Chapter 1 Computer Networks and the Internet.doc

Chapter 1 Computer Networks and the Internet 1．The ( ) is a worldwide computer network, that is, a network that interconnects millions of computing devices throughout the world. ppt3 A public Internet 公共网络 B Intranet 企业内部互联网 C switch net 交换网 D television net 电视网 2．Which kind of media is not a guided media(引导媒体)? ( ) A twisted-pair copper wire 双绞线铜线 B a coaxial cable 同轴电缆 C fiber optics 纤维光学 D digital satellite channel 数字卫星频道 3．Which kind of media is a guided media? ( ) A geostationary satellite 地球同步卫星 B low-altitude satellite 低空卫星 C fiber optics 纤维光学 D wireless LAN 无线局域网 4．The units of data exchanged by a link-layer protocol are called ( ). A Frames B Segments C Datagrams D bit streams 5．Which of the following option belongs to the circuit-switched(电路交换) networks? ( ) A FDM B TDM C VC networks D both A and B 6．( )makes sure that neither side of a connection overwhelms the other side by sending too many packets too fast. A Reliable data transfer B Flow control C Congestion control D Handshaking procedure 8．Datagram networks and virtual-circuit networks differ in that ( ). A datagram networks are circuit-switched networks, and virtual-circuit networks are packet-switched networks. B datagram networks are packet-switched networks, and virtual-circuit networks are circuit-switched networks. C datagram networks use destination addresses and virtual-circuit networks use VC. numbers to forward packets toward their destination. D datagram networks use VC. numbers and virtual-circuit networks use destination addresses to forward packets toward their destination. 9．In the following options, which one is not a guided media? ( ) A twisted-pair wire B fiber optics C coaxia