（ ） It is the WAN transmission technology after IP technology. It uses data label to guide data packet to transmit in open communication network with high speed and high efficiency, and introduces c

Most IP layer-based proxy mechanisms，such as network address translation (NAT)，only supportuni-directional proxy，from the internal network to external network(the Interned．The proxvestablishes the communication channel by (71) IP addresses．The IP addresses must be (72) ．These proxy mechanisms prevent applications that must establish return data channels from establishing their data channels，such as，multimedia applications．IP layer-based proxy mechanisms need additional software (73) for each application that uses (74) channels． SOCKS identifies communication targets through domain names，overcoming the restriction of Usina private IP addresses．SOCKS can use domain names to establish communication between separate LANs，with (75) IP addresses．

(66)

A．manufacturing

B．manipulating

C．conduct

D．implement

The high-speed data services for the interconnection of computer networks are usually referred to as ______ connections．

A．LANs

B．MANs

C．WANs

D．ATM

The approaching 4G mobile communication systems are projected to （ ） still remaining problems of 3G systems and to provide （ ） new services ,from high-quality voice to high-definition video to high data-rate wireless channels.[1分]

A.solve

B.solving

C.reduce

D.increase

A. X25

B. Frame Relay

C. ATM

D. ISDN

E. ATX

F. None of the above

For data transmission to be successful，sending and receiving devices must follow a set of communication rules for the exchange of information. These rules are known as（ ）.

A.E-mail B.Intemet C.network D.protocols

A typical application of this(71)is ADSL. It is emerging as the technology for home-and small-office Internet connectivity. It provides either 1.5 Mb/s～8 Mb/s from the network to the user and 64 Kb/s～512 Kb/s in the reverse direction depending on the distance, 12 000 or 18 000 feet.. The different speed for each direction gives it the(72)label. ADSL is designed to take advantage of the fact that video-on demand, telecommuting, and Internet access traffic are inherently asymmetrical. The user(73)a brief message up to the network and receives a ton of data coming back, either a movie or a piece of data download. Under such a scenario, low-speed traffic to the network is just fine. ADSL delivers high(74)where you need it and only uses a single copper pair. Through multiplexing, it also reserves(75)of the bandwidth for POTS.

A．FTTH

B．HFC

C．FTTC

D．HDSL

Microwave communication uses high-frequency(56)waves that travel in straightlines through the air. Because the waves cannot(57)with the curvature of the earth, they can be(58)only over short distance. Thus, microwave is a good(59)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(60).These can be installed on towers, high buildings, and mountain tops.

A．optical

B．radio

C．electrical

D．magnetic

A.Both technologies guarantee an identical copy of data on the secondary node

B.Only MySQL can maintain a time-delayed copy of data on the secondary node

C.Both technologies use the TCP/IP stack as their primary transmission medium

D.DRBD uses shared-disk technology

An IP ( ) is a unique number the computer uses to identify itself, and to be identified over a network.

A.address

B.device

C.point

D.data

A. Data, Frame, Packet, Segment, Bit

B. Data, Frame, Segment, Packet, Bit

C. Data, Packet, Frame, Segment, Bit

D. Data, Packet, Segment, Frame, Bit

E. Data, Segment, Frame, Packet, Bit

F. Data, Segment, Packet, Frame, Bit