赞题库-背景图
单项选择题

(71) in the strength ofthe carrier signal is varied to represent binary 1 or 0.
(72) is a system that can map a name to all address and conversely an address to an name.
(73) is a three-way handshaking authentication protocol that it’s packets are encapsulated in the point-to-point protocol
(74) is an approach that enables an ATM Switch to behave like a LAN switch.
(75) is an guided media which is made of glass or plastic and transmits signaIs in the form of light.

A.Coaxial cable
B.Optical fiber
C.Unshielded Twisted-pair Cable
D.Shielded Twisted-pair Cable