📄 模拟考试19.htm
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A向B发送消息P，并使用公钥体制进行数字签名。另外报文中还加入了 (35) ，用于防止重发攻击(replay attack)。©) <BR>答：
<INPUT class=radio name=text1559 onblur="this.className='radio'"
onfocus="this.className='inputedit';this.select()" type=radio
value=A>A.伪随机数<BR> <INPUT class=radio name=text1559
onblur="this.className='radio'"
onfocus="this.className='inputedit';this.select()" type=radio
value=B>B.时间标记<BR> <INPUT class=radio name=text1559
onblur="this.className='radio'"
onfocus="this.className='inputedit';this.select()" type=radio
value=C>C.私有密钥<BR> <INPUT class=radio name=text1559
onblur="this.className='radio'"
onfocus="this.className='inputedit';this.select()" type=radio
value=D>D.数字签名<BR></TD></TR>
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<TD align=middle height=212 width=29>17 </TD>
<TD align=left height=212 width=607> IEEE802．11
MAC层具有多种功能，其中分布式协调功能采用的是 (43) 协议©) <BR>答： <INPUT class=radio
name=text1574 onblur="this.className='radio'"
onfocus="this.className='inputedit';this.select()" type=radio
value=A>A.CSMA／CA<BR> <INPUT class=radio name=text1574
onblur="this.className='radio'"
onfocus="this.className='inputedit';this.select()" type=radio
value=B>B.CSMA／CB<BR> <INPUT class=radio name=text1574
onblur="this.className='radio'"
onfocus="this.className='inputedit';this.select()" type=radio
value=C>C.CSMA／CD<BR> <INPUT class=radio name=text1574
onblur="this.className='radio'"
onfocus="this.className='inputedit';this.select()" type=radio
value=D>D.CSMAJCF<BR></TD></TR>
<TR class=trh1>
<TD align=middle height=212 width=29>18 </TD>
<TD align=left height=212 width=607> IEEE802．11
MAC层具有多种功能，用于支持多媒体应用的是 (44) 功能©) <BR>答： <INPUT class=radio
name=text1576 onblur="this.className='radio'"
onfocus="this.className='inputedit';this.select()" type=radio
value=A>A.BCF <BR> <INPUT class=radio name=text1576
onblur="this.className='radio'"
onfocus="this.className='inputedit';this.select()" type=radio
value=B>B.DCF<BR> <INPUT class=radio name=text1576
onblur="this.className='radio'"
onfocus="this.className='inputedit';this.select()" type=radio
value=C>C.PCF<BR> <INPUT class=radio name=text1576
onblur="this.className='radio'"
onfocus="this.className='inputedit';this.select()" type=radio
value=D>D.QCF<BR></TD></TR>
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<TD align=middle height=212 width=29>19 </TD>
<TD align=left height=212 width=607>
采用可变长子网掩码技术可以把大的网络分成小的子网，例如把子网掩码为255．255．0．0的网络40．15．0．0分为两个子网，假设第一个子网为40．15．0．0／17，则第二个子网为
(46) 。©) <BR>答： <INPUT class=radio name=text1578
onblur="this.className='radio'"
onfocus="this.className='inputedit';this.select()" type=radio
value=A>A.40．15．1．0／17<BR> <INPUT class=radio
name=text1578 onblur="this.className='radio'"
onfocus="this.className='inputedit';this.select()" type=radio
value=B>B.40．15．2．0／17<BR> <INPUT class=radio
name=text1578 onblur="this.className='radio'"
onfocus="this.className='inputedit';this.select()" type=radio
value=C>C.40．15．100．0／17<BR> <INPUT class=radio
name=text1578 onblur="this.className='radio'"
onfocus="this.className='inputedit';this.select()" type=radio
value=D>D.40．15．128．0／17<BR></TD></TR>
<TR class=trh1>
<TD align=middle height=212 width=29>20 </TD>
<TD align=left height=212 width=607> Linux中一种常用的引导工具是 (51) ©)
<BR>答： <INPUT class=radio name=text1586
onblur="this.className='radio'"
onfocus="this.className='inputedit';this.select()" type=radio
value=A>A.reboot<BR> <INPUT class=radio name=text1586
onblur="this.className='radio'"
onfocus="this.className='inputedit';this.select()" type=radio
value=B>B.1ilo<BR> <INPUT class=radio name=text1586
onblur="this.className='radio'"
onfocus="this.className='inputedit';this.select()" type=radio
value=C>C.gone<BR> <INPUT class=radio name=text1586
onblur="this.className='radio'"
onfocus="this.className='inputedit';this.select()" type=radio
value=D>D.restart<BR></TD></TR>
<TR class=trh1>
<TD align=middle height=212 width=29>21 </TD>
<TD align=left height=212 width=607>
为一块设备名为eth0的网卡分配p地址和子网掩码的命令是： (53) ©) <BR>答： <INPUT class=radio
name=text1590 onblur="this.className='radio'"
onfocus="this.className='inputedit';this.select()" type=radio
value=A>A.serserialeth0202．112．58．200netmask255．255．255．0<BR>
<INPUT class=radio name=text1590 onblur="this.className='radio'"
onfocus="this.className='inputedit';this.select()" type=radio
value=B>B.ifconfigeth0202．112．58．200netmask255．255．255．0<BR>
<INPUT class=radio name=text1590 onblur="this.className='radio'"
onfocus="this.className='inputedit';this.select()" type=radio
value=C>C.minicometh0202．112．58．200netmask255．255．255．0<BR>
<INPUT class=radio name=text1590 onblur="this.className='radio'"
onfocus="this.className='inputedit';this.select()" type=radio
value=D>D.mounteth0202．112．58．200netmask255．255．255．0<BR></TD></TR>
<TR class=trh1>
<TD align=middle height=212 width=29>22 </TD>
<TD align=left height=212 width=607>
在自治系统内部的各个路由器之间，运行的是内部网关协议IGP。它执行 (57) 。©) <BR>答： <INPUT class=radio
name=text1594 onblur="this.className='radio'"
onfocus="this.className='inputedit';this.select()" type=radio
value=A>A.路由选择算法<BR> <INPUT class=radio name=text1594
onblur="this.className='radio'"
onfocus="this.className='inputedit';this.select()" type=radio
value=B>B.距离矢量算法<BR> <INPUT class=radio name=text1594
onblur="this.className='radio'"
onfocus="this.className='inputedit';this.select()" type=radio
value=C>C.链路状态算法<BR> <INPUT class=radio name=text1594
onblur="this.className='radio'"
onfocus="this.className='inputedit';this.select()" type=radio
value=D>D.内部网关算法<BR></TD></TR>
<TR class=trh1>
<TD align=middle height=212 width=29>23 </TD>
<TD align=left height=212 width=607>
在自治系统内部的各个路由器之间，运行的是内部网关协议IGP。当网络规模扩大时，该算法传送的路由信息太多，增加了网络负载，后来又出现了执行最短路径优先算法的IGP。当路由信息改变后，路由器按照
(59) 算法更新路由表。©) <BR>答： <INPUT class=radio name=text1598
onblur="this.className='radio'"
onfocus="this.className='inputedit';this.select()" type=radio
value=A>A.Diikstra<BR> <INPUT class=radio
name=text1598 onblur="this.className='radio'"
onfocus="this.className='inputedit';this.select()" type=radio
value=B>B.Ford-Fulkerson<BR> <INPUT class=radio
name=text1598 onblur="this.className='radio'"
onfocus="this.className='inputedit';this.select()" type=radio
value=C>C.Floyd<BR> <INPUT class=radio name=text1598
onblur="this.className='radio'"
onfocus="this.className='inputedit';this.select()" type=radio
value=D>D.WarshaH<BR></TD></TR>
<TR class=trh1>
<TD align=middle height=212 width=29>24 </TD>
<TD align=left height=212 width=607> 帧中继网的虚电路建立在 (61) ©)
<BR>答： <INPUT class=radio name=text1600
onblur="this.className='radio'"
onfocus="this.className='inputedit';this.select()" type=radio
value=A>A.数据链路层<BR> <INPUT class=radio name=text1600
onblur="this.className='radio'"
onfocus="this.className='inputedit';this.select()" type=radio
value=B>B.网络层<BR> <INPUT class=radio name=text1600
onblur="this.className='radio'"
onfocus="this.className='inputedit';this.select()" type=radio
value=C>C.传输层<BR> <INPUT class=radio name=text1600
onblur="this.className='radio'"
onfocus="this.className='inputedit';this.select()" type=radio
value=D>D.会话层<BR></TD></TR>
<TR class=trh1>
<TD align=middle height=212 width=29>25 </TD>
<TD align=left height=212 width=607> 设有某一个令牌环网长度为 400 米，环上有
28 个站点，其数据传输率为 4MbpS，环上信号的传播速度为 200 米/μS，每个站点具有 1bit
时延，当始终有一半站点打开工作时，要保证环网的正常运行，至少还要将电缆的长度增加__(5)__米。©) <BR>答： <INPUT
class=radio name=text1649 onblur="this.className='radio'"
onfocus="this.className='inputedit';this.select()" type=radio
value=A>A.50<BR> <INPUT class=radio name=text1649
onblur="this.className='radio'"
onfocus="this.className='inputedit';this.select()" type=radio
value=B>B.100<BR> <INPUT class=radio name=text1649
onblur="this.className='radio'"
onfocus="this.className='inputedit';this.select()" type=radio
value=C>C.200<BR> <INPUT class=radio name=text1649
onblur="this.className='radio'"
onfocus="this.className='inputedit';this.select()" type=radio
value=D>D.400<BR></TD></TR>
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<TD align=middle height=212 width=29>26 </TD>
<TD align=left height=212 width=607> 在一个带宽为
3KHZ、没有噪声的信道，传输二进制信号时能够达到的极限数据传输率为__(6)__。©) <BR>答： <INPUT
class=radio name=text1651 onblur="this.className='radio'"
onfocus="this.className='inputedit';this.select()" type=radio
value=A>A.3Kbps<BR> <INPUT class=radio name=text1651
onblur="this.className='radio'"
onfocus="this.className='inputedit';this.select()" type=radio
value=B>B.6Kbps<BR> <INPUT class=radio name=text1651
onblur="this.className='radio'"
onfocus="this.className='inputedit';this.select()" type=radio
value=C>C.56Kbps<BR> <INPUT class=radio name=text1651
onblur="this.className='radio'"
onfocus="this.className='inputedit';this.select()" type=radio
value=D>D.10Mbps<BR></TD></TR>
<TR class=trh1>
<TD align=middle height=212 width=29>27 </TD>
<TD align=left height=212 width=607> 一个带宽为 3KHZ、信噪比为 30dB
的信道，能够达到的极限数据传输率为__(7)__。©) <BR>答： <INPUT class=radio name=text1653
onblur="this.className='radio'"
onfocus="this.className='inputedit';this.select()" type=radio
value=A>A.12Kbps<BR> <INPUT class=radio name=text1653
onblur="this.className='radio'"
onfocus="this.className='inputedit';this.select()" type=radio
value=B>B.30Kbps<BR> <INPUT class=radio name=text1653
onblur="this.className='radio'"
onfocus="this.className='inputedit';this.select()" type=radio
value=C>C.56Kbps<BR> <INPUT class=radio name=text1653
onblur="this.className='radio'"
onfocus="this.className='inputedit';this.select()" type=radio
value=D>D.10Mbps<BR></TD></TR>
<TR class=trh1>
<TD align=middle height=212 width=29>28 </TD>
<TD align=left height=212 width=607>
在一个无限带宽的无噪声信道上，传输二进制信号，当信号的带宽为 3KHz 时，能达到的极限数据传输率为__(10)__Kbps 。©) <BR>答：
<INPUT class=radio name=text1659 onblur="this.className='radio'"
onfocus="this.className='inputedit';this.select()" type=radio
value=A>A.1.5<BR> <INPUT class=radio name=text1659
onblur="this.className='radio'"
onfocus="this.className='inputedit';this.select()" type=radio
value=B>B.3<BR> <INPUT class=radio name=text1659
onblur="this.className='radio'"
onfocus="this.className='inputedit';this.select()" type=radio
value=C>C.6<BR> <INPUT class=radio name=text1659
onblur="this.className='radio'"
onfocus="this.className='inputedit';this.select()" type=radio value=D>D.3
log23<BR></TD></TR>
<TR class=trh1>
<TD align=middle height=212 width=29>29 </TD>
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