What is the function of the command switchport trunk native vlan 150 on the Cisco Catalyst Switch?
A. It creates a VLAN 150 interface
B. It designates VLAN 150 for untagged traffic
C. It blocks VLAN 150 traffic from passing on the trunk
D. It designates VLAN 150 as the default for all unknown tagged traffic.
Answer: B
Explanation:
In 802.1Q trunking, all VLAN packets are tagged on the trunk link to indicate the VLAN to which they belong. Frames belonging to the Native VLAN are sent untagged on the trunk link. The Native VLAN contains ports not assigned to other VLANs that by default belong to VLAN 1. VLAN 1 is the Native VLAN by default, but VLANs other than VLAN 1 may be designated as the Native VLAN. However, the Native VLAN must be the same on trunked switches in 802.1Q trunking. If a VLAN other than VLAN 1 is to be the Native VLAN, it needs to be identified on the trunk ports. In the interface configuration mode of the trunk port(s), the IOS-based command to designate the Native VLAN is switchporttrunk native.
Switch(config-if)#switchport trunk native vlan vlan-id
The switchporttrunk native vlan command is only necessary when changing the native VLAN from something other than VLAN 1 or changing it back to VLAN 1.