问题
单项选择题
In (66) the strength of the carrier signal is varied to represent binary 1 or 0. (67) is a system that can map a name to an address and conversely an address to al name. (68) is a three-way handshaking authentication protocol that it’s packets are encapsulated in the point-to-point protocol. (69) is an approach that enables an ATM switch to behave like a LAN switch. (70) is an guided media which is made of glass or plastic and transmits signals in the form of light.
A．NAT
B．NCP
C．DDN
D．DNS
答案
参考答案：D
解析：本题主要考查域名系统的缩写DNS。NAT是Network能Address Translation的缩写。NCP是Network Core protocol的缩写。DDN是Digital Data Network的缩写。答案为D。