hardMultiple Choice
300-410 Practice Question: Router R6 is configured to send SNMP inform…
Router R6 is configured to send SNMP inform requests to the NMS at 192.168.1.1. Configuration: snmp-server host 192.168.1.1 informs version 2c public, snmp-server enable traps. The NMS receives no informs. R6's show snmp statistics shows InformRequestsSent: 0, and show snmp pending shows no pending. The NMS can poll R6 successfully. The network has a firewall between R6 and the NMS that allows UDP 162. What is the root cause?
⚠ Common exam trap
Cisco often tests the misconception that the 'informs' keyword can be used with SNMPv2c because the CLI accepts the command without error, but the router will never actually send informs under v2c.
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
✓
The 'snmp-server host' command for informs requires the 'informs' keyword to be placed correctly, but the router may not support informs with v2c; informs are only supported with SNMPv3.
SNMPv2c does not support informs; informs require SNMPv3 because they need acknowledgment (response) from the NMS, which is only defined in SNMPv3. The 'snmp-server host' command with the 'informs' keyword will be accepted syntactically on a router running v2c, but the router will never actually send informs because the underlying protocol does not support the acknowledgment mechanism. This explains why InformRequestsSent remains 0 and no pending informs exist, even though the NMS can be polled successfully.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
The 'snmp-server host' command for informs requires the 'informs' keyword to be placed correctly, but the router may not support informs with v2c; informs are only supported with SNMPv3.
Why this is correct
SNMPv2c supports only traps, which are unacknowledged notifications; informs require an acknowledgment and are defined only for SNMPv3. Even if the 'informs' keyword were correctly placed in the 'snmp-server host' command, the v2c community configuration would make the router fall back to traps or generate an error, resulting in zero informs sent. The observed no-informs behavior is therefore the expected consequence of using v2c with an informs configuration.
- ✗
The NMS is not configured to send SNMP responses to informs.
Why it's wrong here
The NMS's ability to respond to informs only matters after the router has sent an inform and waits for an acknowledgment. The statistics show zero informs transmitted, meaning the router never even attempted to send a single inform. If the NMS were not configured to reply, the router would show informs sent with no acknowledgments received, not zero sends. Thus this cannot explain the observed counter.
- ✗
The firewall is blocking UDP 162 from the NMS to the router.
Why it's wrong here
Informs are sent by the router to the NMS with destination UDP port 162, while the NMS's acknowledgment returns to a dynamic source port used by the router. A firewall rule blocking UDP 162 from the NMS to the router would prevent that inbound response, but it would not stop the router from transmitting the initial inform. Since the router's inform counter is zero, the failure occurs before any packet leaves the router, so the firewall is not the root cause.
- ✗
The router's SNMP agent is not enabled due to a missing 'snmp-server' command.
Why it's wrong here
The SNMP agent is already enabled because the configuration includes 'snmp-server enable traps' and a valid 'snmp-server host' entry, both of which initialize the agent. A missing 'snmp-server' command would leave the agent disabled entirely, but here the agent is operational and could send traps if configured. Also, the issue is specific to informs not being sent while traps likely are, indicating the agent is active. Hence this option is incorrect.
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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.