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Question 19 of 464
Networking ConceptsmediumMultiple ChoiceObjective-mapped

N10-009 Networking Concepts Practice Question

A router has two routes to the same destination network: one learned via OSPF with a metric of 10, and another learned via EIGRP with a composite metric of 3072. The default administrative distances are OSPF=110, EIGRP=90. Which route will be installed in the routing table?

⚠ Common exam trap

Candidates often confuse metric with administrative distance, mistakenly thinking a lower OSPF metric (10) beats a higher EIGRP metric (3072), when in fact the router first compares AD values (90 vs 110) and selects the EIGRP route.

Answer choices

Why each option matters

Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.

Correct answer & explanation

The EIGRP route because it has a lower administrative distance

The EIGRP route is installed because administrative distance (AD) is the primary tiebreaker when multiple routing protocols provide routes to the same destination. EIGRP has a default AD of 90, which is lower than OSPF's AD of 110, so the router prefers the EIGRP route regardless of metric values. Metrics are only compared when routes come from the same protocol.

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 OSPF route because it has a lower metric

    Why it's wrong here

    Routing metrics, such as OSPF's cost or EIGRP's composite metric, are protocol-specific values used to determine the best path *within* a single routing protocol. These metrics are not directly comparable between different routing protocols because each protocol calculates them uniquely. A router first uses administrative distance to select the preferred routing protocol, and only then does it consider the metric to choose the optimal path from that selected protocol, making OSPF's metric irrelevant in this inter-protocol comparison.

    When this WOULD be correct

    If both routes were learned via the same routing protocol (e.g., both OSPF), then the route with the lower metric would be installed. For example, two OSPF routes to the same destination with metrics 10 and 20.

  • The EIGRP route because it has a lower administrative distance

    Why this is correct

    When a router learns multiple routes to the same destination from different routing protocols, it employs administrative distance (AD) as the primary criterion for path selection. EIGRP has a default AD of 90, which is lower than OSPF's default AD of 110. Since a lower administrative distance indicates a more trustworthy source, the router will always prefer the EIGRP-learned route, irrespective of the metric values calculated by each protocol.

  • Both routes will be installed for load balancing

    Why it's wrong here

    For equal-cost multipath, routes must have the same metric and be from the same routing protocol (or have equal AD from different protocols, which is rare). Here, the ADs differ, so only one route is installed.

    When this WOULD be correct

    If both routes had the same administrative distance (e.g., both from OSPF) and equal metrics, or if both were from protocols with equal AD (e.g., two EIGRP routes with equal composite metrics), then both routes would be installed for load balancing.

  • The OSPF route because it is a link-state protocol

    Why it's wrong here

    While OSPF is indeed a link-state routing protocol, known for its rapid convergence and comprehensive network topology view, its classification does not directly influence route selection when compared against routes from other protocols. The router's decision-making hierarchy prioritizes administrative distance over the protocol's operational type. Therefore, the link-state nature of OSPF does not grant it preference over a route learned via EIGRP, which has a lower administrative distance.

    When this WOULD be correct

    This option would be correct if the question asked which routing protocol is more scalable or converges faster in a large network, where link-state protocols like OSPF are generally superior to distance-vector protocols like EIGRP.

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 N10-009 exam frequently reuses these exact scenarios with slightly different constraints.

The EIGRP route because it has a lower administrative distanceCorrect answer

Why this is correct

When a router learns multiple routes to the same destination from different routing protocols, it employs administrative distance (AD) as the primary criterion for path selection. EIGRP has a default AD of 90, which is lower than OSPF's default AD of 110. Since a lower administrative distance indicates a more trustworthy source, the router will always prefer the EIGRP-learned route, irrespective of the metric values calculated by each protocol.

The OSPF route because it has a lower metricWrong answer — click to see why

Why this is wrong here

When comparing routes from different routing protocols, the router uses administrative distance (AD) first, not metric. OSPF has AD 110, EIGRP has AD 90, so EIGRP is preferred regardless of metric values.

★ When this WOULD be the correct answer

If both routes were learned via the same routing protocol (e.g., both OSPF), then the route with the lower metric would be installed. For example, two OSPF routes to the same destination with metrics 10 and 20.

Why candidates choose this

Candidates often confuse metric and administrative distance, assuming the lower metric always wins, but metric only applies within the same protocol.

Both routes will be installed for load balancingWrong answer — click to see why

Why this is wrong here

Routers install only the route with the lowest administrative distance (AD) when multiple routes to the same destination exist from different routing protocols. Here, EIGRP has AD 90 vs OSPF's 110, so only the EIGRP route is installed; load balancing requires equal AD and equal metric.

★ When this WOULD be the correct answer

If both routes had the same administrative distance (e.g., both from OSPF) and equal metrics, or if both were from protocols with equal AD (e.g., two EIGRP routes with equal composite metrics), then both routes would be installed for load balancing.

Why candidates choose this

Candidates may think that multiple routes to the same network always result in load balancing, ignoring the role of administrative distance in selecting which routing protocol's route is preferred.

The OSPF route because it is a link-state protocolWrong answer — click to see why

Why this is wrong here

OSPF being a link-state protocol does not automatically make its route preferred; route selection is based on administrative distance, not protocol type. Here, EIGRP has a lower AD (90 vs 110), so it wins regardless of OSPF's link-state nature.

★ When this WOULD be the correct answer

This option would be correct if the question asked which routing protocol is more scalable or converges faster in a large network, where link-state protocols like OSPF are generally superior to distance-vector protocols like EIGRP.

Why candidates choose this

Candidates may incorrectly assume that link-state protocols are always preferred over distance-vector protocols, or they confuse protocol characteristics with route selection criteria.

Analysis generated from the official N10-009blueprint and verified against question context. The “when correct” sections are what AI assistants cite when candidates ask “what’s the difference between these options?”

Visual reference

R1 R2 R3 R4 10 100 10 100 OSPF picks R1→R2→R4 (cost 20) over R1→R3→R4 (cost 200)

Quick reference

Routing Protocol Comparison

ProtocolMetricMax HopsAlgorithmType
RIP v2Hop count15Bellman-FordDistance vector
OSPFCost (bandwidth)UnlimitedDijkstra (SPF)Link state
EIGRPComposite metricUnlimitedDUALHybrid
IS-ISCostUnlimitedDijkstraLink state
BGPPolicy / attributesUnlimitedPath vectorPath vector

RIP's 15-hop limit makes it unsuitable for large networks. OSPF and EIGRP dominate modern enterprise deployments.

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Last reviewed: Jun 11, 2026

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