You are the network administrator at Company and switch R1 is configured as shown below:

interface GigabitEthernet0/1
switchport mode trunk
switchport trunk encapsulation dot1q
switchport trunk native vlan 5

If untagged frames are arriving on interface GigabitEthernet0/1 of R1, which of the following statement are correct?

A.
Untagged frames are automatically assumed to be in VLAN 5.

B.
Untagged frames are defaulted to VLAN 1 traffic.

C.
Untagged frames are dropped because all packets are tagged when dot1q trunked.

D.
Untagged frames are determined on the other switch

E.
Untagged frames are not supported on 802.1Q trunks.

Explanation:

Each physical port has a parameter called PVID. Every 802.1Q port is assigned a PVID value that is of its native VLAN ID (default is VLAN 1). All untagged frames are assigned to the LAN specified in the PVID parameter. When a tagged frame is received by a port, the tag is respected. If the frame is untagged, the value contained in the PVID is considered as a tag. All untagged frames will be assigned to the native VLAN. The native VLAN is 1 by default, but in this case the native VLAN is configured as VLAN 5 so choice A is correct.