350-601 802.1Q tag Practice Question
A network engineer is configuring 802.1Q trunking between a Nexus switch and a server. Which TWO statements are true regarding 802.1Q trunking?
⚠ Common exam trap
Candidates often assume every frame on a trunk gets a 4-byte tag, but the native VLAN is always untagged. The question asks for two true statements; B and E are correct, and C is a common trap.
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 VLAN ID is 12 bits long
802.1Q trunking uses a 4-byte tag to carry VLAN information, but the native VLAN is sent untagged, so not all frames receive the tag. The VLAN ID field is 12 bits (B), and after tagging, the FCS must be recalculated (E). Option A is false because the native VLAN is untagged. Option C is false because only non-native VLAN frames are tagged. Option D is false because trunks can carry multiple VLANs.
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 native VLAN is tagged by default
Why it's wrong here
The native VLAN is not tagged; it is sent untagged.
- ✓
The VLAN ID is 12 bits long
Why this is correct
Correct — the VLAN ID field is 12 bits long.
- ✗
A 4-byte tag is inserted into the Ethernet frame
Why it's wrong here
Incorrect — not all frames receive a 4-byte tag; native VLAN frames are untagged.
- ✗
Trunks can only carry one VLAN
Why it's wrong here
Trunks can carry multiple VLANs, not just one.
- ✓
The frame check sequence (FCS) is recalculated after tagging
Why this is correct
Correct — the FCS is recalculated after the tag is inserted because the frame content changes.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This 350-601 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 350-601 exam.