题目内容
Microwave communication uses(66)-frequency radio waves that travel in straightline sthrough the air. Because the waves cannot(67)with the curvature of the earth, they can be(68)only over short distance. Thus, microwave is a good(69)for sending data between buildings in a city or on a large college campus. For longer distances, the waves must be relayed by means of" dishes" or(70). These can be installed on towers, highbuildings, and mountain tops.
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In the strength of the carrier signal is varied to represent binary 1 or 0.
(72) is a system that can map a name to an 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 signals in the form. of light.
A．物理层、数据链路层、网络层B．物理层、数据链路层、传输层C．物理层、网络层、表示层D．物理层、传
A．touch/var/state/dhcp/dhcpd.1easesB．address/var/state/dhcp/dhcpd.1easesC．nat/var/stat
A．手写签名B．数据完整性机制C．数字签名机制D．加密机制
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