hardMultiple ChoiceObjective-mapped
300-410 Practice Question: Configures SNMPv3 with authentication and privacy…
A network engineer configures SNMPv3 with authentication and privacy on a router. The NMS can poll the router successfully. After a router reload, the NMS fails to poll the router, but the SNMP configuration is unchanged. Which is the most likely explanation?
⚠ Common exam trap
Cisco often tests the subtle behavior that SNMPv3 keys are tied to the engine ID, and candidates mistakenly assume that unchanged SNMP configuration guarantees continued operation after a reload.
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 engine ID changed after the reload because it was not explicitly configured, causing authentication keys to be recalculated.
SNMPv3 uses the engine ID as a seed to generate authentication and privacy keys. If the engine ID is not explicitly configured, it is automatically derived from the router's MAC address or other unique identifier. After a reload, the engine ID may change (e.g., due to a different interface coming up first), causing the NMS to recalculate keys that no longer match the router's keys, breaking authentication even though the configuration appears unchanged.
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 engine ID changed after the reload because it was not explicitly configured, causing authentication keys to be recalculated.
Why this is correct
SNMPv3 keys are derived from the engine ID; if the engine ID changes, the NMS must be reconfigured with the new engine ID or the router must have a persistent engine ID configured.
- ✗
The router lost its SNMP configuration due to a failed startup config.
Why it's wrong here
The question states the configuration is unchanged, so the startup config is intact.
- ✗
The NMS's SNMPv3 credentials were deleted during the reload.
Why it's wrong here
The NMS is separate from the router and its configuration is not affected by the router reload.
- ✗
The router's SNMP process failed to start after reload.
Why it's wrong here
SNMP is typically integrated into the IOS and starts automatically; a failure would likely generate a syslog message.
Quick reference
Access Control Model Comparison
| Model | Acronym | Who Controls Access? | Best For |
|---|---|---|---|
| Discretionary Access Control | DAC | Resource owner | Small teams, file shares |
| Mandatory Access Control | MAC | System / security labels | Classified govt / military |
| Role-Based Access Control | RBAC | Administrator (via roles) | Enterprise environments |
| Attribute-Based Access Control | ABAC | Policy engine (user + resource attributes) | Fine-grained, dynamic policies |
| Rule-Based Access Control | RuBAC | System rules / ACLs | Firewall rules, network ACLs |
Go deeper
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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.