第12題： 下面關(guān)于路由器的描述中，正確的是（）。
A.路由器中串口與以太口必須是成對的
B.路由器中串口與以太口的IP地址必須在同一網(wǎng)段
C.路由器的串口之間通常是點對點連接
D.路由器的以太口之間必須是點對點連接
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第13題： PGP的功能中不包括（）。
A.郵件壓縮
B.發(fā)送者身份認(rèn)證
C.郵件加密
D.郵件完整性認(rèn)證
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第14題： 如果DHCP客戶端發(fā)現(xiàn)分配的IP地址已經(jīng)被使用，客戶端向服務(wù)器發(fā)出（）報文，拒絕該IP地址。
A.DHCP Release
B.DHCP Decline
C.DHCP Nack
D.DHCP Renew
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第1題： With circuit switching,a（71）path is established between two stations for communication.Switching and transmission resources within the networkare（72）for the exclusive use of the circuit for the duration of the connection.The connection is（73）：Once it is established，it appears to attached devices as if there were a direct connection.Packet switching was designed to provide a more efficient facility than circuit switching for（74）data traffic.Each packet contains some portion of the user data plus control information needed for proper functioning of the network.A key distinguishing element of packet-switching networks is whether the internal operation is datagram or virtual circuit.With internal virtual circuits,a route is defined between two endpoints and all packets for that virtual circuit follow the（75）route,With internal datagrams,each packet is treated independently,and packets intended for the same destination may follow different routes.
71、A.unique
B.dedicated
C.nondedicated
D.independent
72、A.discarded
B.abandoned
C.reserved
D.broken
73、A.indistinct
B.direct
C.indirect
D.transparent
74、A.casual
B.bursty
C.limited
D.abundant
75、A.same
B.different
C.single
D.multiple
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