CCNP Infrastructure Practice Question
A network engineer is deploying a new Cisco Catalyst switch and must ensure that the management VLAN 50 is the only VLAN allowed on the trunk link to the distribution switch, while also ensuring that the native VLAN matches on both ends. The distribution switch is already configured with switchport trunk native vlan 999 and switchport trunk allowed vlan 50. Which configuration on the new switch will satisfy these requirements?
⚠ Common exam trap
The trap here is overlooking the native VLAN mismatch that occurs if the native VLAN is not explicitly set to 999, or assuming that dynamic trunking will always form a trunk with a statically configured peer.
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
✓
interface GigabitEthernet0/1 switchport mode trunk switchport trunk native vlan 999 switchport trunk allowed vlan 50
To match the distribution switch, the new switch must be configured as a static trunk with native VLAN 999 and allowed VLAN 50. This ensures native VLAN consistency and restricts the trunk to only the management VLAN, preventing unnecessary traffic and security risks.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
interface GigabitEthernet0/1 switchport mode dynamic desirable switchport trunk native vlan 999 switchport trunk allowed vlan 50
Why it's wrong here
Dynamic desirable mode attempts to negotiate a trunk, but if the distribution switch is set to trunk mode (not auto or desirable), the link may not become a trunk. Also, dynamic mode can introduce negotiation delays. The requirement is a deterministic trunk, so static trunk mode is preferred.
- ✓
interface GigabitEthernet0/1 switchport mode trunk switchport trunk native vlan 999 switchport trunk allowed vlan 50
Why this is correct
This configuration sets the port as a trunk, matches the native VLAN to 999, and restricts allowed VLANs to 50. It aligns with the distribution switch configuration, ensuring native VLAN consistency and limiting traffic to the management VLAN. This meets both requirements exactly.
- ✗
interface GigabitEthernet0/1 switchport mode trunk switchport trunk native vlan 50 switchport trunk allowed vlan 50
Why it's wrong here
Although allowed VLANs are restricted to 50, the native VLAN is set to 50 instead of 999. A native VLAN mismatch with the distribution switch causes VLAN hopping risk and generates CDP/STP warnings. The requirement specifies matching native VLANs, so this is incorrect.
- ✗
interface GigabitEthernet0/1 switchport mode trunk switchport trunk allowed vlan 50 switchport trunk native vlan 1
Why it's wrong here
The native VLAN is left at the default of 1, which does not match the distribution switch's native VLAN 999. This mismatch can cause spanning-tree inconsistencies and potential security issues. The allowed VLAN is correct, but the native VLAN requirement is not met.
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.