Question 1,046 of 2,152
Route RedistributionmediumMultiple ChoiceObjective-mapped

Quick Answer

The answer is that the OSPF route is being installed in the routing table despite EIGRP’s lower default administrative distance, indicating the EIGRP route was likely withdrawn or not learned. This occurs because the `debug ip routing` output shows the Routing Information Base (RIB) process comparing routes; when EIGRP’s route is missing or invalid, the router falls back to the next best source, OSPF with AD 110, even though EIGRP’s AD of 90 is normally preferred. On the Cisco CCNP ENARSI 300-410 exam, this scenario tests your understanding of route selection and redistribution behavior—a common trap is assuming the lower AD always wins, but the debug reveals the EIGRP route simply isn’t present for comparison. The key takeaway is that `debug ip routing` logs every route addition and comparison, so you must read the sequence: if a “better route” message appears for a higher-AD protocol, it means the lower-AD candidate was never successfully added. Memory tip: “If EIGRP is missing, OSPF gets the kissing.”

300-410 Route Redistribution Practice Question

This 300-410 practice question tests your understanding of route redistribution. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. 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.

A network engineer runs the following command to troubleshoot a Route Redistribution issue:

R1# debug ip routing

And sees the following output:

*Mar  1 00:12:34.567: RT: add 192.168.10.0/24 via 10.1.1.2, ospf metric [110/20]
*Mar  1 00:12:34.568: RT: add 192.168.10.0/24 via 10.2.2.2, eigrp metric [90/156160]
*Mar  1 00:12:34.569: RT: better route for 192.168.10.0/24 via 10.1.1.2, ospf metric [110/20]
*Mar  1 00:12:34.570: RT: add 192.168.10.0/24 to rib via 10.1.1.2, ospf metric [110/20]

What does this output indicate?

Question 1mediummultiple choice
Review the full OSPF breakdown →

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

OSPF route is being installed in the routing table because the EIGRP route may have been withdrawn or not learned.

The debug ip routing output shows the routing table process comparing routes from different sources. OSPF has administrative distance 110 and EIGRP has 90, so EIGRP is preferred by default. However, the output shows OSPF being chosen, indicating that the EIGRP route might have been removed or the OSPF route is being redistributed with a lower distance or the EIGRP route is not installed due to other reasons.

Key principle: OSPF neighbour adjacency depends on matching area, hello/dead timers, network type, and authentication — IP reachability alone is not enough.

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 route is preferred over EIGRP because OSPF has a lower metric.

    Why it's wrong here

    Metric is only compared within the same routing protocol; administrative distance is used between protocols. EIGRP has AD 90, OSPF has AD 110, so EIGRP would normally be preferred.

  • EIGRP route is preferred because it has a lower administrative distance.

    Why it's wrong here

    The output shows OSPF route being added to RIB, not EIGRP. EIGRP has lower AD but the OSPF route is chosen, possibly because EIGRP route was removed or not present.

  • OSPF route is being installed in the routing table because the EIGRP route may have been withdrawn or not learned.

    Why this is correct

    The debug shows OSPF route being added to RIB. The EIGRP route is considered but not installed, likely because it was withdrawn or not valid. The router compares and selects the OSPF route.

    Related concept

    OSPF neighbours must agree on key parameters.

  • Both routes are installed in the routing table for load balancing.

    Why it's wrong here

    Only one route is added to RIB. The debug shows only OSPF route being added; the EIGRP route is not installed.

Common exam traps

Common exam trap: OSPF can fail even when IP connectivity looks correct

OSPF neighbour formation depends on matching areas, timers, network type, authentication and passive-interface behaviour. Do not choose an answer only because the devices can ping.

Trap categories for this question

  • Command / output trap

    The output shows OSPF route being added to RIB, not EIGRP. EIGRP has lower AD but the OSPF route is chosen, possibly because EIGRP route was removed or not present.

Detailed technical explanation

How to think about this question

OSPF questions usually test the details that control adjacency and route selection. Read the neighbour state, area, router ID and interface configuration before deciding what is wrong.

KKey Concepts to Remember

  • OSPF neighbours must agree on key parameters.
  • Router ID selection can affect neighbour relationships and LSDB output.
  • OSPF cost influences the preferred path.
  • A route can appear in OSPF information but not become the installed route.

TExam Day Tips

  • Check area mismatch first when OSPF adjacency fails.
  • Review passive interfaces when a network is advertised but no neighbour forms.
  • Use show ip ospf neighbor and show ip route clues carefully.

Key takeaway

OSPF neighbour adjacency depends on matching area, hello/dead timers, network type, and authentication — IP reachability alone is not enough.

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.

What to study next

Got this wrong? Here's your next step.

Review OSPF neighbour requirements — matching area type, hello and dead timers, network type, stub flags, and authentication. Study show ip ospf neighbor states (INIT, 2-WAY, FULL). Then practise related 300-410 OSPF questions on adjacency and route selection.

Related practice questions

Related 300-410 practice-question pages

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FAQ

Questions learners often ask

What does this 300-410 question test?

Route Redistribution — This question tests Route Redistribution — OSPF neighbours must agree on key parameters..

What is the correct answer to this question?

The correct answer is: OSPF route is being installed in the routing table because the EIGRP route may have been withdrawn or not learned. — The debug ip routing output shows the routing table process comparing routes from different sources. OSPF has administrative distance 110 and EIGRP has 90, so EIGRP is preferred by default. However, the output shows OSPF being chosen, indicating that the EIGRP route might have been removed or the OSPF route is being redistributed with a lower distance or the EIGRP route is not installed due to other reasons.

What should I do if I get this 300-410 question wrong?

Review OSPF neighbour requirements — matching area type, hello and dead timers, network type, stub flags, and authentication. Study show ip ospf neighbor states (INIT, 2-WAY, FULL). Then practise related 300-410 OSPF questions on adjacency and route selection.

What is the key concept behind this question?

OSPF neighbours must agree on key parameters.

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Last reviewed: Jun 18, 2026

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