Question 1mediummultiple choice
Full question →mediummultiple choiceObjective-mapped
When two routes to the same destination are learned by OSPF from different paths, what criterion does OSPF use to select the best path?
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
Lowest administrative distance
Distractor.
B
Best answer
Lowest OSPF cost
Correct choice.
C
Distractor review
Highest bandwidth of the first hop only
Distractor.
D
Distractor review
Lowest next-hop IP address
Distractor.
Common exam trap
Common exam trap: answer the scenario, not the keyword
A common exam trap is selecting administrative distance as the criterion for OSPF route selection. While administrative distance determines route preference between different routing protocols, OSPF uses cost internally to choose the best path. Another trap is assuming OSPF chooses routes based on the highest bandwidth of the first hop only, ignoring the cumulative cost of the entire path. Candidates may also mistakenly think OSPF uses the lowest next-hop IP address, which is incorrect. These misunderstandings can lead to incorrect answers on OSPF routing questions.
Technical deep dive
How to think about this question
OSPF (Open Shortest Path First) is a link-state routing protocol that calculates the best path to a destination by using a cost metric. This cost is assigned to each interface and typically inversely proportional to the bandwidth of the link. The router sums the costs of all interfaces along a path to determine the total path cost. The path with the lowest total cost is preferred and installed in the routing table. This metric-based approach allows OSPF to optimize routing decisions based on actual link characteristics rather than arbitrary values. When OSPF learns multiple routes to the same destination from different paths, it compares the total cost of each path. The route with the lowest cumulative cost is selected as the best path. Administrative distance, which is a measure of trustworthiness between different routing protocols, is not used to compare routes within OSPF itself. Instead, OSPF relies solely on its cost metric to make intra-protocol route decisions. This ensures consistent and predictable routing behavior within OSPF domains. A common exam trap is confusing administrative distance with OSPF cost. Administrative distance is only relevant when comparing routes from different routing protocols, such as OSPF versus EIGRP. Within OSPF, the router ignores administrative distance and focuses on cost. Another practical consideration is that OSPF cost is cumulative across all hops, not just the first link. This means a path with a high-bandwidth first hop but lower bandwidth subsequent hops may have a higher total cost than a path with consistent medium bandwidth links. Understanding this helps network engineers design efficient OSPF topologies and avoid suboptimal routing.
KKey Concepts to Remember
- OSPF selects the best route to a destination based on the lowest cumulative cost metric calculated along the entire path.
- The OSPF cost metric is typically derived from the bandwidth of each link, with higher bandwidth links having lower cost values.
- Administrative distance is a routing protocol preference value used only when comparing routes learned from different routing protocols, not within OSPF.
- When multiple OSPF routes to the same destination exist, the router sums the cost of all outgoing interfaces along each path to determine the best route.
- OSPF does not select routes based on the next-hop IP address or only the bandwidth of the first hop; it considers the total path cost.
- OSPF cost calculation helps ensure traffic is routed over the most efficient path, improving network performance and reliability.
- Routers running OSPF maintain a link-state database and use Dijkstra’s algorithm to compute the shortest path tree based on cost.
- Understanding OSPF cost and route selection is critical for designing scalable and efficient IP connectivity in Cisco networks.
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?
OSPF selects the best route to a destination based on the lowest cumulative cost metric calculated along the entire path.
What is the correct answer to this question?
The correct answer is: Lowest OSPF cost — Within OSPF, the router compares the total path cost to the destination. Lower cost is preferred. Administrative distance is used when comparing routes from different routing sources, not between two OSPF paths.
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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