What is the function of the command switchport trunk native vlan 999 on a Cisco Catalyst switch?
A. It designates VLAN 999 for untagged traffic.
B. It blocks VLAN 999 traffic from passing on the trunk
C. It creates a VLAN 999 interface.
D. It designates VLAN 999 as the default for all unknown tagged traffic.
Correct Answer: A