 and are generally preferred, they lose out if a more specific route exists from another source such as OSPF. This ensures precise routing and efficient packet delivery. A common exam trap is assuming that directly connected routes always override dynamic routes due to their lower administrative distance. However, the router applies longest prefix match before considering administrative distance. Practically, this means a broader directly connected route will not be used if a more specific OSPF route exists. Understanding this subtlety is critical for CCNA candidates to avoid misinterpreting route selection behavior in Cisco routers.
KKey Concepts to Remember
- A router uses the longest prefix match rule to select the most specific route to a destination IP address.
- OSPF advertises routes learned dynamically and these routes can be more specific than directly connected routes.
- Directly connected routes have an administrative distance of 0 but do not override more specific routes from other sources.
- When multiple routes exist, the router compares prefix lengths before considering administrative distance or route source.
- The most specific matching prefix is always preferred regardless of whether it is learned via OSPF or directly connected.
- Routers do not use multiple routes simultaneously if one route is a more specific match to the destination.
- Route selection prioritizes prefix specificity first, then administrative distance, then metric if prefixes are equal.
- Understanding longest prefix match prevents common mistakes in interpreting route selection between connected and OSPF 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.
Related practice questions
Related 200-301 practice-question pages
Use these pages to review the topic behind this question. This is how one missed question becomes focused revision.
CCNA subnetting practice questions
Practise IPv4 subnetting, CIDR, masks, host ranges and subnet selection.
CCNA OSPF practice questions
Practise OSPF neighbours, router IDs, metrics, areas and routing-table interpretation.
CCNA VLAN practice questions
Practise VLANs, access ports, trunks, allowed VLANs and switching scenarios.
CCNA STP practice questions
Practise spanning tree, root bridge election, port roles and STP troubleshooting.
CCNA EtherChannel practice questions
Practise LACP, PAgP, port-channel behaviour and bundle requirements.
CCNA ACL practice questions
Practise standard and extended ACLs, permit/deny logic and traffic filtering.
CCNA NAT practice questions
Practise static NAT, dynamic NAT, PAT and inside/outside address translation.
CCNA DHCP practice questions
Practise DHCP scopes, relay, leases and troubleshooting.
CCNA show ip route practice questions
Practise routing-table output, longest-prefix match, AD and route selection.
CCNA show interfaces trunk practice questions
Practise trunk verification and VLAN forwarding across switches.
CCNA wireless security practice questions
Practise WLAN security, authentication and wireless architecture concepts.
CCNA IPv6 practice questions
Practise IPv6 addressing, routes, neighbour discovery and common IPv6 exam traps.
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?
A router uses the longest prefix match rule to select the most specific route to a destination IP address.
What is the correct answer to this question?
The correct answer is: The more specific OSPF route — The more specific OSPF route is used. In practical terms, route specificity is checked before broader route-source considerations when the prefixes are different. Even though the connected route is a directly attached source and often strongly trusted, it still loses if it is less specific than another matching route. This is a subtle route-selection question because it combines source type and specificity. The key is that longest-prefix match comes first.
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.
Discussion
Loading comments…
Sign in to join the discussion.