問題文
An interface of a switch is written in the enterprise style, and the flexible encapsulation of Ethernet services is left off the physical port. On which units may the family that puts a unit into the second layer be written, and may an identifier of a VLAN be bound to the unit numbered zero?
選択肢
- It may be written on any unit the operator cares to number, and one identifier of a VLAN may be bound to the unit numbered zero, since a unit of that kind holds a single VLAN of its own and carries none of the frames that happen to arrive at that port with no tag at all upon any of them
- It may be written on the unit numbered zero and nowhere else, and one identifier of a VLAN may be bound to that unit, since a unit of that kind holds a single VLAN of its own and carries none of the frames that happen to arrive at that port with no tag at all upon any of them
- It may be written on any unit the operator cares to number, and no identifier of a VLAN may be bound to the unit numbered zero, because a unit of that kind keeps any single VLAN of its own out of the picture, running either as a trunk or as a carrier of frames that arrive with no tag on them
- It may be written on the unit numbered zero and nowhere else, and no identifier of a VLAN may be bound to that unit, because a unit of that kind keeps any single VLAN of its own out of the picture, running either as a trunk or as a carrier of frames that arrive with no tag on them