350-401 Security Practice Question
A network engineer is implementing Control Plane Policing (CoPP) on a Cisco IOS router to protect the route processor from excessive CPU utilization due to malicious traffic. The engineer wants to ensure that BGP, SSH, and SNMP traffic are rate-limited appropriately. After applying the CoPP policy, the engineer notices that BGP sessions are flapping. Which action should the engineer take to resolve the issue while maintaining protection?
⚠ Common exam trap
The trap here is thinking that CoPP uses queuing or that BGP graceful restart can prevent flapping caused by policer drops, when the real issue is an insufficient rate limit.
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
✓
Increase the rate limit for the class-map that matches BGP traffic.
BGP session flapping after applying CoPP typically occurs because the policer is dropping legitimate BGP control packets. The correct fix is to increase the rate limit for the BGP traffic class so that keepalives and updates are not dropped, while still protecting the control plane from excessive traffic. Other options either do not address the rate limit or suggest inappropriate mechanisms.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Remove the CoPP policy from the control plane and apply it only to the data plane.
Why it's wrong here
CoPP is specifically designed to protect the control plane, not the data plane. Applying it to the data plane would not protect the route processor from CPU overload. Removing the policy entirely would leave the router vulnerable to denial-of-service attacks. This action does not address the BGP flapping and eliminates the intended protection.
- ✗
Configure a separate class-map for BGP and assign it to a higher priority queue in the policy-map.
Why it's wrong here
CoPP uses policing, not queuing, to rate-limit control plane traffic. Priority queuing is not a feature of CoPP policy-maps. While separating BGP into its own class can help with granularity, the issue is the rate limit, not queuing. This option is incorrect because it suggests a mechanism not applicable to CoPP.
- ✗
Enable BGP graceful restart to prevent session flapping during CoPP drops.
Why it's wrong here
BGP graceful restart helps maintain forwarding during session resets, but it does not prevent the session from flapping due to CoPP drops. The root cause is the rate limit being too low, so graceful restart would not resolve the flapping. This option is incorrect because it addresses a symptom rather than the cause.
- ✓
Increase the rate limit for the class-map that matches BGP traffic.
Why this is correct
BGP sessions flapping indicate that the CoPP policy is dropping legitimate BGP keepalives or updates due to an overly restrictive rate limit. Increasing the rate limit for the BGP class-map allows sufficient BGP control traffic to reach the route processor while still protecting against excessive traffic. This balances protection with operational stability.
Visual reference
Go deeper
Related to this question
Learn chapter
Route Redistribution and Filtering
Key term
Control Plane Policing
Control Plane Policing is a Cisco security feature that protects a router or switch by rate-limiting the traffic that the device's processor must handle, preventing it from being overwhelmed.
Key term
Control Plane Protection
Control Plane Protection (CoPP) is a security feature on Cisco routers and switches that filters traffic destined to the device's control plane to prevent attacks and ensure stability.
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JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official Cisco exam blueprint
This 350-401 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 350-401 exam.