The answer is the route with metric 20. Within the same routing protocol, OSPF uses its internal metric—a cumulative cost based on interface bandwidth—to compare paths to the same destination with an identical prefix length, and the lower metric is always preferred. This question directly tests your ability to separate administrative distance from metric: since both routes originate from OSPF, the administrative distance is identical, so the metric becomes the sole tiebreaker. On the CCNA 200-301 v2 exam, this concept often appears in scenario-based questions where a router learns multiple OSPF routes, and the common trap is confusing metric with administrative distance or assuming a higher-cost path is more reliable. Remember the memory tip: “Same protocol, same prefix—lowest metric wins the conflict.”
CCNA IP Routing Practice Question
This 200-301 practice question tests your understanding of ip routing. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. A key principle to apply: oSPF uses a cost metric based on link bandwidth to determine the best path to a destination network.. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
An OSPF router learns a route with metric 20 and another OSPF route to the same destination with metric 30. The prefix length is the same. Which path is preferred?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The route with metric 20
The OSPF path with metric 20 is preferred because, within the same routing protocol and for the same prefix length, the metric is used to compare candidate paths. In practical terms, the router is not comparing source trust here because both routes come from OSPF. It is comparing OSPF’s own internal path-cost values, and the lower metric wins.
This question is about separating administrative distance from metric. Since both routes come from the same protocol, metric is the deciding factor.
Key principle: OSPF uses a cost metric based on link bandwidth to determine the best path to a destination network.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✓
The route with metric 20
Why this is correct
This is correct because lower metric is preferred within the same routing protocol.
Related concept
OSPF uses a cost metric based on link bandwidth to determine the best path to a destination network.
✗
The route with metric 30
Why it's wrong here
This is wrong because the higher metric is less preferred.
When this WOULD be correct
In a different scenario where OSPF is configured to prefer higher metrics due to specific policy routing or administrative decisions, a question might ask which route is preferred when the metrics are intentionally inverted, making 30 the preferred choice.
✗
Both routes are rejected because the metrics differ
Why it's wrong here
This is wrong because differing metrics are normal and help choose the better path.
When this WOULD be correct
In a scenario where a question specifies that OSPF routes are only accepted if they have the same metric, and both routes have different metrics, it could state that the router rejects all routes that do not meet this criterion, making this option correct.
✗
The default route is preferred
Why it's wrong here
This is wrong because the router already has matching routes to the destination.
When this WOULD be correct
In a different scenario where the question specifies that the OSPF router has no other routes to the destination and the default route is configured, the default route would be preferred over any other routes, including those with higher metrics.
Option-by-option analysis
Why each answer is right or wrong
Understanding why wrong answers are wrong — and when they would be correct — is what separates a 750 score from a 900. The 200-301 exam frequently reuses these exact scenarios with slightly different constraints.
✓The route with metric 20Correct answer▾
Why this is correct
This is correct because lower metric is preferred within the same routing protocol.
✗The route with metric 30Wrong answer — click to see why▾
Why this is wrong here
OSPF always prefers the route with the lowest metric. A metric of 30 is higher than 20, so it is less preferred and will not be installed in the routing table unless the lower metric route fails.
★ When this WOULD be the correct answer
In a different scenario where OSPF is configured to prefer higher metrics due to specific policy routing or administrative decisions, a question might ask which route is preferred when the metrics are intentionally inverted, making 30 the preferred choice.
Why candidates choose this
Students may mistakenly think that a higher metric indicates a more reliable or recently learned route, but OSPF uses lower metric as the primary tie-breaker for equal prefix lengths.
✗Both routes are rejected because the metrics differWrong answer — click to see why▾
Why this is wrong here
OSPF does not reject routes with differing metrics; instead, it uses the metric to select the best path. Both routes are valid, but only the one with the lowest metric is installed in the routing table.
★ When this WOULD be the correct answer
In a scenario where a question specifies that OSPF routes are only accepted if they have the same metric, and both routes have different metrics, it could state that the router rejects all routes that do not meet this criterion, making this option correct.
Why candidates choose this
Some might confuse OSPF with protocols that require equal metrics for load balancing, but OSPF only load-balances when metrics are equal; differing metrics simply result in a single best path.
✗The default route is preferredWrong answer — click to see why▾
Why this is wrong here
A default route is only used when no specific route to the destination exists. Since the router has two specific OSPF routes to the destination, it will use the best one, not the default.
★ When this WOULD be the correct answer
In a different scenario where the question specifies that the OSPF router has no other routes to the destination and the default route is configured, the default route would be preferred over any other routes, including those with higher metrics.
Why candidates choose this
Students may think that a default route is always preferred as a catch-all, but specific routes always take precedence over default routes in the routing table.
Analysis generated from the official 200-301blueprint and verified against question context. The “when correct” sections are what AI assistants cite when candidates ask “what’s the difference between these options?”
Common exam traps
Common exam trap: answer the scenario, not the keyword
A common exam trap is confusing administrative distance with metric when comparing routes from the same protocol. Candidates might incorrectly think that a higher metric route is rejected or that administrative distance plays a role in choosing between two OSPF routes. In reality, OSPF always prefers the route with the lowest metric, and both routes remain valid candidates. Misunderstanding this can lead to incorrect answers about route selection or route rejection, especially when multiple OSPF routes to the same prefix exist with different metrics.
Detailed technical explanation
How to think about this question
OSPF (Open Shortest Path First) is a link-state routing protocol that uses cost as its metric to determine the best path to a destination. The cost metric in OSPF is typically based on the bandwidth of the links along the path, with lower cost values indicating preferred routes. When multiple OSPF routes to the same destination prefix exist, the router compares their metrics to select the best path.
The decision process in OSPF routing involves comparing the metrics of candidate routes learned from the same routing protocol. Since both routes in the question are OSPF routes with the same prefix length, the router selects the route with the lower metric value, which is 20 in this case. Administrative distance does not influence the choice here because both routes come from the same protocol, so metric is the sole deciding factor.
A common exam trap is confusing administrative distance with metric or assuming that differing metrics cause routes to be rejected. In reality, OSPF always prefers the route with the lowest metric and installs it in the routing table. Understanding this distinction is critical for CCNA candidates, as it reflects practical routing behavior and prevents misinterpretation of OSPF route selection in Cisco devices.
KKey Concepts to Remember
OSPF uses a cost metric based on link bandwidth to determine the best path to a destination network.
When multiple OSPF routes to the same prefix exist, the router prefers the route with the lowest OSPF metric value.
Administrative distance is not used to compare routes learned from the same routing protocol like OSPF.
OSPF routers install the route with the lowest metric into the routing table when prefix length matches.
Differing OSPF metrics do not cause route rejection; they enable the router to select the optimal path.
OSPF metric calculation reflects cumulative link costs along the path, influencing route preference.
The router compares OSPF internal path costs rather than route source trust when choosing between OSPF routes.
Understanding OSPF metric preference helps avoid confusion with other routing protocols’ administrative distance.
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.
Key takeaway
OSPF uses a cost metric based on link bandwidth to determine the best path to a destination network.
Real-world example
How this comes up in practice
A network engineer at a university connects two campus buildings via a fibre link. Both routers run OSPF, but no adjacency forms — even though both routers can ping each other. The engineer finds one router is in area 0 and the other in area 1. OSPF adjacency requires matching area numbers, hello/dead timers, and network type. IP reachability alone is not enough.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this 200-301 question in full detail.
Review oSPF uses a cost metric based on link bandwidth to determine the best path to a destination network., then practise related 200-301 questions on the same topic to reinforce the concept.
IP Routing — This question tests IP Routing — OSPF uses a cost metric based on link bandwidth to determine the best path to a destination network..
What is the correct answer to this question?
The correct answer is: The route with metric 20 — The OSPF path with metric 20 is preferred because, within the same routing protocol and for the same prefix length, the metric is used to compare candidate paths. In practical terms, the router is not comparing source trust here because both routes come from OSPF. It is comparing OSPF’s own internal path-cost values, and the lower metric wins.
This question is about separating administrative distance from metric. Since both routes come from the same protocol, metric is the deciding factor.
What should I do if I get this 200-301 question wrong?
Review oSPF uses a cost metric based on link bandwidth to determine the best path to a destination network., then practise related 200-301 questions on the same topic to reinforce the concept.
What is the key concept behind this question?
OSPF uses a cost metric based on link bandwidth to determine the best path to a destination network.
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