- A
Create a class-map that matches routing protocol packets (e.g., OSPF, EIGRP, BGP) and assign a police rate with conform-action transmit and exceed-action drop.
Why wrong: Incorrect. Using exceed-action drop will drop legitimate routing packets during spikes, which can cause routing instability.
- B
Create a class-map that matches routing protocol packets and assign a police rate with conform-action transmit and violate-action transmit.
Correct. Using transmit for both conform and violate actions ensures routing protocol packets are never dropped, even during spikes.
- C
Place routing protocol traffic into a class with a 'drop' action to prevent it from overwhelming the control plane.
Why wrong: Incorrect. Dropping routing protocol traffic would cause loss of routing adjacencies and network instability.
- D
Use the 'police' command with a high committed information rate (CIR) and burst size, and apply 'conform-action transmit' and 'exceed-action set-dscp cs6'.
Correct. Setting a high CIR and using set-dscp (instead of drop) for exceeding traffic ensures that routing packets are re-marked but not dropped, preserving protocol stability.
- E
Apply the CoPP policy only to the 'control-plane host' subinterface, which processes all routing protocol packets.
Why wrong: Incorrect. The 'control-plane host' subinterface handles packets destined to the router itself, including routing protocols, but applying CoPP only there does not prevent drops; the policy actions still apply.
Quick Answer
The answer is to use the 'police' command with a high committed information rate (CIR) and burst size, applying 'conform-action transmit' and 'exceed-action set-dscp cs6' rather than a drop action. This is correct because CoPP must protect routing protocols from being dropped during a traffic spike by ensuring that legitimate protocol packets are never subjected to a 'drop' action in any exceed or violate threshold; instead, marking them with DSCP CS6 preserves their priority without discarding them. On the Cisco CCNP ENARSI 300-410 exam, this question tests your understanding that CoPP policies should classify routing protocol traffic into a high-priority class with a guaranteed transmit action, and a common trap is choosing 'exceed-action drop' which would inadvertently discard critical routing updates. A useful memory tip is "never drop a route—mark it high instead," reinforcing that routing protocol packets should always be transmitted, even if they exceed the police rate.
300-410 Control Plane Policing (CoPP) Practice Question
This 300-410 practice question tests your understanding of control plane policing (copp). Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. 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.
Which TWO actions will prevent a CoPP policy from inadvertently dropping legitimate routing protocol packets during a traffic spike? (Choose TWO.)
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
Create a class-map that matches routing protocol packets and assign a police rate with conform-action transmit and violate-action transmit.
To protect routing protocols, CoPP should classify routing protocol traffic into a high-priority class with a conform-action of 'transmit' and a violate-action of 'transmit' (or a high bandwidth guarantee). Using a 'police' with 'conform-action transmit' and 'exceed-action drop' is too aggressive. The 'drop' action in any class that matches routing protocols is dangerous. 'set-dscp' does not prevent drops.
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.
- ✗
Create a class-map that matches routing protocol packets (e.g., OSPF, EIGRP, BGP) and assign a police rate with conform-action transmit and exceed-action drop.
Why it's wrong here
Incorrect. Using exceed-action drop will drop legitimate routing packets during spikes, which can cause routing instability.
- ✓
Create a class-map that matches routing protocol packets and assign a police rate with conform-action transmit and violate-action transmit.
Why this is correct
Correct. Using transmit for both conform and violate actions ensures routing protocol packets are never dropped, even during spikes.
Related concept
OSPF neighbours must agree on key parameters.
- ✗
Place routing protocol traffic into a class with a 'drop' action to prevent it from overwhelming the control plane.
Why it's wrong here
Incorrect. Dropping routing protocol traffic would cause loss of routing adjacencies and network instability.
- ✓
Use the 'police' command with a high committed information rate (CIR) and burst size, and apply 'conform-action transmit' and 'exceed-action set-dscp cs6'.
- ✗
Apply the CoPP policy only to the 'control-plane host' subinterface, which processes all routing protocol packets.
Why it's wrong here
Incorrect. The 'control-plane host' subinterface handles packets destined to the router itself, including routing protocols, but applying CoPP only there does not prevent drops; the policy actions still apply.
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.
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FAQ
Questions learners often ask
What does this 300-410 question test?
Control Plane Policing (CoPP) — This question tests Control Plane Policing (CoPP) — OSPF neighbours must agree on key parameters..
What is the correct answer to this question?
The correct answer is: Create a class-map that matches routing protocol packets and assign a police rate with conform-action transmit and violate-action transmit. — To protect routing protocols, CoPP should classify routing protocol traffic into a high-priority class with a conform-action of 'transmit' and a violate-action of 'transmit' (or a high bandwidth guarantee). Using a 'police' with 'conform-action transmit' and 'exceed-action drop' is too aggressive. The 'drop' action in any class that matches routing protocols is dangerous. 'set-dscp' does not prevent drops.
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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