在Windows操作环境中，如果想查看域名服务器是否工作正常，可以采用（）命令。
A. nslookup
B. tracert
C. netstat
D. nbtstat
Which of the following statements is NOT true（）
A. With VoIP technology, the phone caller's voice will be broken into pieces.
B. Different types of technology are accompanied with different advantages.
C. With VoIP technology, the quality of voice will always remain the same.
D. On the Internet, information will be broken into pieces and then connected again.
So far, how many volumes of the book have been published（）
A. Five.
B. Four.
C. Three.
D. None.
Which of the following will affect the voice quality through Internet（）
A. The speed of your voice.
B. The speed of the Internet.
C. The Internet traffic.
D. The service of the operator.
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