{"msg":"第三节 数据通信与计算机网络","code":200,"data":{"currentIndex":null,"examId":null,"examTime":null,"questionList":[{"id":"796237635201814529","title":"一家连锁店需要设计一种编址方案来支持全国各个店面销售网络，店面有300家左右，每个店面一个子网，每个子网中的终端最多50台，该连锁店从ISP处得到一个B 类地址，应该采用的子网掩码是（65）。","analyze":"每个子网有50台终端，至少要占用6位地址码。300家门店需要占用9位地址码。 对于B类网络，用第三字节的8位和第四字节的1位来区分不同的门店子网，用第四字节的7位作为子网内的主机地址，是一种合适的编址方案。","multi":0,"questionType":1,"answer":"A","chooseItem":["796237636258779137"],"itemList":[{"id":"796237636258779137","questionId":"796237635201814529","content":" 255.255.255.128","answer":1,"chooseValue":"A"},{"id":"796237636267167745","questionId":"796237635201814529","content":" 255.255.252.0","answer":0,"chooseValue":"B"},{"id":"796237636283944961","questionId":"796237635201814529","content":" 255.255.248.0","answer":0,"chooseValue":"C"},{"id":"796237636296527873","questionId":"796237635201814529","content":" 255.255.255.224","answer":0,"chooseValue":"D"}],"userAnswer":null,"userChooseItem":null,"answerCorrect":null,"userCollect":null},{"id":"796237777757818881","title":"网络拓扑设计是计算机网络建设的第一步。它对网络的影响主要表现在（67）。①网络性能②系统可靠性③出口带宽④网络协议","analyze":"本试题考查网络规划与设计，以及网络拓扑结构等知识。<br>网络拓扑结构不同，对网络的性能、系统可靠性、网络协议的选择均会造成影响； 出口带宽与ISP提供的容量有关，与内部网络结构的设计无关。","multi":0,"questionType":1,"answer":"D","chooseItem":["796237778697342977"],"itemList":[{"id":"796237778651205633","questionId":"796237777757818881","content":" ①、②","answer":0,"chooseValue":"A"},{"id":"796237778663788545","questionId":"796237777757818881","content":" ①、②、③","answer":0,"chooseValue":"B"},{"id":"796237778684760065","questionId":"796237777757818881","content":" ③、④","answer":0,"chooseValue":"C"},{"id":"796237778697342977","questionId":"796237777757818881","content":" 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利用率是描述服务性能的指标","answer":1,"chooseValue":"D"}],"userAnswer":null,"userChooseItem":null,"answerCorrect":null,"userCollect":null},{"id":"796237786549080065","title":"网络管理系统中故障管理的目标是（）。","analyze":"本题考査网络管理系统方面的基础知识。<br>ISO/IEC7498-4文档定义了网络管理的相关知识，其中故障管理的目标应包括：故障监测、故障报警、故障信息管理、排错支持工具、检索/分析故障信息等内容。","multi":0,"questionType":1,"answer":"D","chooseItem":["796237787538935809"],"itemList":[{"id":"796237787484409857","questionId":"796237786549080065","content":" 自动排除故障","answer":0,"chooseValue":"A"},{"id":"796237787505381377","questionId":"796237786549080065","content":" 优化网络性能","answer":0,"chooseValue":"B"},{"id":"796237787522158593","questionId":"796237786549080065","content":" 提升网络安全","answer":0,"chooseValue":"C"},{"id":"796237787538935809","questionId":"796237786549080065","content":" 自动监测故障","answer":1,"chooseValue":"D"}],"userAnswer":null,"userChooseItem":null,"answerCorrect":null,"userCollect":null},{"id":"796237726973186049","title":"在网络设计阶段进行通信流量分析时可以采用简单的80/20规则，以下关于这种规则的叙述中，正确的是（69）。","analyze":"在网络规划过程中，需要根据业务需求和应用需求来计算各个信息流量的大小，并根据通信模式、通信边界的分析，确定不同信息流在网络的不同区域和区域边界上的分布情况。<br>对于较为简单的网络，不需要进行复杂的通信流量分析，仅采用一些简单的方法就可以确定通信流量，例如80/20规则等。但是对于复杂的网络，仍必须进行复杂的通信流量分布分析。<br>80/20规则是一种设计思路，通过这种方式可以限制用户的不合理需求，是最优化地使用网络骨干和使用昂贵的广域网连接的一种行之有效的方法。例如，如果核心交换机容量为100Mb/s，局域网至外部的带宽应限制在20Mb/s以内。80/20规则适用于内部交流较多、外部访问相对较少、网络较为简单、不存在特殊应用的网络或网段。<br>随着互联网络的发展，出现了另外一种通信情况，即网段内部用户之间相互访问较少，大多数通信都是对网段外部资源的访问。例如小区内计算机用户形成的局域网络，大型公司用于实现远程协同工作的工作组网络等。对于这种情况，可以采用20/80规则。20/80规则根据用户和应用需求的统计数据产生网段内的通信总量大小，并认为总量的20%是在网段内部的流量，而80%是网段外部的流量。","multi":0,"questionType":1,"answer":"C","chooseItem":["796237727929487361"],"itemList":[{"id":"796237727900127233","questionId":"796237726973186049","content":" 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这个规则适用的网络允许存在具有特殊应用的网段","answer":0,"chooseValue":"D"}],"userAnswer":null,"userChooseItem":null,"answerCorrect":null,"userCollect":null},{"id":"796237809080881153","title":"设计骨干网时，应该在性能和成本之间寻找平衡。以下叙述中，（67）是正确的。","analyze":"主干网一般用来连接建筑群和服务器群，是网络的大动脉。主干网技术的选择，要根据需求分析中的地理距离、信息流量和数据负载的轻重而定。连接建筑群的主干网一般以光缆作传输介质。<br>FDDI基本属于过时技术，目前较少应用；ATM是面向连接的网络，实时传输效率高，但其在局域网的应用需要ELAN仿真来实现，效率低，不适宜用作局域网或园区网。千兆以太网一般采用光缆作传输介质，多种波长的单模和多模光纤分别用于不同的场合和距离，由于建筑群布线线路路径复杂的特殊性，一般直线距离超过300米的建筑物之间的千兆以太网线路就必须要用单模光纤。如经费难以支持千兆以太网，可以采用100Base-FX,即用光纤建立快速以太网，其端口价格低，对光缆的要求也不高。","multi":0,"questionType":1,"answer":"C","chooseItem":["796237809999433729"],"itemList":[{"id":"796237809970073601","questionId":"796237809080881153","content":" ATM在局域网的所有应用可用ELAN来实现，带宽效率高，实时性好，适宜用作园区网","answer":0,"chooseValue":"A"},{"id":"796237809982656513","questionId":"796237809080881153","content":" 双星树结构的主干网，虽然不能均衡负载，成本也较高，但具有更高的可用性","answer":0,"chooseValue":"B"},{"id":"796237809999433729","questionId":"796237809080881153","content":" 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66Mb/s","answer":0,"chooseValue":"C"},{"id":"796237687928410113","questionId":"796237687014051841","content":" 528Mb/s","answer":0,"chooseValue":"D"}],"userAnswer":null,"userChooseItem":null,"answerCorrect":null,"userCollect":null},{"id":"796237730047610881","title":"如果发现网络的数据传输很慢，服务质量也达不到要求，应该首先检查（）的工作情况。","analyze":"如果网络的数据传输很慢，服务质量也达不到要求，通常先要检查网络层工作是否正常。","multi":0,"questionType":1,"answer":"C","chooseItem":["796237731008106497"],"itemList":[{"id":"796237730978746369","questionId":"796237730047610881","content":" 物理层","answer":0,"chooseValue":"A"},{"id":"796237730991329281","questionId":"796237730047610881","content":" 会话层","answer":0,"chooseValue":"B"},{"id":"796237731008106497","questionId":"796237730047610881","content":" 网络层","answer":1,"chooseValue":"C"},{"id":"796237731020689409","questionId":"796237730047610881","content":" 传输层","answer":0,"chooseValue":"D"}],"userAnswer":null,"userChooseItem":null,"answerCorrect":null,"userCollect":null},{"id":"796237597390163969","title":"<p><strong>请作答第<span style=\"color: red\">2</span>个空。</strong></p>ICMP协议属于英特网中的（65）协议，ICMP协议数据单元封装在（66）中传送。","analyze":"ICMP (Internet control Message Protocol)与IP协议同属于网络层，用于传送有关通信问题的消息，例如数据报不能到达目标站，路由器没有足够的缓存空间，或者路由器向发送主机提供最短通路信息等。ICMP报文封装在IP数据报中传送，因而不保证可靠的提交。ICMP报文有11种之多，报文格式如下图所示。其中的类型字段表示ICMP报文的类型，代码字段可表示报文的少量参数，当参数较多时写入32位的参数字段，ICMP报文携带的信息包含在可变长的信息字段中，校验和字段是关于整个ICMP报文的校验和。","multi":0,"questionType":1,"answer":"D","chooseItem":["796237598350659585"],"itemList":[{"id":"796237598304522241","questionId":"796237597390163969","content":" 以太帧","answer":0,"chooseValue":"A"},{"id":"796237598321299457","questionId":"796237597390163969","content":" TCP段","answer":0,"chooseValue":"B"},{"id":"796237598338076673","questionId":"796237597390163969","content":" UDP数据报","answer":0,"chooseValue":"C"},{"id":"796237598350659585","questionId":"796237597390163969","content":" IP数据报","answer":1,"chooseValue":"D"}],"userAnswer":null,"userChooseItem":null,"answerCorrect":null,"userCollect":null},{"id":"796237606265311233","title":"IPv6地址分为3种类型，它们是（67）。","analyze":"IPv6地址是一个或一组接口的标识符。IPv6地址被分配到接口，而不是分配给结点。IPv6地址有三种类型：<br>①单播（Unicast)地址。<br>单播地址是单个网络接口的标识符。对于有多个接口的结点，其中任何一个单播地址都可以用作该结点的标识符。但是为了满足负载平衡的需要，在RFC 2373中规定，只要在实现中多个接口看起来形同一个接口就允许这些接口使用同一地址。IPv6的单播地址是用一定长度的格式前缀汇聚的地址，类似于IPv4中的CIDR地址。单播地址中有下列两种特殊地址：<br>•不确定地址：地址0:0:0:0:0:0:0:0称为不确定地址，不能分配给任何结点。<br>•回环地址：地址0:0:0:0:0:0:0:1称为回环地址，结点用这种地址向自身发送IPv6分组。这种地址不能分配给任何物理接口。<br>②任意播（AnyCast)地址。<br>这种地址表示一组接口（可属于不同结点）的标识符。发往任意播地址的分组被送给该地址标识的接口之一，通常是路由距离最近的接口。对IPv6任意播地址存在下列限制:<br>•任意播地址不能用作源地址，而只能作为目标地址；<br>•任意播地址不能指定给IPv6主机，只能指定给IPv6路由器。<br>③组播（Multicast)地址。<br>组播地址是一组接口（一般属于不同结点）的标识符，发往组播地址的分组被传送给该地址标识的所有接口。IPv6中没有广播地址，它的功能已被组播地址所代替。<br>在IPv6地址中，任何全“0”和全“1”字段都是合法的，除非特别排除的之外。特别是前缀可以包含“0”值字段，也可以用“0”作为终结字段。一个接口可以被赋予任何类型的多个地址（单播、任意播、组播）或地址范围。","multi":0,"questionType":1,"answer":"B","chooseItem":["796237607167086593"],"itemList":[{"id":"796237607150309377","questionId":"796237606265311233","content":" A类地址、B类地址、C类地址","answer":0,"chooseValue":"A"},{"id":"796237607167086593","questionId":"796237606265311233","content":" 单播地址、组播地址、任意播地址","answer":1,"chooseValue":"B"},{"id":"796237607179669505","questionId":"796237606265311233","content":" 单播地址、组播地址、广播地址","answer":0,"chooseValue":"C"},{"id":"796237607192252417","questionId":"796237606265311233","content":" 公共地址、站点地址、接口地址","answer":0,"chooseValue":"D"}],"userAnswer":null,"userChooseItem":null,"answerCorrect":null,"userCollect":null},{"id":"796237748167004161","title":"所列出的4个IPv6地址中，无效的地址是（）。","analyze":"4个IPv6地址中，无效的地址是B.2001:3452:4955:2367::，最后一对冒号的写法是错误的。其他3种写法都正确，：：192:168:0:1是一个IPv4地址，2002:c0a8:101::43中的双冒号表示4个双字节，2003:dead:beef:4dad:2，3:34:bb:101是完整的IPv6地址。","multi":0,"questionType":1,"answer":"B","chooseItem":["796237749072973825"],"itemList":[{"id":"796237749052002305","questionId":"796237748167004161","content":" ::192:168:0:1","answer":0,"chooseValue":"A"},{"id":"796237749072973825","questionId":"796237748167004161","content":" :2001:3452:4955:2367::","answer":1,"chooseValue":"B"},{"id":"796237749089751041","questionId":"796237748167004161","content":" 2002:c0a8:101::43","answer":0,"chooseValue":"C"},{"id":"796237749114916865","questionId":"796237748167004161","content":" 2003:dead:beef:4dad:23:34:bb:101","answer":0,"chooseValue":"D"}],"userAnswer":null,"userChooseItem":null,"answerCorrect":null,"userCollect":null},{"id":"796237765967630337","title":"根据用户需求选择正确的网络技术是保证网络建设成功的关键，在选择网络技术时应考虑多种因素。以下叙述中，不正确的是（70）。","analyze":"根据用户需求选择网络技术时应考虑如下因素：<br>①通信带宽。所选择的网络技术必须保证足够的带宽，能够保证用户快速地访问应用系统。在进行选择时，不仅局限于现有的应用需求，还要适当考虑将来的带宽增长需求。<br>②技术成熟性。所选择的网络技术必须是成熟稳定的技术，有些新的网络技术在尚没有大规模投入使用时，还存在着较多不确定因素，这将会给网络建设带来很多无法估量的损失。对于大型网络工程来说，项目本身不能成为新技术的试验田。使用较为成熟、拥有较多案例的技术是明智的选择。<br>③可扩充性。网络设计的设计依据是详细的需求分析，但是在选择网络技术时，不能仅考虑当前的需求而忽视未来的发展。在大多数情况下，设计人员都会在网络带宽、数据吞吐量、用户并发数等方面设计中预留一定的冗余量。一般来说，这个冗余量值在70%~80%之间。<br>④高投资产出。选择网络技术的关键是投入产出比，尤其是一些借助于网络来实现营运的工程项目，只有通过投入产出分析，才能最后决定使用何种技术。","multi":0,"questionType":1,"answer":"C","chooseItem":["796237766923931649"],"itemList":[{"id":"796237766873600001","questionId":"796237765967630337","content":" 选择的网络技术必须保证足够的带宽，使得用户能够快速地访问应用系统","answer":0,"chooseValue":"A"},{"id":"796237766902960129","questionId":"796237765967630337","content":" 选择网络技术时不仅要考虑当前的需求，而且要考虑未来的发展","answer":0,"chooseValue":"B"},{"id":"796237766923931649","questionId":"796237765967630337","content":" 对于大型网络工程，应该选择具有前_性的新的网络技术","answer":1,"chooseValue":"C"},{"id":"796237766940708865","questionId":"796237765967630337","content":" 选择网络技术要考虑投入产出比，通过投入产出分析确定使用何种技术","answer":0,"chooseValue":"D"}],"userAnswer":null,"userChooseItem":null,"answerCorrect":null,"userCollect":null},{"id":"796237594236047361","title":"<p><strong>请作答第<span style=\"color: red\">1</span>个空。</strong></p>ICMP协议属于英特网中的（65）协议，ICMP协议数据单元封装在（66）中传送。","analyze":"ICMP (Internet control Message Protocol)与IP协议同属于网络层，用于传送有关通信问题的消息，例如数据报不能到达目标站，路由器没有足够的缓存空间，或者路由器向发送主机提供最短通路信息等。ICMP报文封装在IP数据报中传送，因而不保证可靠的提交。ICMP报文有11种之多，报文格式如下图所示。其中的类型字段表示ICMP报文的类型，代码字段可表示报文的少量参数，当参数较多时写入32位的参数字段，ICMP报文携带的信息包含在可变长的信息字段中，校验和字段是关于整个ICMP报文的校验和。<br><img alt=\"\" width=\"355\" height=\"72\" src=\"https://image.chaiding.com/ruankao/b0b968a9ce2ca8d9582c7a810966ed42.jpg?x-oss-process=style/ruankaodaren\">","multi":0,"questionType":1,"answer":"B","chooseItem":["796237595196542977"],"itemList":[{"id":"796237595179765761","questionId":"796237594236047361","content":" 数据链路层","answer":0,"chooseValue":"A"},{"id":"796237595196542977","questionId":"796237594236047361","content":" 网络层","answer":1,"chooseValue":"B"},{"id":"796237595209125889","questionId":"796237594236047361","content":" 传输层","answer":0,"chooseValue":"C"},{"id":"796237595225903105","questionId":"796237594236047361","content":" 会话层","answer":0,"chooseValue":"D"}],"userAnswer":null,"userChooseItem":null,"answerCorrect":null,"userCollect":null},{"id":"796237675974643713","title":"使用netstat-o命令可（）。","analyze":"本题考查网络管理命令netstat的使用及相关参数的作用。<br>Netstat命令用于显示TCP连接。Netstat命令的语法如下：<br>netstat[-a][-e][-n][-o][-pProtocol][-r][-s][Interval]<br>对以上参数解释如下。<br>•-a：显示所有活动的TCP连接，以及正在监听的TCP和UDP端口。<br>•-e：显示以太网统计信息，例如发送和接收的字节数，以及出错的次数等。这个参数可以与-s参数联合使用。<br>•-n：显示活动的TCP连接，地址和端口号以数字形式表示。<br>•-o：显示活动的TCP连接以及每个连接对应的进程IIX在Windows任务管理器中可以找到与进程ID对应的应用。这个参数可以与-a、-n和-p联合使用。<br>•-p：Protoco/用标识符Protocol指定要显示的协议，可以是TCP、UDP、TCPv6或者UDPv6。如果与参数-s联合使用，则可以显示协议TCP、UDP、ICMP、IP、TCPv6、UDPv6、ICMPv6或IPv6的统计数据。u2003<br>•-s：显示每个协议的统计数据。默认情况下，统计TCP、UDP、ICMP和IP协议发送和接收的数据包、出错的数据包、连接成功或失败的次数等。如果与-p参数联合使用，可以指定要显示统计数据的协议。<br>•-r：显示IP路由表的内容，其作用等价于路由打印命令routeprint。<br>•Interval：说明重新显示信息的时间间隔，键入Ctrl+C则停止显示。如果不使用这个参数，则只显示一次。","multi":0,"questionType":1,"answer":"D","chooseItem":["796237677123883009"],"itemList":[{"id":"796237677060968449","questionId":"796237675974643713","content":" 显示所测试网络的IP、ICMP、TCP、UDP协议的统计信息","answer":0,"chooseValue":"A"},{"id":"796237677081939969","questionId":"796237675974643713","content":" 显示以太网统计信息","answer":0,"chooseValue":"B"},{"id":"796237677098717185","questionId":"796237675974643713","content":" 以数字格式显示所有连接、地址及端口","answer":0,"chooseValue":"C"},{"id":"796237677123883009","questionId":"796237675974643713","content":" 显示每个连接的进程ID","answer":1,"chooseValue":"D"}],"userAnswer":null,"userChooseItem":null,"answerCorrect":null,"userCollect":null},{"id":"796237689899732993","title":"假设需要把25盒磁带数据（每盒磁带数据量40GB)从甲地传输到乙地，甲、乙相距1km，可以采用的方法有汽车运输和TCP/IP网络传输，网络传输介质可选用双绞线、单模光纤、多模光纤等。通常情况下，采用（12）介质，所用时间最短。","analyze":"&nbsp;&nbsp;&nbsp; 为了便于讨论，可以简单估算每种介质的传输时间。一般情况下，汽车的速度为30km/h，可合理假设装车和卸货时间分别是5分钟；双绞线的传输速率为100Mb/s，多模光纤的传输速率为1000Mb/s，单模光纤的传输速率为2500Mb/s，并假设有足够的磁带机系统而忽略磁带数据上网所需时间。<br>&nbsp;&nbsp;&nbsp; 每种介质的传输时间为：<br><img alt=\"\" width=\"500\" height=\"150\" src=\"https://image.chaiding.com/ruankao/68fa493142c3f4b9144e92cfddd6a01d.jpg?x-oss-process=style/ruankaodaren\"><br>&nbsp;&nbsp;&nbsp; 因此采用汽车所用时间最短，一辆装载磁带的汽车等同于一个高带宽介质。","multi":0,"questionType":1,"answer":"A","chooseItem":["796237690885394433"],"itemList":[{"id":"796237690885394433","questionId":"796237689899732993","content":" 汽车","answer":1,"chooseValue":"A"},{"id":"796237690902171649","questionId":"796237689899732993","content":" 双绞线","answer":0,"chooseValue":"B"},{"id":"796237690910560257","questionId":"796237689899732993","content":" 多模光纤","answer":0,"chooseValue":"C"},{"id":"796237690923143169","questionId":"796237689899732993","content":" 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72.5ms","answer":1,"chooseValue":"D"}],"userAnswer":null,"userChooseItem":null,"answerCorrect":null,"userCollect":null},{"id":"796237732983623681","title":"如果在网络的入口处通过设置ACL封锁了TCP和UDP端口21、23和25，则能够访问该网络的应用是（）。","analyze":"由于TCP和UDP端口21、23和25被封锁，它们分别是FTP、Telnet和SMTP的端口号，所以只有DNS应用可以访问该网络。","multi":0,"questionType":1,"answer":"B","chooseItem":["796237733893787649"],"itemList":[{"id":"796237733881204737","questionId":"796237732983623681","content":" FTP","answer":0,"chooseValue":"A"},{"id":"796237733893787649","questionId":"796237732983623681","content":" DNS","answer":1,"chooseValue":"B"},{"id":"796237733906370561","questionId":"796237732983623681","content":" SMTP","answer":0,"chooseValue":"C"},{"id":"796237733918953473","questionId":"796237732983623681","content":" Telnet","answer":0,"chooseValue":"D"}],"userAnswer":null,"userChooseItem":null,"answerCorrect":null,"userCollect":null},{"id":"796237600431034369","title":"IEEE 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依据逻辑网络设计的要求，确定设备的具体物理分布和运行环境","answer":1,"chooseValue":"B"},{"id":"796237790416228353","questionId":"796237789493481473","content":" 根据需求规范和通信规范，实施资源分配和安全规划","answer":0,"chooseValue":"C"},{"id":"796237790433005569","questionId":"796237789493481473","content":" 理解网络应该具有的功能和性能，最终设计出符合用户需求的网络","answer":0,"chooseValue":"D"}],"userAnswer":null,"userChooseItem":null,"answerCorrect":null,"userCollect":null},{"id":"796237609121632257","title":"IPv6站点通过IPv4网络通信需要使用隧道技术，常用的3种自动隧道技术是（）。","analyze":"IPv6站点通过IPv4网络通信，最常用的3种自动隧道技术是6to.4隧道、6over4隧道和ISATAP隧道。","multi":0,"questionType":1,"answer":"B","chooseItem":["796237610019213313"],"itemList":[{"id":"796237610006630401","questionId":"796237609121632257","content":" VPN隧道、PPTP隧道和IPsec隧道","answer":0,"chooseValue":"A"},{"id":"796237610019213313","questionId":"796237609121632257","content":" 6to4隧道、6over4隧道和ISATAP隧道","answer":1,"chooseValue":"B"},{"id":"796237610027601921","questionId":"796237609121632257","content":" VPN隧道、PPP隧道和ISATAP隧道","answer":0,"chooseValue":"C"},{"id":"796237610040184833","questionId":"796237609121632257","content":" IPsec隧道、6over4隧道和PPTP隧道","answer":0,"chooseValue":"D"}],"userAnswer":null,"userChooseItem":null,"answerCorrect":null,"userCollect":null},{"id":"796237716663586817","title":"在异步通信中，每个字符包含1位起始位、7位数据位、1位奇偶位和2位终止位，每秒钟传送100个字符，则有效数据速率为（68）。","analyze":"异步通信方案是把字符作为同步的单位，字符之间插入少量的同步信息。面向字符的同步协议依赖于具体的字符编码，不同字符编码的系统之间不能通信。按照本题意说明，每秒传送100个字符，每个字符中的有效信息占7/11，所以有效数据速率为11*100*7/11=700b/s。","multi":0,"questionType":1,"answer":"B","chooseItem":["796237717582139393"],"itemList":[{"id":"796237717565362177","questionId":"796237716663586817","content":" 100b/s","answer":0,"chooseValue":"A"},{"id":"796237717582139393","questionId":"796237716663586817","content":" 700b/s","answer":1,"chooseValue":"B"},{"id":"796237717598916609","questionId":"796237716663586817","content":" 800b/s","answer":0,"chooseValue":"C"},{"id":"796237717611499521","questionId":"796237716663586817","content":" 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0.999","answer":0,"chooseValue":"C"},{"id":"796237697009078273","questionId":"796237696027611137","content":" 0.9996","answer":0,"chooseValue":"D"}],"userAnswer":null,"userChooseItem":null,"answerCorrect":null,"userCollect":null},{"id":"796237627492683777","title":"TCP协议在建立连接的过程中可能处于不同的状态，用netstat命令显示出TCP连接的状态为SYN_SEND，则这个连接正处于（69）。","analyze":"<img alt=\"\" width=\"392\" height=\"456\" src=\"https://image.chaiding.com/ruankao/6738993e1b6b1b155b3f713480992439.jpg?x-oss-process=style/ruankaodaren\"><br>上图表示TCP的连接状态。事实上，在TCP协议运行过程中，有多个连接处于不同的状态。当TCP处于SYN_SEND状态时，表示协议实体已主动发出连接建立请求。","multi":0,"questionType":1,"answer":"B","chooseItem":["796237628440596481"],"itemList":[{"id":"796237628428013569","questionId":"796237627492683777","content":" 等待对方的建立连接请求","answer":0,"chooseValue":"A"},{"id":"796237628440596481","questionId":"796237627492683777","content":" 已主动发出连接建立请求","answer":1,"chooseValue":"B"},{"id":"796237628461568001","questionId":"796237627492683777","content":" 等待对方的连接释放请求","answer":0,"chooseValue":"C"},{"id":"796237628478345217","questionId":"796237627492683777","content":" 收到对方的连接建立请求","answer":0,"chooseValue":"D"}],"userAnswer":null,"userChooseItem":null,"answerCorrect":null,"userCollect":null},{"id":"796237760888328193","title":"某局域网访问Internet速度很慢，网管员测试发现是局域网内有大量的广播包，（70）不可能有效地解决该网络问题。","analyze":"如果出现ARP病毒或蠕虫病毒，它们会向局域网其他终端发送大量广播包进行繁殖；如果网卡有故障，其他主机会不停发送广播包找该主机；如果局域网内有环路出现，广播包不断转发；提高出口带宽速度不能解决大量广播包问题。","multi":0,"questionType":1,"answer":"D","chooseItem":["796237761840435201"],"itemList":[{"id":"796237761802686465","questionId":"796237760888328193","content":" 在局域网内査杀可能存在的ARP病毒和蠕虫病毒","answer":0,"chooseValue":"A"},{"id":"796237761811075073","questionId":"796237760888328193","content":" 检査局域网内交换机端口、主机上的网卡是否有故障","answer":0,"chooseValue":"B"},{"id":"796237761823657985","questionId":"796237760888328193","content":" 检查局域网内是否有环路出现","answer":0,"chooseValue":"C"},{"id":"796237761840435201","questionId":"796237760888328193","content":" 提高出口带宽速度","answer":1,"chooseValue":"D"}],"userAnswer":null,"userChooseItem":null,"answerCorrect":null,"userCollect":null},{"id":"796237683998347265","title":"假设生产管理网络系统采用B/S工作方式，经常上网的用户数为200,每个用户平均每分钟产生8个事务处理，每个事务处理的规模平均为0.05MB,则这个系统需要的信息传输速率为（67）。","analyze":"根据下面的公式可以计算出应用需要的传输信息速率：<br>总信息传输速率=平均事务量大小×每字节位数×每个会话事务数×平均用户数/平均会话时长<br>根据这个公式，结算结果为：0.05×8×8×200/60=10.7 (Mb/s)","multi":0,"questionType":1,"answer":"C","chooseItem":["796237685084672001"],"itemList":[{"id":"796237685055311873","questionId":"796237683998347265","content":" 4.3Mb/s","answer":0,"chooseValue":"A"},{"id":"796237685072089089","questionId":"796237683998347265","content":" 7.8Mb/s","answer":0,"chooseValue":"B"},{"id":"796237685084672001","questionId":"796237683998347265","content":" 10.7Mb/s","answer":1,"chooseValue":"C"},{"id":"796237685101449217","questionId":"796237683998347265","content":" 17.8Mb/s","answer":0,"chooseValue":"D"}],"userAnswer":null,"userChooseItem":null,"answerCorrect":null,"userCollect":null},{"id":"796237658245320705","title":"主机hostl对host2进行域名查询的过程如下图所示，下列说法中正确的是（64）。<br><img alt=\"\" width=\"285\" height=\"234\" src=\"https://image.chaiding.com/ruankao/9a4651deacc0b58e6a2ed3a599d1ae97.jpg?x-oss-process=style/ruankaodaren\">","analyze":"本试题考查域名服务器进行域名解析时的查询方法。<br>DNS客户端都配置了一个或多个DNS服务器的地址，无论是静态或动态配置的，这些DNS服务器都是用户所在域的授权服务器，而用户主机则是该域的成员。当用户在浏览器地址栏输入一个域名时，客户端就可以向本地的DNS服务器发出查询请求。查询过程分为两种查询方式：<br>①递归查询：当用户发出查询请求时，本地服务器要进行递归查询。这种查询方式要求服务器彻底地进行名字解析，并返回最后的结果——IP地址或错误信息。如果查询请求在本地服务器中不能完成，那么服务器就根据它的配置向域名树中的上级服务器进行查询，在最坏的情况下可能要查询到根服务器。每次查询返回的结果如果是其他名字服务器的IP地址，则本地服务器要把查询请求发送给这些服务器做进一步的查询。<br>②迭代查询：服务器与服务器之间的查询采用迭代的方式进行，发出查询请求的服务器得到的响应可能不是目标的IP地址，而是其他服务器的引用（名字和地址)，那么本地服务器就要访问被引用的服务器，做进一步的查询。如此反复多次，每次都更接近目标的授权服务器，直至得到最后的结果——目标的IP地址或错误信息。<br>因此，根域名服务器采用迭代查询，中介域名服务器采用递归查询。","multi":0,"questionType":1,"answer":"A","chooseItem":["796237659138707457"],"itemList":[{"id":"796237659138707457","questionId":"796237658245320705","content":" 根域名服务器采用迭代查询，中介域名服务器采用递归查询","answer":1,"chooseValue":"A"},{"id":"796237659155484673","questionId":"796237658245320705","content":" 根域名服务器采用递归查询，中介域名服务器采用迭代查询","answer":0,"chooseValue":"B"},{"id":"796237659168067585","questionId":"796237658245320705","content":" 根域名服务器和中介域名服务器均采用迭代查询","answer":0,"chooseValue":"C"},{"id":"796237659176456193","questionId":"796237658245320705","content":" 根域名服务器和中介域名服务器均采用递归查询","answer":0,"chooseValue":"D"}],"userAnswer":null,"userChooseItem":null,"answerCorrect":null,"userCollect":null},{"id":"796237692957380609","title":"关于网桥和交换机，下面的描述中正确的是（69）。","analyze":"网桥和交换机都是第二层转发设备，即都是根据数据链路层地址转发（包括广播）数据包。二者的区别是网桥的端口数较少，一般是用主机插入多个网卡来连接多个子网， 并通过软件来实现分组过滤功能。而交换机通常是采用专门的硬件实现，端口数较多。 由于采用了专用硬件，因此交换机转发速度更快。无论网桥或交换机，一个端口就是一个冲突域。","multi":0,"questionType":1,"answer":"C","chooseItem":["796237693980790785"],"itemList":[{"id":"796237693888516097","questionId":"796237692957380609","content":" 网桥端口数少，因而比交换机转发更快","answer":0,"chooseValue":"A"},{"id":"796237693938847745","questionId":"796237692957380609","content":" 网桥转发广播帧，而交换机不转发广播帧","answer":0,"chooseValue":"B"},{"id":"796237693980790785","questionId":"796237692957380609","content":" 交换机是一种多端口网桥","answer":1,"chooseValue":"C"},{"id":"796237694018539521","questionId":"796237692957380609","content":" 交换机端口多，因而扩大可冲突域的大小","answer":0,"chooseValue":"D"}],"userAnswer":null,"userChooseItem":null,"answerCorrect":null,"userCollect":null},{"id":"796237577177812993","title":"(65)不是设备选型时应考虑的主要原则。","analyze":"在物理网络设计阶段，根据需求说明书、通信规范说明书和逻辑网络设计说明书选择设备的品牌和型号的工作，是较为关键的任务之一。<br>在进行设备的品牌、型号的选择时，应该考虑到产品技术指标、成本因素、原有设备的兼容性、产品的延续性、设备可管理性、厂商的技术支持等多方面的内容。但在选择设备时，并不是把是否采用最新技术作为储运好的衡量标准。","multi":0,"questionType":1,"answer":"D","chooseItem":["796237578155085825"],"itemList":[{"id":"796237578067005441","questionId":"796237577177812993","content":" 技术指标","answer":0,"chooseValue":"A"},{"id":"796237578092171265","questionId":"796237577177812993","content":" 成本因素","answer":0,"chooseValue":"B"},{"id":"796237578121531393","questionId":"796237577177812993","content":" 原有设备的兼容性","answer":0,"chooseValue":"C"},{"id":"796237578155085825","questionId":"796237577177812993","content":" 采用最新技术","answer":1,"chooseValue":"D"}],"userAnswer":null,"userChooseItem":null,"answerCorrect":null,"userCollect":null},{"id":"796237603400601601","title":"IEEE 802.1x是一种（）认证协议。","analyze":"IEEE802.1X协议实现基于端口(MAC地址(的访问控制。认证系统对连接到链路对端的请求者进行认证。一般在用户接入设备上实现802.1X认证。在认证通过之前，802.1X只允许EAPoL(基于局域网的扩展认证协议(数据通过设备连接的交换机端口；认证通过以后，正常的数据可以顺利地通过以太网端口。","multi":0,"questionType":1,"answer":"C","chooseItem":["796237604348514305"],"itemList":[{"id":"796237604314959873","questionId":"796237603400601601","content":" 用户ID","answer":0,"chooseValue":"A"},{"id":"796237604327542785","questionId":"796237603400601601","content":" 报文","answer":0,"chooseValue":"B"},{"id":"796237604348514305","questionId":"796237603400601601","content":" MAC地址","answer":1,"chooseValue":"C"},{"id":"796237604365291521","questionId":"796237603400601601","content":" SSID","answer":0,"chooseValue":"D"}],"userAnswer":null,"userChooseItem":null,"answerCorrect":null,"userCollect":null},{"id":"796237719549267969","title":"在无线局域网中，AP的作用是（68）。","analyze":"在无线局域网中，AP的作用是无线接入，但通常使用的无线路由器则增加了路由等更加复杂的功能。新标准IEEE 802.1 In提供的最高数据速率可达到300Mb/s，这也是目前 市售的无线接入设备提供的最高数据速率。","multi":0,"questionType":1,"answer":"A","chooseItem":["796237720463626241"],"itemList":[{"id":"796237720463626241","questionId":"796237719549267969","content":" 无线接入","answer":1,"chooseValue":"A"},{"id":"796237720480403457","questionId":"796237719549267969","content":" 用户认证","answer":0,"chooseValue":"B"},{"id":"796237720492986369","questionId":"796237719549267969","content":" 路由选择","answer":0,"chooseValue":"C"},{"id":"796237720501374977","questionId":"796237719549267969","content":" 业务管理","answer":0,"chooseValue":"D"}],"userAnswer":null,"userChooseItem":null,"answerCorrect":null,"userCollect":null},{"id":"796237814340538369","title":"采用DHCP分配IP地址无法做到（66）。","analyze":"本题考查考生对DHCP协议及其工作过程的掌握程度。采用DHCP协议可以自动分配IP地址，便于网络管理员依据上网实际用户数合理、动态地分配地址资源，从而达到减轻工作量的目的。由于IP地址资源的分配是由服务器依据地址池进行分配的，减少了分配地址出错的可能，但地址的分配和域名解析不存在直接的联系，无法做到提高域名解析速度。","multi":0,"questionType":1,"answer":"D","chooseItem":["796237815439446017"],"itemList":[{"id":"796237815401697281","questionId":"796237814340538369","content":" 合理分配IP地址资源","answer":0,"chooseValue":"A"},{"id":"796237815410085889","questionId":"796237814340538369","content":" 减少网管员工作量","answer":0,"chooseValue":"B"},{"id":"796237815422668801","questionId":"796237814340538369","content":" 减少IP地址分配出错可能性","answer":0,"chooseValue":"C"},{"id":"796237815439446017","questionId":"796237814340538369","content":" 提高域名解析速度","answer":1,"chooseValue":"D"}],"userAnswer":null,"userChooseItem":null,"answerCorrect":null,"userCollect":null},{"id":"796237591035793409","title":"DNS服务器在名称解析过程中正确的查询顺序为（66）。","analyze":"DNS服务器在名称解析过程中，首先查询本地缓存，若缓存中没有被查域名的记录则在本区域主域名服务器中进行查找，紧接着査询转发域名服务器，最后是根域名服务器，因此，正确的查询顺序为：本地缓存记录一区域记录一转发域名服务器一根域名服务器。","multi":0,"questionType":1,"answer":"A","chooseItem":["796237592050814977"],"itemList":[{"id":"796237592050814977","questionId":"796237591035793409","content":" 本地缓存记录一区域记录一转发域名服务器一根域名服务器","answer":1,"chooseValue":"A"},{"id":"796237592067592193","questionId":"796237591035793409","content":" 区域记录一本地缓存记录一转发域名服务器一根域名服务器","answer":0,"chooseValue":"B"},{"id":"796237592080175105","questionId":"796237591035793409","content":" 本地缓存记录一区域记录一根域名服务器一转发域名服务器","answer":0,"chooseValue":"C"},{"id":"796237592096952321","questionId":"796237591035793409","content":" 区域记录一本地缓存记录一根域名服务器一转发域名服务器","answer":0,"chooseValue":"D"}],"userAnswer":null,"userChooseItem":null,"answerCorrect":null,"userCollect":null},{"id":"796237698980401153","title":"可以把所有使用DHCP协议获取IP地址的主机划分为不同的类别进行管理。下面的选项列出了划分类别的原则，其中合理的是（70）。","analyze":"动态主机配置协议（DHCP)用于在大型网络中为客户端自动分配IP地址及有关网络参数（默认网关和DNS服务器地址等)。使用DHCP服务器便于进行网络管理，可以节省网络配置的工作量，有效地避免网络地址冲突，还能解决IP地址资源不足的问题。<br>DHCP租约周期是IP地址的有效期。租约周期可长可短，取决于用户的上网环境和工作性质。一般把移动用户划分到租约期较短的管理类，把固定用户划分到租约期较长的管理类，远程访问用户划分到默认路由类。对于服务器主机，则要为其保留固定的IP地址，并且要把保留的IP地址与服务器主机的MAC地址进行绑定。","multi":0,"questionType":1,"answer":"C","chooseItem":["796237699940896769"],"itemList":[{"id":"796237699915730945","questionId":"796237698980401153","content":" 移动用户划分到租约期较长的类","answer":0,"chooseValue":"A"},{"id":"796237699928313857","questionId":"796237698980401153","content":" 固定用户划分到租约期较短的类","answer":0,"chooseValue":"B"},{"id":"796237699940896769","questionId":"796237698980401153","content":" 远程访问用户划分到默认路由类","answer":1,"chooseValue":"C"},{"id":"796237699957673985","questionId":"796237698980401153","content":" 服务器划分到租约期最短的类","answer":0,"chooseValue":"D"}],"userAnswer":null,"userChooseItem":null,"answerCorrect":null,"userCollect":null},{"id":"796237795352924161","title":"<p><strong>请作答第<span style=\"color: red\">1</span>个空。</strong></p>网络设计过程分为逻辑网络设计和物理网络设计两个阶段，各个阶段都要产生相应的文档，下面的选项中，(68)应该属于逻辑网络设计文档，(69)属于物理网络设计文档。","analyze":"一个网络系统从构_思开始，到最后被淘汰的过程称为网络生命周期。一般来说，网络生命周期应包括网络系统的构思和计划、分析和设计、运行和维护的全过程。网络系统的生命周期与软件工程中的软件生命周期类似，首先它是一个循环迭代的过程，每次循环迭代的动力都来自于网络应用需求的变更。其次，每次循环过程中，都存在需求分析、规划设计、实施调试和运营维护等多个阶段。一般来说，网络规模越大，则可能经历的循环周期也越长。<br>每一个迭代周期都是网络重构的过程，不同的网络设计方法，对迭代周期的划分方式是不同的，拥有不同的网络文档模板，但是实施后的效果都满足了用户的网络需求。常见的迭代周期构成可分为5个阶段：需求规范、通信规范、逻辑网络设计、物理网络设计和实施阶段。<br>在5个阶段中，每个阶段都是一个工作环节，每个环节完毕后才能进入到下一个环节，类似于软件工程中的“瀑布模型”，形成了特定的工作流程。按照这种流程构建网络，在下一个阶段开始之前，前一阶段的工作已经完成，一般情况下，不允许返回到前面的 阶段。<br>集中访谈和收集信息资料属于需求分析阶段，网络内部通信流量分析属于通信规范阶段，网络IP地址分配方案的制定属于逻辑网络设计阶段，建立设备列表属于物理网络设计阶段。","multi":0,"questionType":1,"answer":"A","chooseItem":["796237796279865345"],"itemList":[{"id":"796237796279865345","questionId":"796237795352924161","content":" 网络IP地址分配方案","answer":1,"chooseValue":"A"},{"id":"796237796313419777","questionId":"796237795352924161","content":" 设备列表清单","answer":0,"chooseValue":"B"},{"id":"796237796342779905","questionId":"796237795352924161","content":" 集中访谈的信息资料","answer":0,"chooseValue":"C"},{"id":"796237796367945729","questionId":"796237795352924161","content":" 网络内部的通信流量分布","answer":0,"chooseValue":"D"}],"userAnswer":null,"userChooseItem":null,"answerCorrect":null,"userCollect":null},{"id":"796237740189437953","title":"建筑物综合布线系统中的园区子系统是指（70）。","analyze":"结构化综合布线系统（Structure Cabling System)是基于现代计算机技术的通信物理平台，集成了语音、数据、图像和视频的传输功能，消除了原有通信线路在传输介质上的差别。<br>结构化布线系统分为6个子系统：工作区子系统、水平子系统、干线子系统、设备间子系统、管理子系统和建筑群子系统。<br>①工作区子系统（WorkLocation)。<br>工作区子系统是由终端设备到信息插座的整个区域。一个独立的需要安装终端设备的区域划分为一个工作区。工作区应支持电话、数据终端、计算机、电视机、监视器以及传感器等多种终端设备。<br>②水平布线子系统（Horizontal)。<br>各个楼层接线间的配线架到工作区信息插座之间所安装的线缆属于水平子系统。水平子系统的作用是将干线子系统线路延伸到用户工作区。<br>③管理子系统（Administration)<br>管理子系统设置在楼层的接线间内，由各种交连设备（双绞线跳线架、光纤跳线架）以及集线器和交换机等交换设备组成，交连方式取决于网络拓扑结构和工作区设备的要求。<br>④干线子系统（Backbone)。<br>干线子系统是建筑物的主干线缆，实现各楼层设备间子系统之间的互连。<br>⑤设备间子系统（Equipment)。<br>建筑物的设备间是网络管理人员值班的场所，设备间子系统由建筑物的进户线、交换设备、电话、计算机、适配器以及保安设施组成，实现中央主配线架与各种不同设备(如PBX、网络设备和监控设备等）之间的连接。<br>⑥建筑群子系统（Campus)。<br>建筑群子系统也叫园区子系统，它是连接各个建筑物的通信系统。","multi":0,"questionType":1,"answer":"D","chooseItem":["796237741162516481"],"itemList":[{"id":"796237741107990529","questionId":"796237740189437953","content":" 由终端到信息插座之间的连线系统","answer":0,"chooseValue":"A"},{"id":"796237741124767745","questionId":"796237740189437953","content":" 楼层接线间到工作区的线缆系统","answer":0,"chooseValue":"B"},{"id":"796237741141544961","questionId":"796237740189437953","content":" 各楼层设备之间的互连系统","answer":0,"chooseValue":"C"},{"id":"796237741162516481","questionId":"796237740189437953","content":" 连接各个建筑物的通信系统","answer":1,"chooseValue":"D"}],"userAnswer":null,"userChooseItem":null,"answerCorrect":null,"userCollect":null},{"id":"796237701887053825","title":"在IEEE 802.11标准中使用了扩频通信技术，以下关于扩频通信的叙述中，正确的是（68）.","analyze":"IEEE 802.11 WLAN中使用了扩展频谱通信技术，这种技术的特点是将信号散布到更宽的频带上以减少发生阻塞和干扰的机会。有两种扩频方式，一种是频率跳动扩频(Frequency Hopping Spread Spectrum, FHSS),另外一种是直接序列扩频（Direct Sequence Spread Spectrum, DSSS)。<br>下图表示各种扩展频谱系统的共同特点。输入数据首先进入信道编码器，产生一个接近某中央频谱的较窄带宽的模拟信号。再用一个伪随机序列对这个信号进行调制。调制的结果是大大拓宽了信号的带宽，即扩展了频谱。在接收端，使用同样的伪随机序列来恢复原来的信号，最后再进入信道解码器来恢复数据。<br><img alt=\"\" width=\"443\" height=\"79\" src=\"https://image.chaiding.com/ruankao/97f98fa2631aefac5330b6f52af42909.jpg?x-oss-process=style/ruankaodaren\"><br>伪随机序列由一个使用初值（称为种子seed)的算法产生。算法是确定的，因此产生的数字序列并不是统计随机的。但如果算法设计得好，得到的序列还是能够通过各种随机性测试的，这就是被叫做伪随机序列的原因。除非你知道算法与种子，否则预测序列是不可能的。因此只有与发送器共享一个伪随机序列的接收器才能对信号进行解码。","multi":0,"questionType":1,"answer":"B","chooseItem":["796237702788829185"],"itemList":[{"id":"796237702776246273","questionId":"796237701887053825","content":" 扩频技术是一种带宽很宽的红外线通信技术","answer":0,"chooseValue":"A"},{"id":"796237702788829185","questionId":"796237701887053825","content":" 扩频技术是一种使用伪随机序列对代表数据的模拟信号进行调制的技术","answer":1,"chooseValue":"B"},{"id":"796237702801412097","questionId":"796237701887053825","content":" 扩频通信系统的带宽随着数据速率的提高而不断扩大","answer":0,"chooseValue":"C"},{"id":"796237702813995009","questionId":"796237701887053825","content":" 扩频技术就是扩大了频率许可证的使用范围","answer":0,"chooseValue":"D"}],"userAnswer":null,"userChooseItem":null,"answerCorrect":null,"userCollect":null},{"id":"796237783659204609","title":"网络的可用性是指（64）。","analyze":"可用性是指网络系统、网络元素或网络应用对用户可利用的时间的百分比。有些应用对可用性很敏感，例如飞机订票系统若宕机一小时，就可能减少几十万元的票款；而股票交易系统如果中断运行一分钟，就可能造成几千万元的损失。实际上，可用性是网络元素可靠性的表现，而可靠性是指网络元素在具体条件下完成特定功能的概率。如果用平均无故障时间（Mean Time Between Failure，MTBF)来度量网络兀素的故障率，则可用性A可表示为MTBF的函数：<br><img alt=\"\" width=\"139\" height=\"43\" src=\"https://image.chaiding.com/ruankao/997d8e42df005d9b0cf100c438ab7fd3.jpg?x-oss-process=style/ruankaodaren\"><br>其中MTTR (Mean Time To Repair)为发生失效后的平均维修时间。由于网络系统由许多网络元素组成，因此系统的可靠性不但与各个元素的可靠性有关，而且还与网络元素的组织形式有关。根据可靠性理论，由元素串并联组成的系统的可用性与网络元素的可用性之间的关系如下图所示。<br><img alt=\"\" width=\"403\" height=\"110\" src=\"https://image.chaiding.com/ruankao/bbd0d394827650c267969dc0ef19e1e5.jpg?x-oss-process=style/ruankaodaren\"><br>从图a可以看出，若两个元素串联，则可用性减少。例如两个Modem串联在链路的两端，若单个Modem的可用性A=0.98,并假定链路其他部分的可用性为1，则整个链路的可用性A=0.98x0.98=0.9604。从图b可以看出，若两个元素并联，则可用性增加。例如终端通过两条链路连接到主机，若一条链路失效，另外一条链路自动备份。假定单个链路的可用性 A=0.98，则双链路的可用性 A=2x0.98-0.98x0.98=1.96-0.9604=0.9996。","multi":0,"questionType":1,"answer":"D","chooseItem":["796237784586145793"],"itemList":[{"id":"796237784556785665","questionId":"796237783659204609","content":" 网络通信能力的大小","answer":0,"chooseValue":"A"},{"id":"796237784569368577","questionId":"796237783659204609","content":" 用户用于网络维修的时间","answer":0,"chooseValue":"B"},{"id":"796237784577757185","questionId":"796237783659204609","content":" 网络的可靠性","answer":0,"chooseValue":"C"},{"id":"796237784586145793","questionId":"796237783659204609","content":" 网络可供用户使用的时间百分比","answer":1,"chooseValue":"D"}],"userAnswer":null,"userChooseItem":null,"answerCorrect":null,"userCollect":null},{"id":"796237650984980481","title":"中国自主研发的3G通信标准是（68）。","analyze":"1985年，ITU提出了对第三代移动通信标准的需求，1996年正式命名为IMT-2000 (International Mobile Telecommunications-2000 )，其中的2000有3层含义：<br>（1）使用的频段在2000mHz附近；<br>（2）通信速率于约为2000Kb/s (即2Mb/s);<br>（3）预期在2000年推广商用。<br>1999年ITU批准了五个IMT-2000的无线电接口，这五个标准是：<br>（1）IMT-DS(Direct Spread)：即W-CDMA，属于频分双工模式，在日本和欧洲制定的UMTS系统中使用；<br>（2）IMT-MC(Multi-Carrier)：即CDMA-2000,属于频分双工模式，是第二代CDMA 系统的继承者；<br>（3）IMT-TC(Time-Code)：这一标准是中国提出的TD-SCDMA，属于时分双工模式；<br>（4）IMT-SC(Single Carrier)：也称为EDGE,是一种2.75G技术；<br>（5）IMT-FT(FrequencyTime)：也称为DECT。<br>2007年10月19日，ITU会议批准移动WiMAX作为第6个3G标准，称为IMT-2000 OFDMATDD WMAN,即无线城域网技术。<br>第三代数字蜂窝通信系统提供第二代蜂窝通信系统提供的所有业务类型，并支持移动多媒体业务。在高速车辆行驶时支持144Kb/s的数据速率，步行和慢速移动环境下支持384Kb/s的数据速率，室内静止环境下支持2Mb/s的高速数据传输，并保证可靠的服务质量。","multi":0,"questionType":1,"answer":"B","chooseItem":["796237651920310273"],"itemList":[{"id":"796237651907727361","questionId":"796237650984980481","content":" CDMA2000","answer":0,"chooseValue":"A"},{"id":"796237651920310273","questionId":"796237650984980481","content":" TD-SCDMA","answer":1,"chooseValue":"B"},{"id":"796237651932893185","questionId":"796237650984980481","content":" WCDMA","answer":0,"chooseValue":"C"},{"id":"796237651949670401","questionId":"796237650984980481","content":" WiMAX","answer":0,"chooseValue":"D"}],"userAnswer":null,"userChooseItem":null,"answerCorrect":null,"userCollect":null},{"id":"796237638217519105","title":"下列关于DHCP的说法中，错误的是（70）。","analyze":"本试题考查DHCP协议及服务器的配置。<br>Windows操作系统中，DHCP提供的IP地址的默认租约期是8天；在有多个DHCP服务器响应时，客户机通常选择最先响应的DHCP服务器提供的地址；客户机可以通过中继代理跨网段申请DHCP服务器提供的IP地址；客户机一直使用DHCP服务器分配给它的IP地址，在租约期50%时开始请求更新租约。","multi":0,"questionType":1,"answer":"D","chooseItem":["796237639136071681"],"itemList":[{"id":"796237639106711553","questionId":"796237638217519105","content":" Windows操作系统中，默认租约期是8天","answer":0,"chooseValue":"A"},{"id":"796237639115100161","questionId":"796237638217519105","content":" 客户机通常选择最先响应的DHCP服务器提供的地址","answer":0,"chooseValue":"B"},{"id":"796237639127683073","questionId":"796237638217519105","content":" 客户机可以跨网段申请DHCP服务器提供的IP地址","answer":0,"chooseValue":"C"},{"id":"796237639136071681","questionId":"796237638217519105","content":" 客户机一直使用DHCP服务器分配给它的IP地址，直至租约期结束才开始联系更新租约","answer":1,"chooseValue":"D"}],"userAnswer":null,"userChooseItem":null,"answerCorrect":null,"userCollect":null},{"id":"796237805838684161","title":"若计算机采用CRC进行差错校验，生成多项式为G（X）=X<sup>4</sup>+X+1，信息字为10110, 则CRC校验码是（14）。","analyze":"本题考査数据校验知识。<br>CRC即循环冗余校验码（Cyclic Redundancy Check)是数据通信领域中最常用的一种差错校验码，其特征是信息字段和校验字段的长度可以任意选定。<br>在CRC校验方法中，进行多项式除法（模2除法）运算后的余数为校验字段。<br>信息字为10110,对应的多项式M(x)=x<sup>4</sup>+x<sup>2</sup>+x，生成多项式为G（X）=X<sup>4</sup>+X+1，对应的代码为10011。<br>校验码计算过程为：先将信息码左移4位（生成码长-1)，得到101100000,然后反复进行异或运算（即除数和被除数最高位对齐，按位异或），如下所示：<br>10110<a href=\"https://image.chaiding.com/ruankao/c0abb8bde067f9f368ded9b4ee5423b4.jpg?x-oss-process=style/ruankaodaren?x-oss-process=style/ruankaodaren?x-oss-process=style/ruankaodaren?x-oss-process=style/ruankaodaren?x-oss-process=style/ruankaodaren?x-oss-process=style/ruankaodaren?x-oss-process=style/ruankaodaren?x-oss-process=style/ruankaodaren?x-oss-process=style/ruankaodaren\" target=\"_blank\"></a><a href=\"https://image.chaiding.com/ruankao/c0abb8bde067f9f368ded9b4ee5423b4.jpg?x-oss-process=style/ruankaodaren?x-oss-process=style/ruankaodaren?x-oss-process=style/ruankaodaren?x-oss-process=style/ruankaodaren?x-oss-process=style/ruankaodaren?x-oss-process=style/ruankaodaren?x-oss-process=style/ruankaodaren?x-oss-process=style/ruankaodaren?x-oss-process=style/ruankaodaren\" target=\"_blank\"></a><img alt=\"\" width=\"13\" height=\"20\" src=\"https://image.chaiding.com/ruankao/c0abb8bde067f9f368ded9b4ee5423b4.jpg?x-oss-process=style/ruankaodaren?x-oss-process=style/ruankaodaren?x-oss-process=style/ruankaodaren?x-oss-process=style/ruankaodaren?x-oss-process=style/ruankaodaren?x-oss-process=style/ruankaodaren?x-oss-process=style/ruankaodaren?x-oss-process=style/ruankaodaren?x-oss-process=style/ruankaodaren\">10011 = 00101，00101 左移两位得到 10100再与 10011 异或；<br>10110<a href=\"https://image.chaiding.com/ruankao/c0abb8bde067f9f368ded9b4ee5423b4.jpg?x-oss-process=style/ruankaodaren?x-oss-process=style/ruankaodaren?x-oss-process=style/ruankaodaren?x-oss-process=style/ruankaodaren?x-oss-process=style/ruankaodaren?x-oss-process=style/ruankaodaren?x-oss-process=style/ruankaodaren?x-oss-process=style/ruankaodaren?x-oss-process=style/ruankaodaren\" target=\"_blank\"></a><a href=\"https://image.chaiding.com/ruankao/c0abb8bde067f9f368ded9b4ee5423b4.jpg?x-oss-process=style/ruankaodaren?x-oss-process=style/ruankaodaren?x-oss-process=style/ruankaodaren?x-oss-process=style/ruankaodaren?x-oss-process=style/ruankaodaren?x-oss-process=style/ruankaodaren?x-oss-process=style/ruankaodaren?x-oss-process=style/ruankaodaren?x-oss-process=style/ruankaodaren\" target=\"_blank\"></a><img alt=\"\" width=\"13\" height=\"20\" src=\"https://image.chaiding.com/ruankao/c0abb8bde067f9f368ded9b4ee5423b4.jpg?x-oss-process=style/ruankaodaren?x-oss-process=style/ruankaodaren?x-oss-process=style/ruankaodaren?x-oss-process=style/ruankaodaren?x-oss-process=style/ruankaodaren?x-oss-process=style/ruankaodaren?x-oss-process=style/ruankaodaren?x-oss-process=style/ruankaodaren?x-oss-process=style/ruankaodaren\">10011 = 00101，00101 左移两位得到 10100再与 10011 异或；<br>11100<a href=\"https://image.chaiding.com/ruankao/c0abb8bde067f9f368ded9b4ee5423b4.jpg?x-oss-process=style/ruankaodaren?x-oss-process=style/ruankaodaren?x-oss-process=style/ruankaodaren?x-oss-process=style/ruankaodaren?x-oss-process=style/ruankaodaren?x-oss-process=style/ruankaodaren?x-oss-process=style/ruankaodaren?x-oss-process=style/ruankaodaren?x-oss-process=style/ruankaodaren\" target=\"_blank\"></a><a href=\"https://image.chaiding.com/ruankao/c0abb8bde067f9f368ded9b4ee5423b4.jpg?x-oss-process=style/ruankaodaren?x-oss-process=style/ruankaodaren?x-oss-process=style/ruankaodaren?x-oss-process=style/ruankaodaren?x-oss-process=style/ruankaodaren?x-oss-process=style/ruankaodaren?x-oss-process=style/ruankaodaren?x-oss-process=style/ruankaodaren?x-oss-process=style/ruankaodaren\" target=\"_blank\"></a><img alt=\"\" width=\"13\" height=\"20\" src=\"https://image.chaiding.com/ruankao/c0abb8bde067f9f368ded9b4ee5423b4.jpg?x-oss-process=style/ruankaodaren?x-oss-process=style/ruankaodaren?x-oss-process=style/ruankaodaren?x-oss-process=style/ruankaodaren?x-oss-process=style/ruankaodaren?x-oss-process=style/ruankaodaren?x-oss-process=style/ruankaodaren?x-oss-process=style/ruankaodaren?x-oss-process=style/ruankaodaren\">10011 = 01111，其结果iCRC 校验码，即余数 1111。","multi":0,"questionType":1,"answer":"D","chooseItem":["796237806945980417"],"itemList":[{"id":"796237806912425985","questionId":"796237805838684161","content":" 0000","answer":0,"chooseValue":"A"},{"id":"796237806925008897","questionId":"796237805838684161","content":" 0100","answer":0,"chooseValue":"B"},{"id":"796237806933397505","questionId":"796237805838684161","content":" 0010","answer":0,"chooseValue":"C"},{"id":"796237806945980417","questionId":"796237805838684161","content":" 1111","answer":1,"chooseValue":"D"}],"userAnswer":null,"userChooseItem":null,"answerCorrect":null,"userCollect":null},{"id":"796237771629940737","title":"确定网络的层次结构及各层采用的协议是网络设计中（66）阶段的主要任务。","analyze":"确定网络的层次结构及各层采用的协议是网络设计中网络体系结构设计阶段的主要任务。","multi":0,"questionType":1,"answer":"B","chooseItem":["796237772745625601"],"itemList":[{"id":"796237772728848385","questionId":"796237771629940737","content":" 网络需求分析","answer":0,"chooseValue":"A"},{"id":"796237772745625601","questionId":"796237771629940737","content":" 网络体系结构设计","answer":1,"chooseValue":"B"},{"id":"796237772758208513","questionId":"796237771629940737","content":" 网络设备选型","answer":0,"chooseValue":"C"},{"id":"796237772770791425","questionId":"796237771629940737","content":" 网络安全性设计","answer":0,"chooseValue":"D"}],"userAnswer":null,"userChooseItem":null,"answerCorrect":null,"userCollect":null},{"id":"796237582835929089","title":"4G移动通信标准TD-LTE与LTE FDD的区别是（）。","analyze":"4G移动通信标准TD-LTE(即TDD-LTE).与FDD-LTE的主要区别是划分上下行信道的方式不同，前者用时分多路方式，而后者用频分多路方式。其他方面大同小异。","multi":0,"questionType":1,"answer":"B","chooseItem":["796237583909670913"],"itemList":[{"id":"796237583901282305","questionId":"796237582835929089","content":" 频率的利用方式不同","answer":0,"chooseValue":"A"},{"id":"796237583909670913","questionId":"796237582835929089","content":" 划分上下行信道的方式不同","answer":1,"chooseValue":"B"},{"id":"796237583926448129","questionId":"796237582835929089","content":" 采用的调制方式有区别","answer":0,"chooseValue":"C"},{"id":"796237583943225345","questionId":"796237582835929089","content":" 拥有专利技术的厂家不同","answer":0,"chooseValue":"D"}],"userAnswer":null,"userChooseItem":null,"answerCorrect":null,"userCollect":null},{"id":"796237780639305729","title":"网络故障需按照协议层次进行分层诊断，找出故障原因并进行相应处理。查看端口状态、协议建立状态和EIA状态属于（64）诊断。","analyze":"网络故障需按照协议层次进行分层诊断，找出故障原因并进行相应处理。<br>物理层是OSI分层结构体系中最基础的一层，它建立在通信媒体的基础上，实现系统和通信媒体的物理接口，为数据链路实体之间进行透明传输，为建立、保持和拆除计算机和网络之间的物理连接提供服务。<br>物理层的故障主要表现在设备的物理连接方式是否恰当；连接电缆是否正确。确定路由器端口物理连接是否完好的最佳方法是使用show interface命令，检査每个端口的状态，解释屏幕输出信息，查看端口状态、协议建立状态和EIA状态。","multi":0,"questionType":1,"answer":"A","chooseItem":["796237781528498177"],"itemList":[{"id":"796237781528498177","questionId":"796237780639305729","content":" 物理层","answer":1,"chooseValue":"A"},{"id":"796237781541081089","questionId":"796237780639305729","content":" 数据链路层","answer":0,"chooseValue":"B"},{"id":"796237781557858305","questionId":"796237780639305729","content":" 网络层","answer":0,"chooseValue":"C"},{"id":"796237781570441217","questionId":"796237780639305729","content":" 应用层","answer":0,"chooseValue":"D"}],"userAnswer":null,"userChooseItem":null,"answerCorrect":null,"userCollect":null},{"id":"796234003710496769","title":"DNS协议的功能是（）。","analyze":"DNS协议（Domain Name System，域名系统）是一种将域名解析为IP地址的分布式数据库系统。在Internet上，每个主机都有一个唯一的IP地址，但是由于IP地址是一串数字，不便记忆，因此人们通常使用域名来代替IP地址访问目标主机。DNS协议就是将域名转换为IP地址的过程，从而方便用户访问Internet上的各种服务。DNS协议具体实现了包括递归查询、迭代查询、缓存等功能，使得DNS系统可以高效、准确地完成域名解析任务。因此，选项A是正确答案。选项B所描述的是ARP协议（Address Resolution Protocol，地址解析协议）的功能；选项C所描述的是RARP协议（Reverse Address Resolution Protocol，反向地址解析协议）的功能；选项D中的“主机名”和“域名”有所区别，主机名通常指局域网内的主机名称，而不是全局的域名。\n\n\n\n\n","multi":0,"questionType":1,"answer":"A","chooseItem":["796234004712935425"],"itemList":[{"id":"796234004712935425","questionId":"796234003710496769","content":" 将域名解析为IP地址","answer":1,"chooseValue":"A"},{"id":"796234004746489857","questionId":"796234003710496769","content":" 将MAC地址解析为IP地址","answer":0,"chooseValue":"B"},{"id":"796234004771655681","questionId":"796234003710496769","content":" 将IP地址解析为MAC地址","answer":0,"chooseValue":"C"},{"id":"796234004792627201","questionId":"796234003710496769","content":" 将主机名解析为IP地址","answer":0,"chooseValue":"D"}],"userAnswer":null,"userChooseItem":null,"answerCorrect":null,"userCollect":null},{"id":"796234014166896641","title":"IP地址10.10.33.66/16的网络地址是（）。","analyze":"网络地址是将一个IP地址和子网掩码进行与运算得到的结果，其实现过程是将IP地址和子网掩码中相同位置上的二进制位进行&操作。\n<br>\n将IP地址10.10.33.66和子网掩码/16（即255.255.0.0）进行与运算，得到的结果是10.10.0.0。因此，答案为 A. 10.10.0.0。\n<br>\n综上所述，本题答案为 A. 10.10.0.0。","multi":0,"questionType":1,"answer":"A","chooseItem":["796234015077060609"],"itemList":[{"id":"796234015077060609","questionId":"796234014166896641","content":" 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生存时间","answer":0,"chooseValue":"C"},{"id":"796234018541555713","questionId":"796234017346179073","content":" 源/目的IP","answer":0,"chooseValue":"D"}],"userAnswer":null,"userChooseItem":null,"answerCorrect":null,"userCollect":null},{"id":"796235040047517697","title":"循环冗余校验码（Cyclic Redundancy Check ，CRC)是数据通信领域中最常用的一种差错校验码，该校验方法中，使用多项式除法（模2除法）运算后的余数为校验字段。若数据信息为n位，则将其左移k位后，被长度为k+1位的生成多项式相除，所得的k位余数即构成k 个校验位，构成n+k位编码。若数据信息为1100，生成多项式为X<sup>3</sup>+X+1 (即1011) ，则CRC编码是（ ）。","analyze":"本题考查计算机系统基础知识。<br>用1100000作被除数，1011作除数，进行模2除法，可得商1110和余数10，构成的CRC编码为1100010。","multi":0,"questionType":1,"answer":"A","chooseItem":["796235040982847489"],"itemList":[{"id":"796235040982847489","questionId":"796235040047517697","content":" 1100010","answer":1,"chooseValue":"A"},{"id":"796235041020596225","questionId":"796235040047517697","content":" 1011010","answer":0,"chooseValue":"B"},{"id":"796235041054150657","questionId":"796235040047517697","content":" 1100011","answer":0,"chooseValue":"C"},{"id":"796235041079316481","questionId":"796235040047517697","content":" 1011110","answer":0,"chooseValue":"D"}],"userAnswer":null,"userChooseItem":null,"answerCorrect":null,"userCollect":null},{"id":"796233812269879297","title":"TCP/IP的四层模型中，每一层都提供了安全协议，下列属于网络层安全协议的是（）。","analyze":"HTTPS应用层协议   SSH安全外壳协议，应用层协议    \n</br><br/>\nIPSec网络层协议    Socks防火墙安全会话转换协议，会话层协议","multi":0,"questionType":1,"answer":"C","chooseItem":["796233813335232513"],"itemList":[{"id":"796233813263929345","questionId":"796233812269879297","content":" HTTPS","answer":0,"chooseValue":"A"},{"id":"796233813301678081","questionId":"796233812269879297","content":" SSH","answer":0,"chooseValue":"B"},{"id":"796233813335232513","questionId":"796233812269879297","content":" IPSec","answer":1,"chooseValue":"C"},{"id":"796233813372981249","questionId":"796233812269879297","content":" 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SFTP是可以用于文件安全传输的协议，是本题的答案选项。","multi":0,"questionType":1,"answer":"B","chooseItem":["796234001009364993"],"itemList":[{"id":"796234000980004865","questionId":"796234000015314945","content":" FTP","answer":0,"chooseValue":"A"},{"id":"796234001009364993","questionId":"796234000015314945","content":" SFTP","answer":1,"chooseValue":"B"},{"id":"796234001042919425","questionId":"796234000015314945","content":" TFTP","answer":0,"chooseValue":"C"},{"id":"796234001072279553","questionId":"796234000015314945","content":" ICMP","answer":0,"chooseValue":"D"}],"userAnswer":null,"userChooseItem":null,"answerCorrect":null,"userCollect":null},{"id":"796234006927527937","title":"下列协议中，不属于电子邮件收发协议的是（）。","analyze":"FTP是文件传输协议（File Transfer Protocol），主要用于计算机之间的文件传输和共享。而SMTP、POP和IMAP都是电子邮件收发协议，其中SMTP用于发送邮件，而POP和IMAP用于接收邮件。通常，当我们在邮箱中查看邮件时，就是通过POP或IMAP协议来接收邮件的。因此，选项 D 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在以太网标准中规定的最小帧长是64字节，最小帧长是根据网络中检测冲突的最长时间，为了过滤冲突废帧而设定的。","multi":0,"questionType":1,"answer":"B","chooseItem":["796234714515001345"],"itemList":[{"id":"796234714485641217","questionId":"796234713554505729","content":" 20","answer":0,"chooseValue":"A"},{"id":"796234714515001345","questionId":"796234713554505729","content":" 64","answer":1,"chooseValue":"B"},{"id":"796234714544361473","questionId":"796234713554505729","content":" 128","answer":0,"chooseValue":"C"},{"id":"796234714565332993","questionId":"796234713554505729","content":" 151.8","answer":0,"chooseValue":"D"}],"userAnswer":null,"userChooseItem":null,"answerCorrect":null,"userCollect":null},{"id":"796234717056749569","title":"<p><strong>请作答第<span style=\"color: red\">2</span>个空。</strong></p>在以太网标准中规定的最小帧长是（62）字节，最小帧长是根据（63）来定的。","analyze":"本题考查以太网标准相关知识。<br> 在以太网标准中规定的最小帧长是64字节，最小帧长是根据网络中检测冲突的最长时间，为了过滤冲突废帧而设定的。","multi":0,"questionType":1,"answer":"D","chooseItem":["796234718071771137"],"itemList":[{"id":"796234717992079361","questionId":"796234717056749569","content":" 网络中传送的最小信息单位","answer":0,"chooseValue":"A"},{"id":"796234718017245185","questionId":"796234717056749569","content":" 物理层可以区分的信息长度","answer":0,"chooseValue":"B"},{"id":"796234718054993921","questionId":"796234717056749569","content":" 网络中发生冲突的最短时间","answer":0,"chooseValue":"C"},{"id":"796234718071771137","questionId":"796234717056749569","content":" 网络中检测冲突的最长时间","answer":1,"chooseValue":"D"}],"userAnswer":null,"userChooseItem":null,"answerCorrect":null,"userCollect":null},{"id":"796235194574065665","title":"以下关于光纤的说法中，错误的是（ ）。","analyze":"本题考査传输介质基础知识。<br>和多模光纤相比，单模光纤的纤芯直径更细，传输距离更远，为保障单一模式传输，采用激光作为光源。","multi":0,"questionType":1,"answer":"B","chooseItem":["796235195513589761"],"itemList":[{"id":"796235195484229633","questionId":"796235194574065665","content":" 单模光纤的纤芯直径更细","answer":0,"chooseValue":"A"},{"id":"796235195513589761","questionId":"796235194574065665","content":" 单模光纤采用LED作为光源","answer":1,"chooseValue":"B"},{"id":"796235195542949889","questionId":"796235194574065665","content":" 多模光纤比单模光纤的传输距离近","answer":0,"chooseValue":"C"},{"id":"796235195572310017","questionId":"796235194574065665","content":" 多模光纤中光披在光导纤维中以多种模式传播","answer":0,"chooseValue":"D"}],"userAnswer":null,"userChooseItem":null,"answerCorrect":null,"userCollect":null},{"id":"796234955721035777","title":"主机host1对host2进行域名查询的过程如下图所示，下列说法中正确的是（ ）。<br><img alt=\"\" src=\"https://image.chaiding.com/ruankao/f6929b45c3a2d9a602c03ca2a48e2586.jpg?x-oss-process=style/ruankaodaren\" height=\"275\" 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授权域名服务器采用何种算法不确定","answer":1,"chooseValue":"D"}],"userAnswer":null,"userChooseItem":null,"answerCorrect":null,"userCollect":null},{"id":"796235433250934785","title":"在浏览器的地址栏中输入xxxyftp.abc.com.cn，该URL中（64）是要访问的主机名。","analyze":"本题考查URL知识。<br>一个URL由协议名://主机名.域名/目录名/文件名几部分构成。题目中所给的URL不包含协议名称，按照以上描述，要访问的主机名为xxxyftp，该字段后面的abc.com.cn属于域名。","multi":0,"questionType":1,"answer":"A","chooseItem":["796235434408562689"],"itemList":[{"id":"796235434408562689","questionId":"796235433250934785","content":" xxxyftp","answer":1,"chooseValue":"A"},{"id":"796235434437922817","questionId":"796235433250934785","content":" abc","answer":0,"chooseValue":"B"},{"id":"796235434471477249","questionId":"796235433250934785","content":" com","answer":0,"chooseValue":"C"},{"id":"796235434500837377","questionId":"796235433250934785","content":" 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采用UDP实现网络管理不会太多增加网络负载","answer":1,"chooseValue":"D"}],"userAnswer":null,"userChooseItem":null,"answerCorrect":null,"userCollect":null},{"id":"796234958778683393","title":"<p><strong>请作答第<span style=\"color: red\">1</span>个空。</strong></p>某公司网络的地址是192.168.192.0/20，要把该网络分成32个子网，则对应的子网掩码应该是（65），每个子网可分配的主机地址数是（66）。","analyze":"本题考查IP地址相关知识。<br>将网络地址192.168.192.0/20分成32个子网，需要主机部分中高5位作为子网号，故划分后的子网掩码为25位，即子网掩码为255.255.255.128。此时每个子网的可用主机数为126个。","multi":0,"questionType":1,"answer":"D","chooseItem":["796234959856619521"],"itemList":[{"id":"796234959764344833","questionId":"796234958778683393","content":" 255.255.252.0","answer":0,"chooseValue":"A"},{"id":"796234959793704961","questionId":"796234958778683393","content":" 255.255.254.0","answer":0,"chooseValue":"B"},{"id":"796234959827259393","questionId":"796234958778683393","content":" 255.255.255.0","answer":0,"chooseValue":"C"},{"id":"796234959856619521","questionId":"796234958778683393","content":" 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不使用广播方式更新报文","answer":0,"chooseValue":"D"}],"userAnswer":null,"userChooseItem":null,"answerCorrect":null,"userCollect":null},{"id":"796235439492059137","title":"客户端采用ping命令检测网络连接故障时，可以ping通127.0.0.1及本机的IP地址，但无法ping通同一网段内其他工作正常的计算机的IP地址。该客户端的故障可能是（66）。","analyze":"客户端可以ping通127.0.0.1及本机的IP地址，说明TCP/IP协议工作正常，并且本机的网卡也工作正常，但无法ping通同一网段内其他工作正常的计算机的IP地址，故可以考虑是网络线路故障。由于该检测ping的都是IP地址，所以与DNS服务器无关。","multi":0,"questionType":1,"answer":"C","chooseItem":["796235440653881345"],"itemList":[{"id":"796235440582578177","questionId":"796235439492059137","content":" TCP/IP协议不能正常工作","answer":0,"chooseValue":"A"},{"id":"796235440616132609","questionId":"796235439492059137","content":" 本机网卡不能正常工作","answer":0,"chooseValue":"B"},{"id":"796235440653881345","questionId":"796235439492059137","content":" 本机网络线路故障","answer":1,"chooseValue":"C"},{"id":"796235440691630081","questionId":"796235439492059137","content":" 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存在敏感信息泄漏风险","answer":0,"chooseValue":"C"},{"id":"796234485577306113","questionId":"796234484520341505","content":" 保存访问站点的缓存数据","answer":1,"chooseValue":"D"}],"userAnswer":null,"userChooseItem":null,"answerCorrect":null,"userCollect":null},{"id":"796234961999908865","title":"<p><strong>请作答第<span style=\"color: red\">2</span>个空。</strong></p>某公司网络的地址是192.168.192.0/20，要把该网络分成32个子网，则对应的子网掩码应该是（65），每个子网可分配的主机地址数是（66）。","analyze":"本题考查IP地址相关知识。<br>将网络地址192.168.192.0/20分成32个子网，需要主机部分中高5位作为子网号，故划分后的子网掩码为25位，即子网掩码为255.255.255.128。此时每个子网的可用主机数为126个。","multi":0,"questionType":1,"answer":"B","chooseItem":["796234963065262081"],"itemList":[{"id":"796234963056873473","questionId":"796234961999908865","content":" 62","answer":0,"chooseValue":"A"},{"id":"796234963065262081","questionId":"796234961999908865","content":" 126","answer":1,"chooseValue":"B"},{"id":"796234963077844993","questionId":"796234961999908865","content":" 254","answer":0,"chooseValue":"C"},{"id":"796234963086233601","questionId":"796234961999908865","content":" 510","answer":0,"chooseValue":"D"}],"userAnswer":null,"userChooseItem":null,"answerCorrect":null,"userCollect":null},{"id":"796234487565406209","title":"使用电子邮件客户端从服务器下载邮件，能实现邮件的移动、删除等操作在客户端和邮箱更新同步，所使用的电子邮件接收协议是（67）。","analyze":"本题考查电子邮件协议方面的基础知识。<br> SMTP (Simple Mail Transfer Protocol)即简单邮件传输协议，是一组用于从源地址到目的地址传输邮件的规范，通过它来控制邮件的中转方式。SMTP协议属于TCP/IP协议簇，它帮助每台计算机在发送或中转信件时找到下一个目的地。<br> POP3 (Post Office Protocol 3)是规定怎样将个人计算机连接到Internet的邮件服务器和下载电子邮件的电子协议。它是因特网电子邮件的第一个离线协议标准，POP3允许用户从服务器上把邮件存储到本地主机（即自己的计算机）上，同时删除保存在邮件服务器上的邮件。<br> IMAP4协议与POP3协议一样，也是规定个人计算机如何访问网上的邮件服务器进行收发邮件的协议，但是IMAP4协议同POP3协议相比更高级。IMAP4支持协议客户机在线或者离线访问并阅读服务器上的邮件，还能交互式地操作服务器上的邮件。开启了 IMAP4后， 在电子邮件客户端收取的邮件仍然保留在服务器上，同时在客户端上的操作都会反馈到服务器上，如删除邮件、标记已读等，服务器上的邮件也会做相应的动作。所以无论从浏览器登录邮箱或者客户端软件登录邮箱，看到的邮件以及状态都是一致的。<br> MIME (Multipurpose Internet Mail 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