The answer is to enable IP traffic export (NetFlow) on the switch. When the IP Input process spikes, it means the switch’s CPU is busy handling packets that must be processed in software—often due to a flood of traffic destined to the CPU itself, such as SNMP, SSH, or routing updates. NetFlow provides granular flow-level data, including source and destination IPs, ports, and protocols, allowing you to pinpoint exactly which traffic is overwhelming the CPU without adding significant overhead. On the ENCOR 350-401 exam, this scenario tests your understanding of control-plane policing and traffic analysis tools; a common trap is to choose “debug ip packet,” which would worsen CPU load. Remember the memory tip: “NetFlow for the flow, debug for the dead”—debugging will crash a high-CPU switch, while NetFlow safely exports the data you need.
CCNP Network Assurance Practice Question
This 350-401 practice question tests your understanding of network assurance. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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.
A network administrator is troubleshooting high CPU utilization on a Catalyst 9300 switch. The output of 'show processes cpu sorted' shows the 'IP Input' process consuming 45% CPU. Which tool should be used to identify the specific packets causing the issue?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Enable IP traffic export (NetFlow) on the switch.
The 'IP Input' process handles incoming IP packets that require CPU processing, such as routing protocol updates, management traffic, or packets destined to the switch itself. Enabling IP traffic export (NetFlow) on the switch allows the administrator to analyze traffic flows and identify the specific source/destination IP addresses, ports, and protocols consuming CPU cycles, without overwhelming the CPU further. NetFlow provides granular visibility into the types of packets being processed, making it the correct tool for this scenario.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
Use extended ping from the switch to generate traffic.
Why it's wrong here
Option B is wrong because ping generates new traffic, not analyzing existing CPU-bound packets.
✗
Configure a SPAN session to capture all traffic to the CPU.
Why it's wrong here
Option A is wrong because SPAN mirrors traffic but does not isolate the specific packets causing high CPU.
✗
Check CDP neighbors to see if any devices are flooding.
Why it's wrong here
Option D is wrong because CDP is a Layer 2 protocol and not related to IP process CPU usage.
✓
Enable IP traffic export (NetFlow) on the switch.
Why this is correct
Option C is correct because NetFlow can identify the flows that are being processed by the CPU.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse SPAN (traffic mirroring) with a diagnostic tool, but SPAN does not provide built-in traffic analysis and can worsen CPU load, whereas NetFlow is designed for flow-level analysis without adding significant overhead.
Detailed technical explanation
How to think about this question
NetFlow (or IP traffic export) on Catalyst switches samples or exports flow records that include key fields like source/destination IP, ports, protocol, and packet counts, allowing the administrator to pinpoint traffic patterns such as a DoS attack or a misconfigured device flooding the CPU with packets. The 'IP Input' process handles packets that require process switching, such as those with IP options, TTL expiry, or destined to the switch's own IP address, which are often the culprits in high CPU scenarios. In a real-world scenario, a single host sending a high rate of SNMP or SSH packets to the switch could cause this, and NetFlow would reveal the offending host immediately.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
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.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Network Assurance — This question tests Network Assurance — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Enable IP traffic export (NetFlow) on the switch. — The 'IP Input' process handles incoming IP packets that require CPU processing, such as routing protocol updates, management traffic, or packets destined to the switch itself. Enabling IP traffic export (NetFlow) on the switch allows the administrator to analyze traffic flows and identify the specific source/destination IP addresses, ports, and protocols consuming CPU cycles, without overwhelming the CPU further. NetFlow provides granular visibility into the types of packets being processed, making it the correct tool for this scenario.
What should I do if I get this 350-401 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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