Quick Answer
The correct configuration is to set the switchport as a trunk port. This is because a trunk port uses IEEE 802.1Q encapsulation to tag frames with VLAN IDs, allowing a single physical link to carry traffic for multiple VLANs to a router, which is the foundational concept of a router-on-a-stick topology. On the ENCOR 350-401 exam, this tests your understanding of Layer 2 switching and inter-VLAN routing; a common trap is confusing an access port, which only carries a single untagged VLAN, with a trunk port. Remember the key distinction: access ports are for endpoints, trunk ports are for infrastructure links like routers and switches. A simple memory tip is "Trunk for Transport" — if you need to transport multiple VLANs over one cable, you must trunk it.
This 350-401 practice question tests your understanding of infrastructure. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
An engineer needs to configure a switchport to carry traffic for multiple VLANs to a router using a single physical link. Which configuration should be applied on the switchport?
Configure the port as a dynamic desirable port.
Why wrong: Dynamic desirable is a DTP mode, not a trunk.
Configure the port as a trunk port.
Trunk ports carry multiple VLANs.
Configure the port as a routed port.
Why wrong: Routed ports are Layer 3 interfaces.
Configure the port as an access port.
Why wrong: Access ports carry only one VLAN.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
Configure the port as a trunk port.
Option B is correct because a trunk port is specifically designed to carry traffic for multiple VLANs over a single physical link using IEEE 802.1Q encapsulation. This allows the switch to tag frames with VLAN IDs, enabling the router (often configured as a router-on-a-stick) to route between VLANs.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
Configure the port as a dynamic desirable port.
Configure the port as a trunk port.
Why this is correct
Trunk ports carry multiple VLANs.
Related concept
Read the scenario before looking for a memorised answer.
Configure the port as a routed port.
Why it's wrong here
Routed ports are Layer 3 interfaces.
Configure the port as an access port.
Why it's wrong here
Access ports carry only one VLAN.
Common exam traps
The trap here is that candidates often confuse Dynamic Desirable (a DTP negotiation mode) with a trunk port configuration, thinking negotiation automatically results in trunking, but the question asks for the configuration that directly enables multi-VLAN traffic, not a negotiation protocol.
Detailed technical explanation
When a trunk port is configured, it uses 802.1Q tagging to insert a 4-byte VLAN tag into Ethernet frames, allowing the switch to multiplex traffic from multiple VLANs over the same link. A common real-world scenario is a router-on-a-stick configuration where the router's subinterfaces (e.g., GigabitEthernet0/0.10, GigabitEthernet0/0.20) are mapped to specific VLANs, and the switchport trunk must allow those VLANs using the 'switchport trunk allowed vlan' command.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
A help-desk technician troubleshoots why a newly connected PC cannot reach shared printers on the same floor. The cable is good, the switch port is active, but the PC is in VLAN 20 and the printers are in VLAN 10. The uplink trunk only allows VLAN 10. A trunk being up does not mean every VLAN crosses it.
What to study next
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FAQ
Infrastructure — This question tests Infrastructure — Read the scenario before looking for a memorised answer..
The correct answer is: Configure the port as a trunk port. — Option B is correct because a trunk port is specifically designed to carry traffic for multiple VLANs over a single physical link using IEEE 802.1Q encapsulation. This allows the switch to tag frames with VLAN IDs, enabling the router (often configured as a router-on-a-stick) to route between VLANs.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 11, 2026
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