What is a common risk when the native VLAN is misconfigured across a trunk link?

What is a common risk when the native VLAN is misconfigured across a trunk link?

• A. Untagged frames may be delivered to the wrong VLAN
• B. The trunk will stop transmitting data
• C. All frames become tagged
• D. No risk; VLANs are independent

Answer: (A)

On an 802.1Q trunk, frames for most VLANs are tagged, but the native VLAN’s frames are sent untagged. If the native VLAN is configured differently on each end of the trunk, each switch will treat untagged frames as belonging to its own native VLAN. That means untagged frames from one side can be placed into the other side’s VLAN, causing traffic to be delivered to the wrong VLAN. This misdelivery can lead to traffic leakage, security concerns, and unpredictable network behavior. The other options don’t fit: the trunk isn’t guaranteed to stop transmitting just because the native VLAN is misconfigured; the native VLAN frames remain untagged, not all frames becoming tagged; and VLANs on a trunk aren’t immune from misrouting when native VLAN settings don’t match.

On an 802.1Q trunk, frames for most VLANs are tagged, but the native VLAN’s frames are sent untagged. If the native VLAN is configured differently on each end of the trunk, each switch will treat untagged frames as belonging to its own native VLAN. That means untagged frames from one side can be placed into the other side’s VLAN, causing traffic to be delivered to the wrong VLAN. This misdelivery can lead to traffic leakage, security concerns, and unpredictable network behavior.

The other options don’t fit: the trunk isn’t guaranteed to stop transmitting just because the native VLAN is misconfigured; the native VLAN frames remain untagged, not all frames becoming tagged; and VLANs on a trunk aren’t immune from misrouting when native VLAN settings don’t match.