Refer to the exhibit. A network engineer changes the default native VLAN to VLAN 999. After applying the settings on the uplinks to the core switches, the switch control traffic, such as CDP and VTP, is no longer working. The standard configuration is used for each uplink.
What is wrong with the configuration?
A. The interface is administratively down.
B. The encapsulation type is incorrect.
C. The switchport mode trunk command should be first in the output.
D. The native VLAN is not present on the trunk.
E. The control traffic must be manually enabled on the new native VLAN.
