The answer is a misconfigured class-map that fails to match EIGRP’s multicast address 224.0.0.10, causing EIGRP packets to fall into class-default and be policed at the much lower rate of 100 pps. Control Plane Policing (CoPP) applies policy-map actions to traffic destined for the router’s control plane, and EIGRP uses the multicast group 224.0.0.10 for neighbor hello packets. If the class-map designed to match EIGRP does not explicitly include this multicast address—or uses an incorrect match criterion—those packets are not recognized and are instead handled by class-default, which in this scenario is policed at only 100 pps. Even though the actual EIGRP packet rate is well below the intended 1000 pps, the misclassification starves the hellos, leading to neighbor flapping. On the Cisco CCNP ENARSI 300-410 exam, this tests your understanding of CoPP classification logic and the importance of matching Layer 3 multicast addresses in ACLs. A common trap is assuming that matching the protocol name alone is sufficient; remember that EIGRP’s control-plane traffic is multicast, not unicast. Memory tip: “EIGRP flaps when CoPP misses the 224.0.0.10 gap.”
300-410 EIGRP Troubleshooting Practice Question
This 300-410 practice question tests your understanding of eigrp troubleshooting. 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.
An engineer configures Control Plane Policing (CoPP) on a router with a policy-map that matches EIGRP packets and sets a police rate of 1000 pps. The class-default is configured with a police rate of 100 pps. Unexpectedly, EIGRP neighbor relationships start flapping, even though the EIGRP packet rate is well below 1000 pps. 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.
The class-map matching EIGRP does not include multicast address 224.0.0.10, causing EIGRP packets to fall into class-default and be policed at 100 pps.
EIGRP uses multicast; if the ACL doesn't match it, CoPP treats it as default traffic.
B
The police rate of 1000 pps is too low for EIGRP hello packets, causing drops.
Why wrong: 1000 pps is typically sufficient for EIGRP hellos.
C
CoPP must be applied to the management interface, not the control plane.
Why wrong: CoPP is applied to the control plane using `service-policy input` under control-plane.
D
The class-default police rate must be higher than the EIGRP class rate.
Why wrong: Class-default should be lower, but the issue is misclassification.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The class-map matching EIGRP does not include multicast address 224.0.0.10, causing EIGRP packets to fall into class-default and be policed at 100 pps.
CoPP applies to packets destined to the control plane. EIGRP uses multicast address 224.0.0.10. If the class matching EIGRP does not include the multicast group or uses an incorrect match criterion, EIGRP packets may fall into class-default and be policed at the lower rate (100 pps). This is a common misconfiguration where the ACL or class-map does not properly match EIGRP traffic.
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 class-map matching EIGRP does not include multicast address 224.0.0.10, causing EIGRP packets to fall into class-default and be policed at 100 pps.
Why this is correct
EIGRP uses multicast; if the ACL doesn't match it, CoPP treats it as default traffic.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
The police rate of 1000 pps is too low for EIGRP hello packets, causing drops.
Why it's wrong here
1000 pps is typically sufficient for EIGRP hellos.
✗
CoPP must be applied to the management interface, not the control plane.
Why it's wrong here
CoPP is applied to the control plane using `service-policy input` under control-plane.
✗
The class-default police rate must be higher than the EIGRP class rate.
Why it's wrong here
Class-default should be lower, but the issue is misclassification.
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.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this 300-410 question in full detail.
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.
EIGRP Troubleshooting — This question tests EIGRP Troubleshooting — OSPF neighbours must agree on key parameters..
What is the correct answer to this question?
The correct answer is: The class-map matching EIGRP does not include multicast address 224.0.0.10, causing EIGRP packets to fall into class-default and be policed at 100 pps. — CoPP applies to packets destined to the control plane. EIGRP uses multicast address 224.0.0.10. If the class matching EIGRP does not include the multicast group or uses an incorrect match criterion, EIGRP packets may fall into class-default and be policed at the lower rate (100 pps). This is a common misconfiguration where the ACL or class-map does not properly match EIGRP traffic.
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.
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 →
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. A network uses Control Plane Policing (CoPP) to protect the router. Router R1 has CoPP policy applied that rate-limits all traffic to 1 Mbps. R1 shows: 'show policy-map control-plane' indicates drops for EIGRP packets. R1's EIGRP neighbor R2 is flapping. What is the root cause?
hard
✓ A.The CoPP policy rate-limits EIGRP packets to 1 Mbps, but EIGRP hellos are small and frequent; the rate-limit may still drop them if the policer is not properly configured for burst.
B.R2 is sending too many EIGRP packets, exceeding the rate-limit.
C.R1 has an ACL that blocks EIGRP packets before they reach the control plane.
D.The CoPP policy is applied to the wrong interface.
Why A: CoPP rate-limits control plane traffic, including EIGRP hellos. If the rate is too low, hellos are dropped, causing the neighbor relationship to flap.
Last reviewed: Jun 18, 2026
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.
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.
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.
Sign in to join the discussion.