某数据的7位编码为0100011，若要增加一位奇校验位（最高数据位之前），则编码为（）。
A.11011100
B.01011100
C.10100011
D.00100011

在TCP/IP网络体系中，ICMP协议的作用是（39）。
A.ICMP用于从MAC地址查找对应的IP地址
B.ICMP把全局IP地址转换为私网中的专用IP地址
C.当IP分组传输过程中出现差错时通过ICMP发送控制信息
D.当网络地址采用集中管理方案时ICMP用于动态分配IP地址

Together with the network layer,the transport layer is the heart of the protocol ( ).The network layer provides end-to-end () delivery using datagrams or virtual circuits.The transport layer builds on the network layer to provide data transport from a process on a () machine to a process on a destination machine with a desired level of reliability that is independent of the physical (请作答此空) currently in use.It provides the abstractions that applications nedd to use the network..Without the () layer,the whole concept of layered protocols would make little sense.
A.traffic
B.connection
C.lines
D.networks

IP地址中，用于多播的是（）地址。
A.A类
B.B类
C.C类
D.D类

按照标准的（18），我国标准分为国家标准、行业标准、地方标准和企业标准四级。
A.分类原则
B.适用范围
C.性质
D.级别

In multipoint networks , there are tree persistence methods when a station finds a channel busy.in the 1-persistent method,after the station finds the line idle,it sends its frame immediately.this method has the （ ） chance of collision because two or more stations may find the line （ ） and send their frames immediately. In the nonpersistent method , a station that has a frame to send （ ） the line . If the line is idle , it sends immediately If the line is not idle , it waits a （ ） amount of time and then senses the line again.The nonpersistent approach （请作答此空） the chance of collision because it is unlikely that two or more stations will wait the same amount of time and retry to send simultaneously The p-persistent approach combines the advantages of the other two strategies . It reduces the chance of collision and improves efficiency.
A.increases
B.equalizes
C.reduces
D.cancels