hardMultiple SelectObjective-mapped
300-410 Practice Question: Which TWO actions will prevent a CoPP policy from…
Which TWO actions will prevent a CoPP policy from inadvertently dropping legitimate routing protocol packets during a traffic spike? (Choose TWO.)
⚠ Common exam trap
Cisco often tests the misconception that any policing action (like exceed-action drop) is acceptable for routing protocol traffic, but the trap is that candidates forget that routing protocol packets must never be dropped, so only actions that guarantee transmission (like violate-action transmit or marking without drop) are correct.
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.
Using 'conform-action transmit' and 'violate-action transmit' ensures that routing protocol packets are never dropped, even if they exceed the configured police rate. This prevents CoPP from inadvertently dropping critical control plane traffic during a traffic spike, as the violate-action overrides the default drop behavior. The other correct option, D, uses a high CIR and burst size with 'exceed-action set-dscp cs6' to mark but not drop routing protocol packets, preserving them while still applying QoS treatment.
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.
- ✗
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'.
Why this is correct
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.
- ✗
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.
Quick reference
Routing Protocol Comparison
| Protocol | Metric | Max Hops | Algorithm | Type |
|---|---|---|---|---|
| RIP v2 | Hop count | 15 | Bellman-Ford | Distance vector |
| OSPF | Cost (bandwidth) | Unlimited | Dijkstra (SPF) | Link state |
| EIGRP | Composite metric | Unlimited | DUAL | Hybrid |
| IS-IS | Cost | Unlimited | Dijkstra | Link state |
| BGP | Policy / attributes | Unlimited | Path vector | Path vector |
RIP's 15-hop limit makes it unsuitable for large networks. OSPF and EIGRP dominate modern enterprise deployments.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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.