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350-401 Practice Question: Which two statements about VLAN trunking using…
Which two statements about VLAN trunking using IEEE 802.1Q are true? (Choose two.)
⚠ Common exam trap
The trap is confusing 802.1Q with 802.1ad (0x88A8 vs 0x8100) and miscounting the VLAN range as 4096 instead of 4094 usable VLANs.
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 802.1Q tag includes a 12-bit VLAN ID field.
Option A is correct because the IEEE 802.1Q tag contains a 12-bit VLAN Identifier (VID) field, which allows VLAN IDs from 0 to 4095 (with 0 and 4095 reserved), giving 4094 usable VLANs. Option B is correct because on an 802.1Q trunk, frames belonging to the native VLAN are transmitted untagged, while all other VLAN frames carry the 4-byte tag. Option C is incorrect because the native VLAN is configurable and does not have to be VLAN 1, though VLAN 1 is the default. Option D is incorrect because 802.1Q uses a TPID value of 0x8100, whereas 0x88A8 is associated with 802.1ad (QinQ/Provider Bridging). Option E is incorrect because 802.1Q's 12-bit VID field supports 4096 possible values (4094 usable), not a maximum of 4096 usable VLANs as commonly misstated.
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 802.1Q tag includes a 12-bit VLAN ID field.
Why this is correct
The 802.1Q tag inserts a 12-bit VLAN Identifier field, allowing 4094 usable VLANs per trunk. This directly satisfies the question's requirement by confirming the tag's defined structure, distinguishing it from ISL's 15-bit field and enabling standard-based multi-vendor trunking.
- ✓
The native VLAN is not tagged on an 802.1Q trunk.
Why this is correct
On an 802.1Q trunk, frames belonging to the native VLAN traverse untagged, while all other VLANs carry the four-byte tag. This satisfies the scenario by describing default tag behaviour, which matters because mismatched native VLANs cause traffic leakage between switches.
- ✗
The native VLAN must always be VLAN 1.
Why it's wrong here
802.1Q permits any VLAN as the native VLAN, configured per trunk; frames there traverse untagged. It tempts because VLAN 1 is the default native VLAN on many switches, so the default is mistaken for a mandate.
- ✗
The 802.1Q tag uses a TPID value of 0x88A8.
Why it's wrong here
The 802.1Q tag's TPID is 0x8100; 0x88A8 identifies the outer tag in 802.1ad provider bridging (Q-in-Q). The option is tempting because 0x88A8 does appear in VLAN-tagged frames, but only where service providers stack customer tags, not in standard 802.1Q trunking between switches.
- ✗
802.1Q supports a maximum of 4096 VLANs.
Why it's wrong here
802.1Q's 12-bit VLAN identifier field permits 4094 usable VLAN IDs, since 0 and 4095 are reserved, so the 4096 figure is wrong. It tempts because the field width genuinely is 12 bits, and candidates who forget the two reserved values, or who conflate the theoretical bit count with the usable range, select it.
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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
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