Question 830 of 2,152

VRF-Lite →hardMultiple ChoiceObjective-mapped

Quick Answer

The answer is a low seed metric for EIGRP, typically set to a value like 1, which makes the redistributed route more attractive than the original OSPF route and causes the loop. Even when route tagging is applied to prevent re-redistribution, if the EIGRP seed metric is set too low, the redistributed prefix will have a lower metric than the original OSPF route, leading the router to prefer the EIGRP-learned version and re-inject it back into OSPF. On the Cisco CCNP ENARSI 300-410 exam, this tests your understanding that mutual redistribution loops are not solely prevented by tags—the seed metric must be high enough to avoid creating a better path. A common trap is assuming tags alone solve all loops, but the edge case here is that a low seed metric overrides tag-based filtering by making the redistributed route administratively preferred. Memory tip: “Low seed, high greed”—a low seed metric makes EIGRP greedy for the route, breaking the loop prevention.

300-410 VRF-Lite Practice Question

This 300-410 practice question tests your understanding of vrf-lite. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. 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.

In a VRF-Lite network, redistribution is configured between OSPF and EIGRP. The engineer notices that some routes are being redistributed in a loop, causing instability. The network uses route tagging, but the loop persists. Which is the most likely explanation?

Clue words in this question

Noticing these words before you look at the options changes how you read each choice.

Clue: "most likely"
Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.

Question 1hardmultiple choice

Review the full OSPF breakdown →

A
The route tag is not being propagated correctly because OSPF uses a 32-bit tag and EIGRP uses a 32-bit tag, but the tag is lost during redistribution.
Why wrong: Both OSPF and EIGRP support 32-bit tags, and tags are preserved across redistributions if configured properly.
B
The seed metric for EIGRP is set to a low value (e.g., 1), causing the redistributed route to be preferred over the original OSPF route, leading to a loop.
If the seed metric is too low, the redistributed route may have a lower composite metric than the original, causing it to be selected and re-redistributed, creating a loop.
C
The administrative distance of OSPF (110) is lower than EIGRP (90), so the redistributed route is always preferred.
Why wrong: EIGRP has a lower AD (90) than OSPF (110), so EIGRP routes are preferred. This can cause loops, but the issue is more about metric than AD.
D
The 'redistribute connected' command is used under OSPF, which redistributes all connected interfaces, including the loopback used for router ID.
Why wrong: Redistributing connected interfaces can cause issues, but it is not the primary cause of a loop in mutual redistribution.

Full breakdown with real-world context →

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 seed metric for EIGRP is set to a low value (e.g., 1), causing the redistributed route to be preferred over the original OSPF route, leading to a loop.

Mutual redistribution can cause routing loops if routes are not properly tagged and filtered. However, even with tags, if the seed metric is not set correctly, the redistributed route may have a lower metric than the original, causing it to be preferred and re-redistributed. The edge case here is that the seed metric for EIGRP (default is infinity) must be set, but if set too low, it can cause loops. Additionally, if the same prefix exists in both protocols, the administrative distance comparison may cause the redistributed route to be preferred over the original, leading to a loop.

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.

✗
The route tag is not being propagated correctly because OSPF uses a 32-bit tag and EIGRP uses a 32-bit tag, but the tag is lost during redistribution.
Why it's wrong here
Both OSPF and EIGRP support 32-bit tags, and tags are preserved across redistributions if configured properly.
✓
The seed metric for EIGRP is set to a low value (e.g., 1), causing the redistributed route to be preferred over the original OSPF route, leading to a loop.
Why this is correct
If the seed metric is too low, the redistributed route may have a lower composite metric than the original, causing it to be selected and re-redistributed, creating a loop.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
OSPF neighbours must agree on key parameters.
✗
The administrative distance of OSPF (110) is lower than EIGRP (90), so the redistributed route is always preferred.
Why it's wrong here
EIGRP has a lower AD (90) than OSPF (110), so EIGRP routes are preferred. This can cause loops, but the issue is more about metric than AD.
✗
The 'redistribute connected' command is used under OSPF, which redistributes all connected interfaces, including the loopback used for router ID.
Why it's wrong here
Redistributing connected interfaces can cause issues, but it is not the primary cause of a loop in mutual redistribution.

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.

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 300-410 practice-question pages

Use these pages to review the topic behind this question. This is how one missed question becomes focused revision.

Layer 3 Technologies practice questions

Practise 300-410 questions linked to Layer 3 Technologies.

EIGRP Troubleshooting practice questions

Practise 300-410 questions linked to EIGRP Troubleshooting.

OSPF Troubleshooting (v2/v3) practice questions

Practise 300-410 questions linked to OSPF Troubleshooting (v2/v3).

BGP Troubleshooting practice questions

Practise 300-410 questions linked to BGP Troubleshooting.

Route Redistribution practice questions

Practise 300-410 questions linked to Route Redistribution.

Policy-Based Routing (PBR) practice questions

Practise 300-410 questions linked to Policy-Based Routing (PBR).

VRF-Lite practice questions

Practise 300-410 questions linked to VRF-Lite.

Route Maps and Route Filtering practice questions

Practise 300-410 questions linked to Route Maps and Route Filtering.

Administrative Distance practice questions

Practise 300-410 questions linked to Administrative Distance.

Route Summarization practice questions

Practise 300-410 questions linked to Route Summarization.

Bidirectional Forwarding Detection (BFD) practice questions

Practise 300-410 questions linked to Bidirectional Forwarding Detection (BFD).

VPN Technologies practice questions

Practise 300-410 questions linked to VPN Technologies.

Practice this exam

Start a free 300-410 practice session

Short sessions build daily habit. Longer sessions build exam-day stamina. Try a timed session to simulate real conditions.

10 questions 20 questions 30 questions 50 questions Timed 30

300-410 practice-test guide →Study guide →Browse all practice tests

FAQ

Questions learners often ask

What does this 300-410 question test?

VRF-Lite — This question tests VRF-Lite — OSPF neighbours must agree on key parameters..

What is the correct answer to this question?

The correct answer is: The seed metric for EIGRP is set to a low value (e.g., 1), causing the redistributed route to be preferred over the original OSPF route, leading to a loop. — Mutual redistribution can cause routing loops if routes are not properly tagged and filtered. However, even with tags, if the seed metric is not set correctly, the redistributed route may have a lower metric than the original, causing it to be preferred and re-redistributed. The edge case here is that the seed metric for EIGRP (default is infinity) must be set, but if set too low, it can cause loops. Additionally, if the same prefix exists in both protocols, the administrative distance comparison may cause the redistributed route to be preferred over the original, leading to a loop.

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

Are there clue words in this question I should notice?

Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.

What is the key concept behind this question?

OSPF neighbours must agree on key parameters.

About these practice questions

Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →

How Courseiva writes practice questions · Editorial policy

Keep practising

Question Discussion

Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.

Loading comments…

This 300-410 practice question is part of Courseiva's free Cisco certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the 300-410 exam.