200-301 Question 201
Single answerA network administrator is troubleshooting an issue where untagged traffic is being dropped between two switches configured with 802.1Q trunk links. The switches are connected, and VLANs are correctly assigned to the trunk. What could be the reason for this issue?
- A
The native VLAN is mismatched between the two switches.
- B
The trunk port is not configured as an access port.
- C
The trunk link is not carrying all VLANs.
- D
802.1Q encapsulation is not enabled on the trunk port.
Show answer and explanation
Correct answer: A
Explanation
The native VLAN on a trunk link is used to handle untagged traffic. If the native VLANs are mismatched between two switches, each switch will interpret untagged traffic as belonging to a different VLAN, leading to dropped traffic. Ensuring the native VLAN is consistent across all switches in the network can prevent this issue.
- A. Correct.
A mismatch in the native VLAN configuration between two switches can cause untagged traffic to be dropped because each switch interprets the untagged traffic as belonging to its own native VLAN, leading to a mismatch and potential traffic loss.
- B. Incorrect.
Access ports are not used for trunk links. Trunk ports allow multiple VLANs to pass traffic, while access ports are used for endpoints in a single VLAN.
- C. Incorrect.
While it's important for the trunk link to carry the necessary VLANs, this issue specifically pertains to untagged traffic, which is handled by the native VLAN configuration.
- D. Incorrect.
802.1Q encapsulation is typically enabled automatically when a port is configured as a trunk. If it were not enabled, no VLAN traffic would pass, not just untagged traffic.