JN0-106 Networking Fundamentals Practice Question
You are configuring a Juniper EX Series switch port that connects to an IP phone. The phone must tag its voice traffic in VLAN 30, while an attached PC sends untagged traffic that should be placed in VLAN 20. You want to configure the port so that both traffic types are accepted on the same physical interface. Which port mode should you configure?
⚠ Common exam trap
The trap here is assuming that an access port can process tagged frames or that a trunk port automatically accepts all VLANs without explicit membership.
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
✓
trunk mode with native-vlan-id 20 and VLAN 30 as a member
A trunk port can carry multiple VLANs, with the native VLAN handling untagged frames and other VLANs handling tagged frames. Setting the native VLAN to 20 places untagged PC traffic correctly, while including VLAN 30 as a member allows the phone's tagged voice traffic. This is the correct way to support both devices on one switch port.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
access mode with vlan-id 30
Why it's wrong here
Access mode does not process 802.1Q tags, so the phone's tagged frames would be dropped. Even if untagged traffic were assigned to VLAN 30, the PC data would be placed in the voice VLAN, which is incorrect. This configuration fails to separate voice and data traffic as required.
- ✓
trunk mode with native-vlan-id 20 and VLAN 30 as a member
Why this is correct
A trunk port with native-vlan-id 20 accepts untagged PC frames and places them in VLAN 20. Adding VLAN 30 as a member allows the port to accept the phone's tagged frames in VLAN 30. This configuration correctly supports both traffic types on the same physical interface, which is the standard VoIP deployment model.
- ✗
trunk mode with native-vlan-id 20
Why it's wrong here
Trunk mode carries multiple VLANs, but the native VLAN applies to untagged frames. Configuring native-vlan-id 20 would place untagged PC traffic into VLAN 20, but the phone's tagged VLAN 30 traffic also requires explicit membership in VLAN 30. Without configuring the VLAN members, the tagged frames would not be accepted, so this alone is insufficient.
- ✗
access mode with vlan-id 20
Why it's wrong here
An access port accepts only untagged frames and assigns them to a single VLAN. It cannot accept tagged frames from the phone, so voice traffic in VLAN 30 would be dropped or misclassified. This does not meet the requirement of supporting both tagged voice and untagged data on the same physical interface.
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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 Juniper Networks exam blueprint
This JN0-106 practice question is part of Courseiva's free Juniper Networks 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 JN0-106 exam.