350-601 Security Practice Question
A network engineer is troubleshooting CoPP drops on a Cisco Nexus 9000 switch. The 'show control-plane' output indicates that packets are being dropped due to 'CoPP' on the 'default' control-plane class. Which action is most likely to resolve the issue without affecting routing protocol stability?
⚠ Common exam trap
Cisco often tests the misconception that all CoPP drops indicate a need to reclassify traffic to a higher priority class, when in fact the 'default' class drop is a classic sign of an undersized catch-all policer that simply needs a rate adjustment.
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 policer rate for the 'default' class in the CoPP policy.
The 'default' class in a CoPP policy catches all control-plane traffic not explicitly matched by higher-priority classes. Drops in this class indicate that the aggregate policer rate for unmatched traffic is too low. Increasing the policer rate for the 'default' class allows more legitimate control-plane packets (e.g., ARP, BFD, or management traffic) to pass without impacting the dedicated policers for critical protocols like OSPF or BGP, thus preserving routing stability.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Disable CoPP globally to allow all control-plane traffic.
Why it's wrong here
Disabling CoPP removes protection against DoS attacks.
- ✓
Increase the policer rate for the 'default' class in the CoPP policy.
Why this is correct
Raising the policer rate allows more packets to pass, reducing drops.
- ✗
Modify the class-map to reclassify the dropped packets to a higher priority class.
Why it's wrong here
Reclassification may starve other traffic and is not a direct fix.
- ✗
Increase the ingress buffer size on the control-plane interface.
Why it's wrong here
Buffering only delays drops, does not solve policer drops.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This 350-601 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 350-601 exam.