A.waveB.FrequencyC.codeD.spectrum

A.medium

B.frequency

C.modem

D.carrier

A.signal

B.wave

C.pulses

D.data

series of binary voltage (72) into an analog signal by encoding the digital data ontoa carrier frequency. The resulting signal occupies a certam spectrum of (73) centered about the carTier and may be propagated acrossa medium suitable for that carrier. The most common modems represent digital data in the voice(74)and hence allow those datato be propagated over ordinary voice-grade (75 )lines At the other end of the line, another modem demodulates the signal to recover the original data

(71)

A.analog

B.digital

C.Modem

D.electric

采用交叉双绞线连接的设备组合是(70)。

A.PC与PC

B.PC与交换机

C.交换机与路由器

D.PC与路由器

POP3服务默认的TCP端口号是(69)。

A.20

B.25

C.80

D.110

匿名FTP访问通常使用(68)作为用户名。

A.administrator

B.anonymous

C.user

D.guest

Windows XP系统中，管理权限最高的是用户组是(67)。

A.Administrators

B.Users

C.Guests

D.Power Users

命令可查看本机路由表。

A.arp-a

B.ping

C.route print

D.tracert

在Windows的命令行窗口中键入命令

这个命令序列的作用是 (65) 。

A.查询202. 30.192. 2的邮件服务器信息 ’

B.查询202.30.192.2到域名的映射

C.查询202.30.192.2的区域授权服务器

D.显示202 .30 .192. 2中各种可用的信息资源记录

在Lrnux操作系统中，DHCP服务默认的配置文件为(64)。

A./etc/sbin/dhcpd.conf

B./etc/dhcpd.conf

C./var/state/dhcp.config

D. /usr/sbin/dhcp.config