350-401 Architecture Practice Question
A network administrator is deploying a new Cisco Catalyst switch in a campus network. The administrator wants to enable a feature that automatically assigns a voice VLAN to Cisco IP phones connected to the switch, based on CDP or LLDP information. Which feature should be configured?
⚠ Common exam trap
It's easy for candidates to confuse VLAN management protocols like VTP with endpoint-specific VLAN assignment features like Voice VLAN.
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
✓
Voice VLAN
The Voice VLAN feature allows a switch to automatically assign a VLAN to Cisco IP phones using CDP or LLDP. When a phone is detected, the switch instructs the phone to tag voice traffic with the voice VLAN ID. This separates voice and data traffic, enabling QoS and security policies. The other options are unrelated to automatic voice VLAN assignment.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
VLAN Trunking Protocol
Why it's wrong here
VLAN Trunking Protocol (VTP) is used to propagate VLAN configuration across switches. It does not assign voice VLANs to phones. VTP manages VLAN databases, but the automatic assignment of a voice VLAN to an endpoint is a separate feature.
- ✓
Voice VLAN
Why this is correct
Voice VLAN is a Cisco feature that automatically assigns a VLAN to IP phones based on CDP or LLDP discovery. The switch detects the phone and places its voice traffic in the configured voice VLAN, while data traffic from a connected PC remains in the access VLAN. This simplifies deployment and ensures QoS for voice.
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Private VLAN
Why it's wrong here
Private VLANs are used to isolate ports within a VLAN, typically in service provider or DMZ environments. They do not automatically assign a voice VLAN to IP phones. They restrict layer 2 connectivity between ports, which is not the goal here.
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Dynamic ARP Inspection
Why it's wrong here
Dynamic ARP Inspection (DAI) is a security feature that validates ARP packets to prevent ARP spoofing. It does not assign VLANs to IP phones. While it can be part of a secure campus design, it is unrelated to automatic voice VLAN assignment based on CDP or LLDP.
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JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official Cisco exam blueprint
This 350-401 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 350-401 exam.