The answer is to configure the global command 'snmp-server trap-source Loopback0'. This is correct because, by default, SNMPv2c traps use the IP address of the egress interface—the interface the router or switch uses to reach the NMS—which in this scenario is the management VLAN 1 interface. The 'snmp-server trap-source' command overrides this behavior by forcing all SNMP notifications to originate from a specified interface, ensuring the loopback IP is used as the source regardless of the routing path. On the ENCOR 350-401 exam, this tests your understanding of SNMP configuration and the distinction between reachability and source address selection; a common trap is assuming the 'snmp-server host' command alone controls the source IP. Remember the mnemonic: "Traps take the exit, unless you set the source."
350-401 SNMP and Syslog Practice Question
This 350-401 practice question tests your understanding of snmp and syslog. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. 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 engineer configures SNMPv2c on a Cisco switch to send traps to an NMS. The engineer uses 'snmp-server community public RO' and 'snmp-server host 10.1.1.1 version 2c public'. The NMS receives traps, but the engineer notices that the traps contain the IP address of the management interface (VLAN 1) instead of the loopback interface (Loopback0) that is used for management. The engineer wants the traps to use the loopback IP as the source. What should the engineer do?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Configure 'snmp-server trap-source Loopback0'.
The source IP of SNMP traps is determined by the interface used to reach the destination. To force a specific source IP, the engineer must configure 'snmp-server trap-source Loopback0'.
Key principle: A trunk being up does not mean the VLAN is allowed across it. Always verify the allowed VLAN list and whether the VLAN exists on both switches.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
Incorrect because the correct command is 'snmp-server trap-source'.
✓
Configure 'snmp-server trap-source Loopback0'.
Why this is correct
Correct because this command sets the source IP for all SNMP traps to the loopback interface.
Related concept
Access ports place end devices into a single VLAN.
✗
Configure 'ip snmp source-interface Loopback0'.
Why it's wrong here
Incorrect because this is not a valid Cisco command.
✗
Change the management interface IP to match the loopback.
Why it's wrong here
Incorrect because that would be inefficient and not a proper solution.
Common exam traps
Common exam trap: an active trunk can still block the VLAN you need
A trunk being up does not prove every VLAN is crossing it. Check allowed VLAN lists, native VLAN mismatch, VLAN existence and access-port assignment.
Trap categories for this question
Command / output trap
Incorrect because the correct command is 'snmp-server trap-source'.
Detailed technical explanation
How to think about this question
VLAN questions usually combine access-port and trunking clues. The key is to identify whether the issue is local to one switchport, caused by the trunk, or caused by the VLAN not existing where it needs to exist.
KKey Concepts to Remember
Access ports place end devices into a single VLAN.
Trunk ports carry multiple VLANs between switches.
Allowed VLAN lists decide which VLANs can cross a trunk.
Native VLAN mismatch can create confusing symptoms.
TExam Day Tips
→Use show vlan brief to verify access VLANs.
→Use show interfaces trunk to verify trunk state and allowed VLANs.
→Do not treat every same-VLAN issue as a routing problem.
Key takeaway
A trunk being up does not mean the VLAN is allowed across it. Always verify the allowed VLAN list and whether the VLAN exists on both switches.
Real-world example
How this comes up in practice
A help-desk technician troubleshoots why a newly connected PC cannot reach shared printers on the same floor. The cable is good, the switch port is active, but the PC is in VLAN 20 and the printers are in VLAN 10. The uplink trunk only allows VLAN 10. A trunk being up does not mean every VLAN crosses it.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this 350-401 question in full detail.
Review VLAN allowed lists, native VLAN mismatch detection, and how to verify VLAN membership with show vlan brief and show interfaces trunk. Then practise related 350-401 questions on switching, trunking, and access-port configuration.
SNMP and Syslog — This question tests SNMP and Syslog — Access ports place end devices into a single VLAN..
What is the correct answer to this question?
The correct answer is: Configure 'snmp-server trap-source Loopback0'. — The source IP of SNMP traps is determined by the interface used to reach the destination. To force a specific source IP, the engineer must configure 'snmp-server trap-source Loopback0'.
What should I do if I get this 350-401 question wrong?
Review VLAN allowed lists, native VLAN mismatch detection, and how to verify VLAN membership with show vlan brief and show interfaces trunk. Then practise related 350-401 questions on switching, trunking, and access-port configuration.
What is the key concept behind this question?
Access ports place end devices into a single VLAN.
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