CCNP Infrastructure Practice Question
A network engineer is configuring a Cisco Catalyst switch port that connects to an IP phone. The phone must place voice traffic in VLAN 200 and data traffic from a daisy-chained PC in VLAN 100. The switch port is currently configured as a static access port in VLAN 100. Which configuration must the engineer apply to meet these requirements?
⚠ Common exam trap
The trap here is assuming that a trunk must be configured to separate voice and data traffic, when the voice VLAN feature on an access port already handles this automatically.
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
✓
Configure the interface with the switchport voice vlan 200 command while leaving the access VLAN as 100.
The voice VLAN feature on a Cisco access port allows a phone to send tagged voice frames while data frames from a daisy-chained PC remain untagged in the access VLAN. Configuring the port with switchport voice vlan 200 and leaving it as an access port in VLAN 100 provides the required separation without manual trunk configuration.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Configure the interface as a dynamic auto trunk and set the voice VLAN to 200 with the switchport voice vlan command.
Why it's wrong here
Dynamic auto trunking does not form a trunk unless the neighbor actively initiates it. An IP phone typically does not initiate trunk negotiation with the switch; it relies on the voice VLAN feature. Mixing dynamic trunking with the voice VLAN command is unnecessary and can lead to inconsistent operation. The port should remain in access mode with the voice VLAN feature enabled.
- ✗
Configure the interface as a trunk, set the native VLAN to 200, and allow VLANs 100 and 200 on the trunk.
Why it's wrong here
Using a trunk with native VLAN 200 would send untagged traffic into VLAN 200, which is not appropriate for a voice VLAN deployment. The standard voice VLAN feature is designed to keep the data VLAN untagged and tag only voice frames, and it also allows the phone to learn the voice VLAN via LLDP-MED. This configuration would not provide the expected behavior for the attached phone and PC.
- ✓
Configure the interface with the switchport voice vlan 200 command while leaving the access VLAN as 100.
Why this is correct
The switchport voice vlan command enables the voice VLAN feature on an access port. Data frames from the PC remain untagged in the access VLAN (100), while voice frames from the phone are tagged with VLAN 200. The phone can also receive the voice VLAN assignment through LLDP-MED or CDP, making this the correct and simplest solution for a phone-plus-PC topology.
- ✗
Configure the interface as a trunk, set the native VLAN to 100, and allow only VLAN 200 on the trunk.
Why it's wrong here
This would prevent data traffic in VLAN 100 from being carried because VLAN 100 is not allowed on the trunk, and it would also drop untagged data frames since the native VLAN is 100 but that VLAN is not allowed. The voice VLAN feature is the intended mechanism for this scenario, not a manually pruned trunk. The PC would lose network connectivity.
Visual reference
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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.