The correct answer focuses on how OSPF route selection metric vs AD operate at different layers of the routing decision. Within OSPF, the cost metric—derived from interface bandwidth—determines the best path to a destination, and OSPF supports equal-cost multi-path (ECMP) to load-balance across multiple routes with identical cost. However, when comparing OSPF routes against routes from other protocols like EIGRP or static routes, administrative distance (AD) takes precedence, with OSPF’s default AD of 110 being used to decide which route is installed in the routing table. On the CCNA 200-301 v2 exam, this distinction is frequently tested by presenting scenarios where cost and AD are confused, or where process IDs are incorrectly treated as globally significant. A common trap is assuming OSPF’s metric can be compared across different routing protocols—it cannot, because each protocol uses its own metric scale. Memory tip: cost picks the path inside OSPF, AD picks the protocol outside OSPF.
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 cost as its metric to calculate the best path within the OSPF routing domain based on interface bandwidth.. 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.
Which two statements accurately describe OSPF route selection or behavior at the CCNA level?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
OSPF uses cost as its metric for choosing paths within OSPF.
OSPF uses cost as its metric for path selection within the protocol, and OSPF routes are compared against other route sources using administrative distance when cross-protocol decisions are needed. OSPF supports equal-cost multi-path (ECMP), meaning it can install multiple equal-cost paths to the same destination, so option E is incorrect. The wrong answers confuse cost with administrative distance, treat process IDs as globally significant, or incorrectly direct cross-protocol metric comparisons.
Key principle: OSPF uses cost as its metric to calculate the best path within the OSPF routing domain based on interface bandwidth.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✓
OSPF uses cost as its metric for choosing paths within OSPF.
Why this is correct
This is correct because cost is the standard OSPFmetric.
Related concept
OSPF uses cost as its metric to calculate the best path within the OSPF routing domain based on interface bandwidth.
✗
OSPF compares its metric directly against EIGRP metrics across protocols.
Why it's wrong here
This is wrong because metrics from different protocols are not compared directly in that way.
When this WOULD be correct
If the exam question asked about inter-protocol route selection or the behavior of routing protocols in a mixed environment, where OSPF and EIGRP metrics were being compared for route selection, then this option could be correct.
✓
OSPF route preference versus other route sources involves administrative distance.
Why this is correct
This is correct because administrative distance is used when comparing route sources across protocols.
Related concept
OSPF uses cost as its metric to calculate the best path within the OSPF routing domain based on interface bandwidth.
✗
OSPF process IDs must match between all neighboring routers.
Why it's wrong here
This is wrong because OSPF process IDs are locally significant.
When this WOULD be correct
In a different context, a question could ask about OSPF configuration requirements for establishing neighbor relationships. If it specified that process IDs must match for a specific feature or scenario, then this option could be correct.
✗
OSPF can never install equal-cost paths.
Why it's wrong here
This is wrong because OSPF can support equal-cost multipath behavior.
When this WOULD be correct
In a question specifically asking about OSPF's limitations in a scenario where only a single path is allowed due to configuration constraints or specific network designs, this option could be correct. For example, if the question states that OSPF is configured to not allow ECMP due to a specific policy.
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.
✓OSPF uses cost as its metric for choosing paths within OSPF.Correct answer▾
Why this is correct
This is correct because cost is the standard OSPF metric.
✗OSPF compares its metric directly against EIGRP metrics across protocols.Wrong answer — click to see why▾
Why this is wrong here
OSPF and EIGRP use different metrics (cost vs. composite metric) that are not directly comparable. Route selection between protocols is determined by administrative distance, not by comparing metrics directly.
★ When this WOULD be the correct answer
If the exam question asked about inter-protocol route selection or the behavior of routing protocols in a mixed environment, where OSPF and EIGRP metrics were being compared for route selection, then this option could be correct.
Why candidates choose this
Students might think that since both are routing protocols, their metrics can be compared directly, but they are calculated differently and are not interchangeable.
✗OSPF process IDs must match between all neighboring routers.Wrong answer — click to see why▾
Why this is wrong here
OSPF process IDs are locally significant and only matter on the local router. Two neighboring routers can have different process IDs and still form an adjacency as long as other OSPF parameters (area ID, network type, etc.) match.
★ When this WOULD be the correct answer
In a different context, a question could ask about OSPF configuration requirements for establishing neighbor relationships. If it specified that process IDs must match for a specific feature or scenario, then this option could be correct.
Why candidates choose this
Students often confuse OSPF process IDs with EIGRP autonomous system numbers, which must match between neighbors. This leads to the incorrect assumption that OSPF process IDs must also match.
✗OSPF can never install equal-cost paths.Wrong answer — click to see why▾
Why this is wrong here
OSPF supports equal-cost multipath (ECMP) by default, allowing up to 4 (or more with configuration) equal-cost paths to be installed in the routing table. This provides load balancing across multiple links.
★ When this WOULD be the correct answer
In a question specifically asking about OSPF's limitations in a scenario where only a single path is allowed due to configuration constraints or specific network designs, this option could be correct. For example, if the question states that OSPF is configured to not allow ECMP due to a specific policy.
Why candidates choose this
Some students may think OSPF only uses a single best path because they are familiar with the SPF algorithm's loop-free property, but ECMP is a standard feature in OSPF.
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 frequent exam trap is confusing OSPF’s cost metric with administrative distance or thinking that OSPF process IDs must match between neighbors. Many candidates incorrectly believe that OSPF compares its metric directly against EIGRP metrics or that process IDs are globally significant. This misunderstanding leads to wrong answers because OSPF cost is only used internally within OSPF to select the best path, while administrative distance is used to compare routes from different protocols. Also, OSPF process IDs are locally significant identifiers and do not need to match for adjacency to form.
Detailed technical explanation
How to think about this question
Open Shortest Path First (OSPF) is a link-state routing protocol that uses cost as its metric to determine the best path to a destination within an OSPF domain. The cost metric is calculated based on the bandwidth of the outgoing interface, with higher bandwidth interfaces having lower cost values. This allows OSPF to select the most efficient route by summing the costs of all links along a path and choosing the route with the lowest total cost.
When OSPF routes are compared to routes learned from other routing protocols, the router uses administrative distance (AD) to decide which route to install in the routing table. Administrative distance is a value that rates the trustworthiness of a routing source, with lower values being preferred. OSPF has a default AD of 110, which means if a route from another protocol has a lower AD, it will be preferred over OSPF. This mechanism ensures consistent and predictable routing decisions across multiple protocols.
A common exam trap involves confusing OSPF’s cost metric with administrative distance or assuming OSPF process IDs must match between neighbors. In reality, OSPF cost is used only within OSPF for path selection, while administrative distance compares routes across protocols. Additionally, OSPF process IDs are locally significant and do not need to match on neighboring routers. Understanding these distinctions helps avoid mistakes and clarifies how OSPF behaves in practical Cisco network environments.
KKey Concepts to Remember
OSPF uses cost as its metric to calculate the best path within the OSPF routing domain based on interface bandwidth.
Administrative distance is used to compare and select routes from different routing protocols, including OSPF versus EIGRP.
OSPF process IDs are locally significant and do not need to match between neighboring routers to establish adjacency.
OSPF supports equal-cost multipath (ECMP) routing by installing multiple routes with the same cost in the routing table.
OSPF does not compare its cost metric directly against metrics from other routing protocols like EIGRP.
A lower administrative distance value causes a route to be preferred when multiple protocols provide routes to the same destination.
OSPF cost is calculated by summing the cost of all outgoing interfaces along a path, favoring higher bandwidth links.
OSPF routes are installed in the routing table only if they have the lowest administrative distance compared to other sources.
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 cost as its metric to calculate the best path within the OSPF routing domain based on interface bandwidth.
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 cost as its metric to calculate the best path within the OSPF routing domain based on interface bandwidth., then practise related 200-301 questions on the same topic to reinforce the concept.
IP Routing — This question tests IP Routing — OSPF uses cost as its metric to calculate the best path within the OSPF routing domain based on interface bandwidth..
What is the correct answer to this question?
The correct answer is: OSPF uses cost as its metric for choosing paths within OSPF. — OSPF uses cost as its metric for path selection within the protocol, and OSPF routes are compared against other route sources using administrative distance when cross-protocol decisions are needed. OSPF supports equal-cost multi-path (ECMP), meaning it can install multiple equal-cost paths to the same destination, so option E is incorrect. The wrong answers confuse cost with administrative distance, treat process IDs as globally significant, or incorrectly direct cross-protocol metric comparisons.
What should I do if I get this 200-301 question wrong?
Review oSPF uses cost as its metric to calculate the best path within the OSPF routing domain based on interface bandwidth., then practise related 200-301 questions on the same topic to reinforce the concept.
What is the key concept behind this question?
OSPF uses cost as its metric to calculate the best path within the OSPF routing domain based on interface bandwidth.
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