单项选择题
A.Cisco ISL B.IEEE 802.1Q C.IEEE 802.3 D.IEEE 802.11
A.255.255.255.0 B.255.255.248.0 C.255.255.252.0 D.255.255.0.0
A.6芯短屏蔽铜缆 B.8芯STP C.单模光缆 D.8芯UTP