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hardMultiple ChoiceObjective-mapped

EEM CoPP and uRPF Drop syslog — Missing Log Keyword

An engineer configures an EEM applet to monitor CoPP (Control Plane Policing) drops using the event syslog pattern 'COPP-3-DROP'. The applet is intended to log when CoPP drops packets. The CoPP policy is applied with a rate-limit in bps, but the traffic exceeds the rate, and packets are dropped. The EEM applet does not trigger. Which is the most likely explanation?

Quick Answer

The answer is that the CoPP policy must include the **log** keyword for individual drops to generate a syslog message, without which the EEM applet monitoring the 'COPP-3-DROP' pattern will never trigger. CoPP suppresses per-packet syslog generation by default to prevent CPU overload; the **COPP-3-DROP** message only appears when the drop rate crosses a built-in threshold or when the **log** keyword is explicitly added to the **police** command in the policy-map. On the Cisco CCNP ENARSI 300-410 exam, this question tests your understanding that EEM event syslog triggers depend entirely on the underlying feature generating the log—CoPP does not log every drop, and **uRPF** drops similarly require explicit logging configuration. A common trap is assuming any drop automatically produces a syslog, but the reality is that both CoPP and uRPF drops are silent unless logging is enabled. Memory tip: “No log, no log—CoPP drops stay quiet without the keyword.”

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

✓

CoPP does not generate syslog messages for individual drops unless the 'log' keyword is configured in the policy.

CoPP generates syslog messages only when the drop rate exceeds a certain threshold or when the policy is applied, not for every individual drop. By default, CoPP does not generate syslog messages for every dropped packet because it would overwhelm the router. The 'COPP-3-DROP' syslog is generated only if the 'police' action includes the 'log' keyword or if the drop rate is significant enough to trigger a log. Without explicit logging configuration in the CoPP policy, no syslog is generated, and the EEM applet will not trigger.

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

  • ✓

    CoPP does not generate syslog messages for individual drops unless the 'log' keyword is configured in the policy.

    Why this is correct

    Correct. CoPP drops are not logged by default; the 'log' keyword must be added to the police action.

  • ✗

    The EEM applet must use 'event class-map' to capture CoPP events.

    Why it's wrong here

    EEM does not have a native class-map event trigger.

  • ✗

    The rate-limit in bps is incorrect; it should be in pps to generate syslog.

    Why it's wrong here

    The rate-limit unit does not affect syslog generation.

  • ✗

    The CoPP policy must be applied to the input direction only for drops to be logged.

    Why it's wrong here

    Direction does not affect whether drops are logged.

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Same concept, more angles

1 more way this is tested on 300-410

These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.

Variation 1. A network engineer configures an EEM applet to monitor uRPF (Unicast Reverse Path Forwarding) failures using the event syslog pattern 'IP-3-URPF'. The applet is designed to log when uRPF drops packets due to strict mode. The network has asymmetric routing, and packets are dropped. The EEM applet does not trigger. Which is the most likely explanation?

hard
  • ✓ A.uRPF strict mode drops packets silently without generating a syslog message unless the 'log' keyword is used.
  • B.The EEM applet must use 'event routing' to capture uRPF events.
  • C.Asymmetric routing causes uRPF to generate a different syslog pattern, such as 'IP-4-URPF'.
  • D.The uRPF must be configured in loose mode to generate syslog messages.

Why A: uRPF strict mode drops packets when the source IP address is not reachable via the incoming interface. However, the syslog message 'IP-3-URPF' is generated only when the 'ip verify unicast source reachable-via' command is configured with the 'allow-default' option or when the drop is logged explicitly. In strict mode without 'allow-default', the router may drop packets silently without generating a syslog message, especially if the drop is due to asymmetric routing. The EEM applet will not trigger because no syslog is generated for the drop.

JA

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.