CCNA考试自测题第1卷(三)(1)-思科认证试题

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思科认证CCNA认证试题和答案中文版

思科认证CCNA认证试题和答案中文版思科认证CCNA认证试题和答案中文版想要获得思科认证，首先要参加由思科推荐并授权的培训中心(Cisco Training Partner，简称CTP)所开设的培训课程。

完成学业后再到由全球考试机构Sylvan Prometric授权的.考试中心参加由思科指定的科目的认证考试。

通过指定的系列科目考试后，学员就可以获得相应分支系列等级的资格认证。

下面是店铺为大家搜集的相关试题，供大家参考练习。

16、路由器A串口0配置如下interface serial0link-protocol pppppp pap local-user huawei password simple quidwayip address 2.2.2.1 255.0.0.0路由器B串口及全局配置如下local-user huawei service-type ppp password simple quidway!interface serial0link-protocol pppppp authentication-mode papip address 2.2.2.2 255.0.0.0当两台路由器串口0相连时，两台路由器是否可以连接到对端()(A) 能(B) 不能答案：A17、关于千兆以太网，以下说法正确的是( )(A) IEEE802.3ab定义了千兆以太网(B) 在同一冲突域中，千兆以太网不允许中继器的互连(C) IEEE802.3z专门定义了千兆以太网在双绞线上的传输标准(D) 千兆以太网支持网络速率的自适应，可以与快速以太网自动协商传输速率答案：AB参考知识点：华为3com认证教材第一册3-8页18、高层的协议将数据传递到网络层后，形成( )，而后传送到数据链路层(A) 数据帧(B) 信元(C) 数据包(D) 数据段答案：C参考知识点：华为3com认证教材第一册1-20页19、在路由器上配置帧中继静态map必须指定( )参数(A) 本地的DLCI(B) 对端的DLCI(C) 本地的协议地址(D) 对端的协议地址答案：AD20、路由器的主要性能指标不包括( )(A) 延迟(B) 流通量(C) 帧丢失率(D) 语音数据压缩比答案：D【思科认证CCNA认证试题和答案中文版】。

思科认证CCNA认证试题与答案中文版

思科认证CCNA认证试题与答案中文版思科认证CCXA认证试题与答案中文版21、一个B类网络，有5位掩码加入缺省掩码用来划分子网，每个子网最多()台主机(A)510(B)512(C)1022(D)2046答案：D22、在路由器中，能用以下命令察看路由器的路由表()(A)arp-a(B)traceroute(C)routeprint(D)displayiprouting-table答案：D23、DHCP客户端是使用地址()来中请一个新的IP地址的(A)0. 0. 0. 0(B)10. 0. 0. 1(0127. 0. 0. 1(D)255. 255. 255. 255答案：D注释:255. 255. 255. 255是全网广播,DHCP客户端发送全网广播来查找DHCP服务器.24、下而有关NAT叙述正确的是()(A)NAT是英文“地址转换”的缩写，又称地址翻译(B)XAT用来实现私有地址与公用网络地址之间的转换(C)当内部网络的主机访问外部网络的时候，一定不需要NAT(D)地址转换的提出为解决IP地址紧张的问题提供了一个有效途径答案:ABD25、以下属于正确的主机的IP地址的是()(A)224. 0. 0.5(B)127. 32. 5. 62(0202. 112.5.0(D) 162. 111. 111. Ill答案：D注释:这个题目不是太严谨,应该加上子网掩码.A:224. 0. 0. 5是多播地址B: 127. 0.0. 0保留作为测试使用C:网络地址26、设置主接口由up转down后延迟30秒切换到备份接口，主接口由down转up后60秒钟切换回主接口的配置为()(A)standbytimer3060(B)standbytimer6030(C)standbytimerenable-delay60disable-delay30(D)standbytimerenable-delay30disable-delay60答案：D27、在一个以太网中，30台pc通过QuidwayR2501路由器s0 口连接internet, QuidwayR2501路由器配置如下：[Quidway-EthernetO] ipaddressl92. 168. 1. 1255. 255. 255. 0[Quidway-EthernetO]quit[Quidway]interfacesO[Quidway-SerialOJ ipaddress211. 136. 3. 6255. 255. 255. 252[Quidway-Serial0」link-protocolppp一台PC机默认网关为192. 168. 2.1,路由器会怎样处理发自这台PC 的数据包？(A)路由器会认为发自这一台PC的数据包不在同一网段，不转发数据包(B)路由器会自动修正这一台PC机的IP地址，转发数据包(C)路由器丢弃数据包，这时候需要重启路由器，路由器自动修正误配(D)路由器丢弃数据包，不做任何处理，需要重配PC网关为192. 168. 1. 1答案：D注释:PC的'默认网关要指向路由器的以太网口的IP地址.28、ISDNB信道速率是()(A)16kbps(B)64kbps(C)144kbps(D)2048kbps答案:B参考知识点：综合数字业务网(ISDN)由数字电话和数据传输服务两部分组成，一般由电话局提供这种服务。

思科认证CCNP经典试题

思科认证CCNP经典试题第一部分填空题1、在Cisco体系的IGP协议中，RIP的A-D管理距离是，EIGRP 的域内A-D管理距离是，EIGRP的域外A-D管理距离是OSPF的A-D管理距离是。

BGP 从EBGP学习到的路由学到路由的A-D管理距离是; BGP从IBGP学习到的路由学到路由的A-D管理距离是。

2、BGP的默认MED值为；其中MED越越优选被用于选路；BGP从邻居哪里学到的权重为；BGP自己本路由产生的路由（始发路由）产生权重是；BGP 的默认本地优先级为：。

3、BGP的邻居分为和。

4、OSPF在那个区域（有区域0，区域1，区域2）广播多路访问（比如以太网，没有出现外部网络），在区域0可以看到类LSA。

如果想看到2类LSA，必须在网络类型；在NSSA区域可以看到类LSA，在纯粹的NASS区域内是否有5类LSA？（回答是或者否）。

5、HSRP包括哪六种状态？6、OSPF在MA网络链路类型的HELLO报文作用？（3种）7、IPV6的本地链路地址是；本地站点地址是。

（没有/10的写法）8、在选择STP的角色（身份）有哪些？，默认STP的收敛时间为。

配置了portfast后，收敛时间会小于。

9、OSPF发送hello包的组播地址是，EIGRP组播地址是；HSRP 发送hello包组播地址是；VRRP发送hello 包的组播地址是。

10、目前以太通道最多可以使用条物理线缆逻辑捆绑成一个以太通道接口？形成以太通道方式有。

11、BGP在EBGP中使用属性避免AS间的环路（确保无环），该属性属于BGP的必遵属性，其中还有哪两个是BGP公认必遵属性为和。

第二部分选择1、在对基于CEF的多层交换（MLS）进行排错的时候，例如解决无法到达特定的IP目标等问题，首先需要先查看哪两张表去验证错误？（）A、IP路由表和路由表B、IP路由和CEF邻接关系表C、TCAM中的IP CEF FIB和邻接关系表D、IP路由表和ARP表2、EIGRP位一个混合距离矢量协议，在METRIC值中使用K1-K5五个K值，默认情况下，使用K值分别是（）A、K1，K2 B K3,K4 C、K1，K5 D、K1，K33、OSPF中router-id能标识一台设备的身份，下面说法正确的是（）A、先选举手工配置，然后选择设备loopback地址大的，在选运行了宣告进OSPF最大的物理接口最大的地址。

思科题目

CCNACCNA11章节考试题之01《生活在以网络为中心的世界》1、在主要使用文本相互通信的两人或多人之间，他们使用的哪种通信形式属于基于文本的实时通信？A.网络日志B.维基C.即时消息D.播客E.协作工具2、哪种网络为客户提供对企业数据（如库存、部件列表和订单）的有限访问？A.内部网B.外联网C.网际网络D.Internet3、出于管理数据的目的，需要使用什么来权衡通信的重要性及其特征？A.网络管理B.网络流量C.QoS策略D.网络评估4、对网络通信采取哪些处理后才能使服务质量策略正常发挥作用？（选择两项）A.根据服务质量要求对通信分类。

B.对应用程序数据的每个分类分配优先级。

C.始终对Web通信分配高优先级处理队列。

D.始终对数字电影分配高优先级处理队列。

E.始终对电子邮件通信分配低优先级队列。

5、网络体系结构有哪两个部分？（选择两项）A.构成以人为本网络的人B.通过网络传输消息的编程服务和协议C.通过网络传输的数据D.支持网络通信的技术E.运营和维护数据网络的企业6、在当初开发Internet时，放弃面向连接的电路交换技术出于哪三个原因？（选三项）A.电路交换技术要求将单个消息划分为包含编址信息的多个消息。

B.早期的电路交换网络在电路出现故障时不能自动建立备用链路。

C.电路交换技术要求即使两个位置之间当前并未传输数据，也必须在网络端点之间建立开放电路。

D.通过面向连接的电路交换网络传输消息无法保证质量和一致性。

E.建立多路并发开放电路获得容错能力成本高昂。

7、开发Internet时使用数据包交换无连接数据通信技术出于哪三个原因？（选三项）A.它能快速适应数据传输设施的丢失。

B.它能有效利用网络基础架构传输数据。

C.数据包可同时通过网络采取多条路径传输。

D.支持按建立连接的时间收取网络使用费用。

E.传输数据之前需要在源设备和目的设备之间建立数据电路。

8、QoS在融合网络中的作用是什么?A.确保丢弃高于可用带宽水平的所有通信B.确定网络中不同通信的传输优先级C.针对所有网络通信确定精确的优先级D.允许网络中的其它组织共享未使用的带宽9、将左侧的选项和右侧的对象连线，使网络体系结构的特征与其定义相匹配。

CCNA认证试题-15页word资料

CCNA认证试题一（附答案和解析）中文版一) 认证试题一（附答案和解析）中文版(一CCNA1 2019-09-30 15:49:59 阅读139 评论0 字号：大中小订阅1、目前，我国应用最为广泛的LAN 标准是基于（）的以太网标准. (A) IEEE 802.1 (B) IEEE 802.2 (C) IEEE 802.3 (D) IEEE 802.5 答案：C 参考知识点：现有标准：IEEE 802.1 局域网协议高层IEEE 802.2 逻辑链路控制IEEE 802.3 以太网IEEE 802.4 令牌总线IEEE 802.5 令牌环IEEE 802.8 FDDI IEEE 802.11 无线局域网记住IEEE802.1-------IEEE802.5 的定义以太网是一种计算机局域网组网技术IEEE 制定的IEEE 802.3 标准给出了以太。

网的技术标准。

它规定了包括物理层的连线、电信号和介质访问层协议的内容。

以太网是当前应用最普遍的局域网技术。

它很大程度上取代了其他局域网标准，如令牌环、FDDI 和ARCNET。

以太网的标准拓扑结构为总线型拓扑，但目前的快速以太网（100BASE-T、1000BASE-T 标准）为了最大程度的减少冲突，最大程度的提高网络速度和使用效率，使用交换机（Switch）来进行网络连接和组织，这样，以太网的拓扑结构就成了星型，但在逻辑上，以太网仍然使用总线型拓扑的C***A/CD 介质访问控制方法。

电气电子工程师协会或IEEE（Institute of Electrical and Electronics Engineers）是一个国际性的电子技术与信息科学工程师的协会。

建会于1963 年1 月1 日。

总部在美国纽约市。

在150 多个国家中它拥有300 多个地方分会。

目前会员数是36 万。

专业上它有35 个专业学会和两个联合会。

IEEE 发表多种杂志，学报，书籍和每年组织300 多次专业会议。

ccna考试题库最新版

ccna考试题库最新版CCNA（Cisco Certified Network Associate）认证是全球范围内最受欢迎的网络工程师认证之一，具备CCNA认证可以证明一个人在建立、规划、运行、安装和配置中等规模的局域网和广域网方面的专业知识。

为了帮助广大考生顺利通过CCNA考试，不断更新的CCNA考试题库至关重要。

以下是最新版本的CCNA考试题库，希望对考生们有所帮助。

第一部分：网络基础知识1. 什么是OSI七层模型？简要介绍每一层的功能。

2. TCP和UDP之间有哪些区别？请分别举例说明。

3. 什么是IP地址？IP地址的类型有哪些？请列举并简要介绍各自的特点。

4. 什么是子网掩码？为什么在网络中使用子网掩码？5. 简述常见的网络设备有哪些，以及各自的功能与作用。

第二部分：路由和交换技术1. 路由器和交换机之间有何区别？请进行比较并指出各自的优势和劣势。

2. 什么是VLAN？VLAN的作用及在网络中的应用场景是什么？3. OSPF和EIGRP是两种常见的路由协议，请比较它们的特点并举例说明。

4. 请解释静态路由和动态路由的概念以及在网络中的应用。

5. 交换机在网络中扮演什么角色？交换机的MAC地址表是如何工作的？第三部分：网络安全和管理1. 网络安全的重要性是什么？请列举几种常见的网络安全威胁并介绍应对策略。

2. 什么是ACL（访问控制列表）？ACL的作用是什么？请给出一个ACL的配置示例。

3. VPN是什么？VPN的工作原理及在企业网络中的应用。

4. SNMP是网络管理中常用的协议，它的作用是什么？请解释SNMP中的几个重要概念。

5. 如何保护无线网络的安全？请列举几种方法。

第四部分：WAN技术1. 什么是WAN？WAN的主要特点是什么？2. PPP协议和HDLC协议分别是什么？请比较它们的异同。

3. 什么是Frame Relay？Frame Relay的工作原理及在WAN中的应用。

4. 请解释T1和E1的概念，以及它们在传输速率和应用方面的差异。

CCIE模拟考试题_思科认证考试.doc

CCIE模拟考试题_思科认证考试1.What statement is FALSE with respect to the operation of Unidirectional Link Detection?A. It negotiates the Unidirectional Link Detection link state during physical signaling.B. It performs tasks that autonegotiation cannot perform.C. It works by exchanging protocol packets between the neighboring devices.D. Both devices on the link must support Unidirectional Link Detection and have it enabled on respective ports.2.What is true concerning Traffic contract, Traffic shaping, and Traffic policing in ATM networks?A. They are parameters of PNNI set during PNNI configuration.B. They are forms of QoS features used in ATM networks.C. They are types of SVCs.D. They are types of PVCs.E. They are only used between ATM switches to control traffic flows.3.Which are the primary reasons to use traffic shaping? (Select two)A. To control the maximum rate of traffic transmitted or received on an interface.B. To control access to available bandwidth.C. To define Layer 3 aggregate or granular incoming or outgoing bandwidth rate limits.D. To control the average queue size by indicating to the end hosts when they should temporarily slow down transmission of packets.E. To ensure that traffic conforms to the policies established for it.4.In a bridged network running IEEE 802.1d spanning tree, what parameter will a bridge take form the root bridge?A. MaxageB. Forwarding delayC. Hello timeD. All of the above5.What statement is FALSE concerning the use of SPAN on the Catalyst 6500?A. It is possible to configure SPAN to have a Gigabit port, such as source port, and a 10/100 port as the destination port.B. If the source port is configured as a trunk port, the traffic on the destination port will be tagged as well, regardless of the configuration on the destination port.C. When a SPAN session is active the destination port does not participate in Spanning Tree.D. With SPAN an entire VLAN can be configured to be the source.E. In one SPAN session it is possible to monitor multiple ports that do not belong to the same VLAN.。

2023年CCNA考试真题

2023年CCNA考试真题2023年CCNA考试正式开考啦！本次考试涉及网络技术的基础知识，将对考生的技术水平进行全面考察。

下面是本次考试的真题，希望能够帮助考生更好地复习。

【第一部分：选择题】（共10题，每题2分，共计20分）1. OSI模型中，位于网络层的协议是：A. TCPB. IPC. HTTPD. UDP2. 下面哪个命令可以查看路由表信息：A. pingB. tracertC. ipconfigD. route print3. 在IP地址192.168.0.1/24中，/24表示什么意思：A. 子网掩码B. 路由器IP地址C. 网络IDD. 主机ID4. 下面哪个协议可以实现主机与交换机之间的通信：A. BGPB. ARPC. MPLSD. SNMP5. 下面哪个命令可以查看IP地址的连通性：A. telnetB. netstatC. pingD. tracert6. VLAN是指：A. 虚拟本地区域网络B. 可视化局域网C. 个人局域网D. 无线局域网7. 下面哪个设备可以实现不同局域网之间的互联：A. 集线器B. 路由器C. 交换机D. 网桥8. 下面哪个协议负责在网络中寻找设备的物理地址：A. ARPB. ICMPC. OSPFD. BGP9. 下面哪个命令可以查看交换机的端口信息：A. show ip interface briefB. show mac-address-tableC. show running-configD. show version10. 下面哪个协议可以实现安全的远程登录：A. FTPB. HTTPC. SSHD. Telnet【第二部分：填空题】（共5题，每题4分，共计20分）1. 在OSI模型中，位于物理层的设备是_________。

2. 在TCP/IP协议族中，位于传输层的协议是_________。

3. IP地址由_________位二进制数组成。

新10月CCNA题库word版1~100题共24页

QUESTION 1When you are logged into a switch, which prompt indicates that you are in privileged mode?A. %B. @C. >D. $E. #QUESTION 2Which command shows system hardware and software version information?A. show configurationB. show environmentC. show inventoryD. show platformE. show versionQUESTION 3Cisco Catalyst switches CAT1 and CAT2 have a connection between them using ports FA0/13. An 802. 1Qtrunk is configured between the two switches. On CAT1, VLAN 10 is chosen as native, but on CAT2 thenative VLAN is not specified.What will happen in this scenario?A. 802.1Q giants frames could saturate the link.B. VLAN 10 on CAT1 and VLAN 1 on CAT2 will send untagged frames.C. A native VLAN mismatch error message will appear.D. VLAN 10 on CAT1 and VLAN 1 on CAT2 will send tagged frames.QUESTION 4Which command would correctly configure a serial port on a router with the last usable host address in the192.216.32.32/29 subnet?A. Router(config-if)# ip address 192.216.32.38 255.255.255.240B. Router(config-if)# ip address 192.216.32.39 255.255.255.224C. Router(config-if)# ip address 192.216.32.63 255.255.255.248D. Router(config-if)# ip address 192.216.32.39 255.255.255.248E. Router(config-if)# ip address 192.216.32.63 255.255.255.248F. Router(config-if)# ip address 192.216.32.38 255.255.255.248QUESTION 5The network default gateway applying to a host by DHCP is 192.168.5.33/28. Which option is the valid IPaddress of this host?A. 192.168.5.55B. 192.168.5.47C. 192.168.5.40D. 192.168.5.32E. 192.168.5.14QUESTION 6Which two addresses can be assigned to a host with a subnet mask of 255.255.254.0? (Choose two.)A. 113.10.4.0B. 186.54.3.0C. 175.33.3.255D. 26.35.2.255E. 17.35.36.0QUESTION 7The network administrator has asked you to check the status of the workstation's IP stack by pinging theloopback address. Which address would you ping to perform this task?A. 10.1.1.1B. 127.0.0.1C. 192.168.0.1D. 239.1.1.1QUESTION 8Workstation A has been assigned an IP address of 192.0.2.24/28. Workstation B has been assigned an IPaddress of 192.0.2.100/28. The two workstations are connected with a straight-through cable. Attempts toping between the hosts are unsuccessful. What two things can be done to allow communications betweenthe hosts? (Choose two.)A. Replace the straight-through cable with a crossover cable.B. Change the subnet mask of the hosts to /25.C. Change the subnet mask of the hosts to /26.D. Change the address of Workstation A to 192.0.2.15.E. Change the address of Workstation B to 192.0.2.111.QUESTION 9Your ISP has given you the address 223.5.14.6/29 to assign to your router's interface. They have alsogiven you the default gateway address of 223.5.14.7. After you have configured the address, the router isunable to ping any remote devices. What is preventing the router from pinging remote devices?A. The default gateway is not an address on this subnet.B. The default gateway is the broadcast address for this subnet.C. The IP address is the broadcast address for this subnet.D. The IP address is an invalid class D multicast address.QUESTION 10Which command is used to copy the configuration from RAM into NVRAM?A. copy running-config startup-configB. copy startup-config: running-config:C. copy running config startup configD. copy startup config running configE. write terminalQUESTION 11Which command is used to load a configuration from a TFTP server and merge the configuration intoRAM?A. copy running-config: TFTP:B. copy TFTP: running-configC. copy TFTP: startup-configD. copy startup-config: TFTP:QUESTION 12A system administrator types the command to change the hostname of a router. Where on the Cisco IFS isthat change stored?A. NVRAMB. RAMC. FLASHD. ROME. PCMCIAQUESTION 13Which command is used to configure a default route?A. ip route 172.16.1.0 255.255.255.0 0.0.0.0B. ip route 172.16.1.0 255.255.255.0 172.16.2.1C. ip route 0.0.0.0 255.255.255.0 172.16.2.1D. ip route 0.0.0.0 0.0.0.0 172.16.2.1QUESTION 14If IP routing is enabled, which two commands set the gateway of last resort to the default gateway?(Choose two.)A. ip default-gateway 0.0.0.0B. ip route 172.16.2.1 0.0.0.0 0.0.0.0C. ip default-network 0.0.0.0D. ip default-route 0.0.0.0 0.0.0.0 172.16.2.1E. ip route 0.0.0.0 0.0.0.0 172.16.2.1QUESTION 15Which command would you configure globally on a Cisco router that would allow you to view directlyconnected Cisco devices?A. enable cdpB. cdp enableC. cdp runD. run cdpQUESTION 16Which command is used to see the path taken by packets across an IP network?A. show ip routeB. show routeC. tracerouteD. trace ip routeQUESTION 17Which command is used to debug a ping command?A. debug icmpB. debug ip icmpC. debug tcpD. debug packetQUESTION 18Which command displays CPU utilization?A. show protocolsB. show processC. show systemD. show versionQUESTION 19When configuring a serial interface on a router, what is the default encapsulation?A. atm-dxiB. frame-relayC. hdlcD. lapbE. pppQUESTION 20What must be set correctly when configuring a serial interface so that higher-level protocols calculate thebest route?A. bandwidthB. delayC. loadD. reliabilityQUESTION 21A company implements video conferencing over IP on their Ethernet LAN. The users notice that thenetwork slows down, and the video either stutters or fails completely. What is the most likely reason forthis?A. minimum cell rate (MCR)B. quality of service (QoS)C. modulationD. packet switching exchange (PSE)E. reliable transport protocol (RTP)QUESTION 22Which layer in the OSI reference model is responsible for determining the availability of the receivingprogram and checking to see if enough resources exist for that communication?A. transportB. networkC. presentationD. sessionE. applicationQUESTION 23Data transfer is slow between the source and destination. The quality of service requested by the transportlayer in the OSI reference model is not being maintained. To fix this issue, at which layer should thetroubleshooting process begin?A. presentationB. sessionC. transportD. networkE. physicalQUESTION 24Which protocols are found in the network layer of the OSI reference model and are responsible for pathdetermination and traffic switching?A. LANB. routingC. WAND. networkQUESTION 25Which command reveals the last method used to powercycle a router?A. show reloadB. show bootC. show running-configD. show versionQUESTION 26Which three options are valid WAN connectivity methods? (Choose three.)A. PPPB. WAPC. HDLCD. MPLSE. L2TPv3CCNA考试报名1700元7F. ATMQUESTION 27Refer to the exhibit. Which WAN protocol is being used?A. ATMB. HDLCC. Frame RelayD. PPPQUESTION 28What is the difference between a CSU/DSU and a modem?A. A CSU/DSU converts analog signals from a router to a leased line; a modem converts analog signalsfrom a router to a leased line.B. A CSU/DSU converts analog signals from a router to a phone line; a modem converts digital signalsfrom a router to a leased line.C. A CSU/DSU converts digital signals from a router to a phone line; a modem converts analog signalsfrom a router to a phone line.D. A CSU/DSU converts digital signals from a router to a leased line; a modem converts digital signalsfrom a router to a phone line.QUESTION 29A network administrator must configure 200 switch ports to accept traffic from only the currently attachedCCNA考试报名1700元8host devices. What would be the most efficient way to configure MAC-level security on all these ports?A. Visually verify the MAC addresses and then telnet to the switches to enter the switchport-port securitymac-address command.B. Have end users e-mail their MAC addresses. Telnet to the switch to enter the switchport-port securitymac-address command.C. Use the switchport port-security MAC address sticky command on all the switch ports that have enddevices connected to them.D. Use show mac-address-table to determine the addresses that are associated with each portand thenenter the commands on each switch for MAC address port-security.QUESTION 30When troubleshooting a Frame Relay connection, what is the first step when performing a loopback test?A. Set the encapsulation of the interface to HDLC.B. Place the CSU/DSU in local-loop mode.C. Enable local-loop mode on the DCE Frame Relay router.D. Verify that the encapsulation is set to Frame Relay.What occurs on a Frame Relay network when the CIR is exceeded?A. All TCP traffic is marked discard eligible.B. All UDP traffic is marked discard eligible and a BECN is sent.C. All TCP traffic is marked discard eligible and a BECN is sent.D. All traffic exceeding the CIR is marked discard eligible.QUESTION 32What are two characteristics of Frame Relay point-to-point subinterfaces? (Choose two.)A. They create split-horizon issues.B. They require a unique subnet within a routing domain.C. They emulate leased lines.D. They are ideal for full-mesh topologies.E. They require the use of NBMA options when using OSPF.QUESTION 33Refer to the exhibit. Addresses within the range 10.10.10.0/24 are not being translated to the 1.128.0/16range. Which command shows if 10.10.10.0/24 are allowed inside addresses?A. debug ip natB. show access-listC. show ip nat translationD. show ip nat statisticsQUESTION 34A wireless client cannot connect to an 802.11b/g BSS with a b/g wireless card. The client section of theaccess point does not list any active WLAN clients. What is a possible reason for this?A. The incorrect channel is configured on the client.B. The client's IP address is on the wrong subnet.C. The client has an incorrect pre-shared key.D. The SSID is configured incorrectly on the client.QUESTION 35Which two features did WPAv1 add to address the inherent weaknesses found in WEP? (Choose two.)CCNA考试报名1700元10艾迪飞论坛http://bbs.edify艾迪飞论坛http://bbs.edifyA. a stronger encryption algorithmB. key mixing using temporal keysC. shared key authenticationD. a shorter initialization vectorE. per frame sequence countersQUESTION 36Which two wireless encryption methods are based on the RC4 encryption algorithm? (Choose two.)A. WEPB. CCKMC. AESD. TKIPE. CCMPQUESTION 37What are two characteristics of RIPv2? (Choose two.)A. classful routing protocolB. variable-length subnet masksC. broadcast addressingD. manual route summarizationE. uses SPF algorithm to compute pathQUESTION 38Which two Ethernet fiber-optic modes support distances of greater than 550 meters?A. 1000BASE-CXCCNA考试报名1700元11艾迪飞论坛http://bbs.edify艾迪飞论坛http://bbs.edify艾迪飞论坛http://bbs.edifyB. 100BASE-FXC. 1000BASE-LXD. 1000BASE-SXE. 1000BASE-ZXQUESTION 39What two things will a router do when running a distance vector routing protocol? (Choose two.)A. Send periodic updates regardless of topology changes.B. Send entire routing table to all routers in the routing domain.C. Use the shortest-path algorithm to the determine best path.D. Update the routing table based on updates from their neighbors.E. Maintain the topology of the entire network in its database.QUESTION 40Refer to the exhibit. According to the routing table, where will the router send a packet destined for10.1.5.65?A. 10.1.1.2B. 10.1.2.2C. 10.1.3.3D. 10.1.4.4QUESTION 41Which command shows if an access list is assigned to an interface?A. show ip interface [interface] access-listsB. show ip access-lists interface [interface]C. show ip interface [interface]D. show ip access-lists [interface]QUESTION 42Refer to the exhibit. Which rule does the DHCP server use when there is an IP address conflict?A. The address is removed from the pool until the conflict is resolved.B. The address remains in the pool until the conflict is resolved.C. Only the IP detected by Gratuitous ARP is removed from the pool.D. Only the IP detected by Ping is removed from the pool.E. The IP will be shown, even after the conflict is resolved.QUESTION 43Refer to the exhibit. You are connected to the router as user Mike. Which command allows you to seeoutput from the OSPF debug command?A. terminal monitorB. show debuggingC. show sessionsD. show ip ospf interfaceQUESTION 44Refer to the exhibit. If number 2 is selected from the setup script, what happens when the user runs setupfrom a privileged prompt?A. Setup is additive and any changes will be added to the config script.B. Setup effectively starts the configuration over as if the router was booted for the first time.C. Setup will not run if an enable secret password exists on the router.D. Setup will not run, because it is only viable when no configuration exists on the router. QUESTION 45Refer to the exhibit. Which (config-router) command will allow the network represented on the interface tobe advertised by RIP?A. redistribute ethernet0B. network ethernet0CCNA考试报名1700元14艾迪飞论坛http://bbs.edify艾迪飞论坛http://bbs.edifyC. redistribute 10.12.0.0D. network 10.12.0.0QUESTION 46Refer to the exhibit. What information can be gathered from the output?A. One router is running RIPv1.B. RIP neighbor is 224.0.0.9.C. The network contains a loop.D. Network 10.10.1.0 is reachable.QUESTION 47Refer to the exhibit. What type of connection would be supported by the cable diagram shown?A. PC to routerB. PC to switchC. server to routerD. router to routerQUESTION 48Refer to the exhibit. What type of connection would be supported by the cable diagram shown?A. PC to routerB. PC to switchC. server to switchD. switch to routerQUESTION 49Which two statements describe the Cisco implementation of VLANs? (Choose two.)A. VLAN 1 is the default Ethernet VLAN.B. CDP advertisements are only sent on VLAN 1002.C. By default, the management VLAN is VLAN 1005.D. By default, the switch IP address is in VLAN 1005.E. VLAN 1002 through 1005 are automatically created and cannot be deleted.QUESTION 50Refer to the exhibit. What can be determined about the router from the console output?A. No configuration file was found in NVRAM.B. No configuration file was found in flash.C. No configuration file was found in the PCMCIA card.D. Configuration file is normal and will load in 15 seconds.QUESTION 52Refer to the exhibit. Which command would allow the translations to be created on the router?A. ip nat pool mynats 1.1.128.1 1.1.135.254 prefix-length 19B. ip nat outside mynats 1.1.128.1 1.1.135.254 prefix-length 19C. ip nat pool mynats 1.1.128.1 1.1.135.254 prefix-length 18D. ip nat outside mynats 1.1.128.1 1.1.135.254 prefix-length 18QUESTION 53Refer to the exhibit. An administrator pings the default gateway at 10.10.10.1 and sees the output asshown. At which OSI layer is the problem?A. data link layerB. application layerC. access layerD. session layerE. network layerQUESTION 54Refer to the exhibit. Which value will be configured for Default Gateway of the Local Area Connection?A. 10.0.0.0B. 10.0.0.254C. 192.223.129.0D. 192.223.129.254QUESTION 55Refer to the exhibit. The user at Workstation B reports that Server A cannot be reached. What is preventing Workstation B from reaching Server A?A. The IP address for Server A is a broadcast address.B. The IP address for Workstation B is a subnet address.C. The gateway for Workstation B is not on the same subnet.D. The gateway for Server A is not on the same subnet.QUESTION 56Refer to the exhibit. What does the (*) represent in the output?A. Packet is destined for a local interface to the router.B. Packet was translated, but no response was received from the distant device.C. Packet was not translated, because no additional ports are available.D. Packet was translated and fast switched to the destination.QUESTION 57Refer to the exhibit. What command sequence will enable PAT from the inside to outside network?A. (config) ip nat pool isp-net 1.2.4.2 netmask 255.255.255.0 overloadB. (config-if) ip nat outside overloadC. (config) ip nat inside source list 1 interface ethernet1 overloadD. (config-if) ip nat inside overloadQUESTION 58Refer to the exhibit. What will happen to HTTP traffic coming from the Internet that is destined for172.16.12.10 if the traffic is processed by this ACL?A. Traffic will be dropped per line 30 of the ACL.B. Traffic will be accepted per line 40 of the ACL.C. Traffic will be dropped, because of the implicit deny all at the end of the ACL.D. Traffic will be accepted, because the source address is not covered by the ACL.QUESTION 59Refer to the exhibit. Which statement describes the effect that the Router1 configuration has on devices inthe 172.16.16.0 subnet when they try to connect to SVR-A using Telnet or SSH?A. Devices will not be able to use Telnet or SSH.B. Devices will be able to use SSH, but not Telnet.C. Devices will be able to use Telnet, but not SSH.D. Devices will be able to use Telnet and SSH.QUESTION 60What are three advantages of VLANs? (Choose three.)A. VLANs establish broadcast domains in switched networks.B. VLANs utilize packet filtering to enhance network security.C. VLANs provide a method of conserving IP addresses in large networks.D. VLANs provide a low-latency internetworking alternative to routed networks.E. VLANs allow access to network services based on department, not physical location.F. VLANs can greatly simplify adding, moving, or changing hosts on the network.QUESTION 61An administrator would like to configure a switch over a virtual terminal connection from locations outsideof the local LAN. Which of the following are required in order for the switch to be configured from a remotelocation? (Choose two.)A. The switch must be configured with an IP address, subnet mask, and default gateway.B. The switch must be connected to a router over a VLAN trunk.C. The switch must be reachable through a port connected to its management VLAN.D. The switch console port must be connected to the Ethernet LAN.E. The switch management VLAN must be created and have a membership of at least one switch port.F. The switch must be fully configured as an SNMP agent.QUESTION 62Which of the following host addresses are members of networks that can be routed across the publicInternet? (Choose three.)A. 10.172.13.65B. 172.16.223.125C. 172.64.12.29D. 192.168.23.252E. 198.234.12.95F. 212.193.48.254QUESTION 63Given a subnet mask of 255.255.255.224, which of the following addresses can be assigned to networkhosts? (Choose three.)A. 15.234.118.63B. 92.11.178.93C. 134.178.18.56D. 192.168.16.87E. 201.45.116.159F. 217.63.12.192QUESTION 64Which of the following are benefits of VLANs? (Choose three.)A. They increase the size of collision domains.B. They allow logical grouping of users by function.C. They can enhance network security.D. They increase the size of broadcast domains while decreasing the number of collision domains.E. They increase the number of broadcast domains while decreasing the size of the broadcast domains.F. They simplify switch administration.Which router IOS commands can be used to troubleshoot LAN connectivity problems? (Choose three.)A. pingB. tracertC. ipconfigD. show ip routeE. winipcfgF. show interfacesQUESTION 67。

思科CCNA考试答案(全)

CCNA思科考试答案（全）第 1 章考试1一家拥有10 名员工的小型公司使用单个LAN 在计算机之间共享信息。

哪种类型连接适合此公司？由当地电话服务提供商提供的拨号连接能够使公司方便且安全地连接员工的虚拟专用网络通过当地服务提供商建立的私有专用线路通过当地服务提供商提供的宽带服务（如DSL）答案：4解析：对于这种小型办公室，比较适合通过被称为数字用户线路(DSL) 的常见宽带服务实现Internet 连接，这种服务由当地的电话服务提供商提供。

由于员工人数很少，带宽的问题并不突出。

如果公司较大，在远程站点有分支机构，则专用线路会更加适合。

如果公司员工需要通过Internet 与公司联系，则采用虚拟专用网。

2哪种网络情况需要使用WAN？员工工作站需要获取动态分配的IP 地址。

员工在出差时需要通过VPN 连接到公司电子邮件服务器。

分支机构的员工需要与同一园区网络上的另一座建筑物内的公司总部共享文件。

员工需要访问托管在其建筑物内DMZ 中的公司Web 服务器上的网页。

答案：2解析：当出差的员工需要通过WAN 连接到公司电子邮件服务器时，VPN 将通过WAN 连接在员工笔记本电脑与公司网络之间创建一个安全隧道。

通过DHCP 获取动态IP 地址是LAN 通信的功能。

在企业园区的不同建筑物之间共享文件可通过LAN 基础设施来实现。

DMZ 是企业LAN 基础设施内一个受保护的网络。

3以下哪项描述了WAN 的特征？WAN 和LAN 在同一地理范围内运行，但有串行链路。

WAN 网络归运营商所有。

所有串行链路均被视为WAN 连接。

WAN 可提供到园区主干网的终端用户网络连接。

答案：2解析：WAN 可用于将企业LAN 互连到远程分支机构站点LAN 和远程工作人员站点。

WAN 归运营商所有。

虽然WAN 连接一般通过串行接口实现，但并不是所有串行链路均连接至WAN。

LAN（而非WAN）可在组织中提供终端用户网络连接。

4电路交换WAN 技术的两个常见类型是什么？（请选择两项。

思科认证考试(CCNA)考试模拟题集锦(1-71题)及答案

思科认证考试（ＣＣＮＡ）考试模拟题集锦(1-71题)及答案19及答案1. [OxNx] During a TFTP transfer using Cisco Routers what is the numeric value, in decimal, of the destination port field of the User Datagram Protocol (UDP) header? a) 96b) 47c) a random number above 1024d) 69e) none of the above2. [CxNx] What is the standard encapsulation method used by Cisco routers for the Internet Protocol (IP) on it’s Ethernet interfaces?a) SNAPb) ARPAc) NOVELL-ETHERd) DARPAe) Ethernet_802.33. [CxNx] What will be the correct command on a Cisco router to set the IP address of an interface assuming you are at the "router(config-if)#" prompt?a) ip address 1.1.1.1 255.255.255.0b) ip address 1.1.1.1c) ip 1.1.1.1d) ip 1.1.1.1 255.255.255.0e) none of the above4. [CxNx] Which commands will display the IP addresses of all interfaces on a Cisco Router? (Choose all that apply)a) show ip routeb) show ip addressc) show ip interfaced) show interfacee) display ip addresses5. [CxNx] Which of the following commands will display the contents of the ARP cache of your Cisco router?a) show ip arp cacheb) show ip routec) show ip arpd) show arpe) there is no way to display the ARP cache6. [CxNx] Reverse Address Resolution Protocol (RARP) is the process:a) Where an I P host resolves it’s IP address by broadcasting it’s MAC address to the network and a BOOTP server assigns it an IP address.b) Where an IP host resolves it’s MAC address by broadcasting to the local network it’s IP address.c) Where an IP host tries to resolve the MAC address of a destination by sending a network broadcast. The destination responds to the broadcast with it’s MAC address.d) Where an IP host resolves a destination IP address by sending a broadcast on the local network and the destination host responds with it’s IP address.e)There is no such process.7. [OxNx] Which of the following applications requires the connection-oriented layer four protocol, TCP? (Choose all that apply)a) Telnetb) FTPc) TFTPd) SNMPe) none of the above8. [RxNx] Which of the following are link state Routing Protocols.(Choose all that apply.)a) IPb) OSPFc) RIPd) EIGRPe) IS-IS9. [CxNx] Of the following commands, identify the correct one for clearing the IP arp table in memory of the router.a) clear ip arp-cacheb) clear ip arp-tablec) clear arp-cached) clear arp-tablee) clear arp-ram10. [CxNx] Which of the following explains the correct definition of administrative distance as it pertains to Cisco’s IOS?a) The process by which routers select an administrator for an autonomous system.b) The process where a router will select the best path to a destination network.c) The process where a router will distance itself from other routers due to it’s lack of administrative experience.d) The process where a router will prioritize routing protocols so that in the event two routing protocols have conflicting next hop addresses, the routing protocol with the lowest administrative distance will take priority.e) The process where a router will prioritize routing protocols so that in the event two routing protocols have conflicting next hop addresses, the routing protocol with the highest administrative distance will take priority.11. [ExNx] Collisions occur whena) multiple packets are placed on a serial linkb) multiple stations listen for traffic and transmit at the same timec) when multiple tokens are on a ring simultaneouslyd) beaconing process takes place12. [RINx] How many subnets are possible with a Class C address and a subnet mask of 255.255.255.252?a) 32b) 30c) 60d) 62e) 413. [RxNx] What commands will list all protocols that are currently being routed? (Choose all that apply.)a) show ip protocolb) show protocolc) show rund) show starte) All of the above14. [xxNx] Which of the following are true of access lists?a) Access list should have at least one permit statement.b) The last configured line should always be a permit statement.c) Every access-list will implicitly deny all traffic.d) Access-lists are processed top down.e) All of the above.15. [xxNx] If the access-group command is configured on an interface and there is no access-list created which of the following is most correct?a) An error message will appear.b) The command will be executed and deny all traffic out.c) The command will be executed and permit all traffic out.d) The command will be executed and permit all traffic in and out.e) The command will be executed and deny all traffic in and out.16. [xxNx] What is the result of the command?" access-list 101 permit tcp any 172.16.0.0 0.0.255.255 established"a) telnet sessions will be permitted regardless of the source addressb) telnet sessions will be denied regardless of the source addressc) telnet sessions will be denied if initiated from any address other than 172.16.0.0 networkd) telnet sessions will be permitted to the 172.16.0.0 network onlye) telnet sessions will be denied to the 172.16.0.0 network only17. [xxNx] Which is generally true of the location of access-lists? (Choose all that apply.)a) Standard lists will most likely be placed close to the destination.b) Standard lists will most likely be placed close to the source.c) Extended lists will most likely be placed close to the destination.d) Extended lists will most likely be placed close to the source.e) It does not matter.18. [RxNx] Which of the following is most correct?a) IP is to TCP. as IPX is to SPX.b) RTMP is to Appletalk as IP RIP is to IP.c) NLSP is to IPX as OSPF is to IP.d) a is true.e) b is true.f) a & b are true.g) c is true.h) b & c are true.i) a, b and c are true.19. [ExNx] If Host A sends a packet to Host B over ethernet and Host B is not active:a) The packet will time out.b) The packet will be removed by Host A.c) The NVRAM of Host B will remove the packet.d) The packet will "die" when it reaches the terminator.e) The packet will be removed by the token monitor.Coding Key and InformationThe first character represents the category of question.A - ATMB - BridgingC - Cisco specificE - EthernetF - Frame relayH - HDLCI - FDDIN - ISDNO - OSI modelP - PPPR - RoutingS - SwitchingT - Token ringX - X.25x - Not applicableThe second character represents protocol.A - AppletalkB - Banyan VinesD - DecnetI - IPL - Dial on DemandN - NLSPO - OSPFX - IPXx - Not ApplicableThe third character represents the certification that the question will help you prepare for.N - CCNA Exam #640-407P - CCNPAdvanced Cisco Router Configuration (ACRC) Exam 640-403Cisco LAN Switch Configuration (CLSC) Exam #640-404Cisco Monitoring and Troubleshooting Dial-up Services Exam #640-405Cisco Internetworking Troubleshooting ( CIT) Exam #640-406D - CCDA & CCDPCisco Design Specialist Exam #9E0-004Cisco Internetwork Design#640-025We will reserve the fourth character for future use.As an example, when you come across a question coded "BXDx", it signifies a question that will help you gain the CCDA or CCDP certification.CCNA试题1-19答案1. [OxNx] During a TFTP transfer using Cisco Routers what is the numeric value, in decimal, of the destination port field of the User Datagram Protocol (UDP) header?a) 96b) 47c) a random number above 1024d) 69e) none of the aboveAnswerd) 69Here is a sampling of other port numbers and the application they are associated with. The first 8 of these protocols are automatically forwarded through the router by using the helper-address commandTrivial File Transfer (TFTP) (port 69)Domain Name System (port 53)IEN-116 Name Server (port 42)Time service (port 37)NetBIOS Name Server (port 137)NetBIOS Datagram Server (port 138)Boot Protocol (BootP) client and server datagrams (port 67)TACACS service (port 49)Simple Mail Transfer Protocol (25)File Transfer Protocol (21)Simple Network Management Protocol (161)2. [CxNx] What is the standard encapsulation method used by Cisco routers for the Internet Protocol (IP) on it’s Ethernet interfaces?a) SNAPb) ARPAc) NOVELL-ETHERd) DARPAe) Ethernet_802.3Answerb) ARPASNAP is the default encapsulation for a token ring interface NOVELL-ETHER is the default encapsulation for a ipx interface.3. [CxNx] What will be the correct command on a Cisco router to set the IP address of an interface assuming you are at the "router(config-if)#" prompt?a) ip address 1.1.1.1 255.255.255.0b) ip address 1.1.1.1c) ip 1.1.1.1d) ip 1.1.1.1 255.255.255.0e) none of the aboveAnswera) ip address 1.1.1.1 255.255.255.0If you are not in the configuration mode, the ip address can be set by using the setup mode.Configuring interface Ethernet0/0:Is this interface in use? [yes]:Configure IP on this interface? [yes]:IP address for this interface [10.10.10.1]: 10.10.10.1Number of bits in subnet field [16]: 16Class A network is 10.0.0.0, 16 subnet bits; mask is /24Take note when using the setup mode the mask is configured using the number of subnet bits.4. [CxNx] Which commands will display the IP addresses of all interfaces on a Cisco Router? (Choose all that apply)a) show ip routeb) show ip addressc) show ip interfaced) show interfacee) display ip addressesAnswerc) show ip interfaced) show interfaceExamples of each of these commands are shown below: Router_A#sh int e0/0Ethernet0/0 is up, line protocol is upHardware is AmdP2, address is0010.7b15.bd41(bia 0010.7b15.bd41)Internet address is 10.10.10.1/24MTU 1500 bytes, BW 10000 Kbit,DLY 1000 usec,rely 255/255, load 1/255Encapsulation ARPA, loopback not set,keepalive set (10 sec)ARP type: ARPA, ARP Timeout 04:00:00Last input never, output 00:00:06,output hang neverLast clearing of "show interface"counters neverQueueing strategy: fifoOutput queue 0/40, 0 drops;input queue 0/75,0 drops5 minute input rate 0 bits/sec,0 packets/sec5 minute output rate 0 bits/sec,0 packets/sec0 packets input, 0 bytes,0 no bufferReceived 0 broadcasts, 0 runts,0 giants,0 throttles, 0 input errors, 0 CRC,0 frame, 0 overrun, 0 ignored,0 abort0 input packets with dribblecondition detected127 packets output, 11802 bytes,0 underruns0 output errors, 0 collisions,2 interface resets0 babbles, 0 late collision,0 deferred0 lost carrier, 0 no carrier0 output buffer failures, 0 outputbuffers swapped outRouter_A#sh ip int e0/0Ethernet0/0 is up, line protocol is upInternet address is 10.10.10.1/24Broadcast address is 255.255.255.255Address determined bynon-volatile memoryMTU is 1500 bytesHelper address is not setDirected broadcast forwarding is enabledOutgoing access list is not setInbound access list is not setProxy ARP is enabledSecurity level is defaultSplit horizon is enabledICMP redirects are always sentICMP unreachables are always sentICMP mask replies are never sentIP fast switching is enabledIP fast switching on the sameinterface is disabledIP multicast fast switching is enabledRouter Discovery is disabledIP output packet accounting is disabledIP access violation accounting isdisabledTCP/IP header compression is disabledProbe proxy name replies are disabledGateway Discovery is disabledPolicy routing is disabledNetwork address translation is disabled5. [CxNx] Which of the following commands will display the contents of the ARP cache of your Cisco router?a) show ip arp cacheb) show ip routec) show ip arpd) show arpe) there is no way to display the ARP cacheAnswerc) show ip arpExample:Router_A#sh ip arpProtocol Address Age(min) Hardware Address Type InterfaceInternet 1.1.1.2 - 0010.7b15.bd50 ARPA FastEthernet1/0Internet 10.10.10.1 - 0010.7b15.bd41 ARPA Ethernet0/06. [CxNx] Reverse Address Resolution Protocol (RARP) is the process:a) Where an IP host resolves it’s IP address by broadcasting it’s MAC address to the network a nd a BOOTP server assigns it an IP address.b) Where an IP host resolves it’s MAC address by broadcasting to the local network it’s IP address.c) Where an IP host tries to resolve the MAC address of a destination by sending a network broadcast. The dest ination responds to the broadcast with it’s MAC address.d) Where an IP host resolves a destination IP address by sending a broadcast on the local network and the destination host responds with it’s IP address.e)There is no such process.Answera) Whe re an IP host resolves it’s IP address by broadcasting it’s MAC address to the network and a BOOTP server assigns it an IP address.Choice C describes Address Resolution Protocol (ARP). A host never has to resolve it’s own MAC address. The MAC address is burned into the Network Interface card. When the host is booted the MAC address will be loaded into memory.7. [OxNx] Which of the following applications requires the connection-oriented layer four protocol, TCP? (Choose all that apply)a) Telnetb) FTPc) TFTPd) SNMPe) none of the aboveAnswera) Telnetb) FTPTFTP and SNMP use layer 4 UDP.8. [RxNx] Which of the following are link state Routing Protocols.(Choose all that apply.)a) IPb) OSPFc) RIPd) EIGRPe) IS-ISAnswerb) OSPFe) IS-ISA link state routing protocol advertises, to it’s neighbors, the state of the link when the state of the link changes.A distance vector routing protocol advertises its routing table periodically.9. [CxNx] Of the following commands, identify the correct one for clearing the IP arp table in memory of the router.a) clear ip arp-cacheb) clear ip arp-tablec) clear arp-cached) clear arp-tablee) clear arp-ramAnswerc) clear arp-cacheIf you have changed an ip address or a NIC card on a host you might use this command to reset the cache.10. [CxNx] Which of the following explains the correct definition of administrative distance as it pertains to Cisco’s IOS?a) The process by which routers select an administrator for an autonomous system.b) The process where a router will select the best path to a destination network.c) The process where a router will distance itself from other routers due to it’s lack of administrative experience.d) The process where a router will prioritize routing protocols so that in the event two routing protocols have conflicting next hop addresses, the routing protocol with the lowest administrative distance will take priority.e) The process where a router will prioritize routing protocols so that in the event two routing protocols have conflicting next hop addresses, the routing protocol with the highest administrative distance will take priority.Answerd) The process where a router will prioritize routing protocols so that in the event two routing protocols have conflicting next hop addresses, the routing protocol with the lowest administrative distance will take priority.Cisco uses administrative distances (AD) to measure the reliability of the routing protocol. The lower the (AD) the more reliable the protocol.Router_C#sh ip routeCodes: C - connected, S - static,I - IGRP, R - RIP,M - mobile, B - BGPD - EIGRP, EX - EIGRP external, O - OSPF,IA - OSPF inter areaN1 - OSPF NSSA external type 1, N2 - OSPFNSSA external type 2E1 - OSPF external type 1,E2 - OSPF external type 2,E - EGPi - IS-IS, L1 - IS-IS level-1,L2 - IS-IS level-2, * -candidate defaultU - per-user static route, o - ODRGateway of last resort is not set172.16.0.0/24 is subnetted, 2 subnetsC 172.16.1.0 is directly connected,Serial1C 172.16.2.0 is directly connected,Serial0I 10.0.0.0/8 [100/8576] via 172.16.1.1,00:00:09, Serial1[100/8576] via 172.16.2.1, 00:00:19,Serial0The 100 in bold is the administrativedistance for IGRP.A partial list of administrative distances is included below:Protocol ADEIGRP 90IGRP 100OSPF 110RIP 120BGP 180If a router hears a IP RIP and a IGRP update for the same network the router will discard the rip information. IP RIP uses hop count as it’s metric, while IGRP uses a composite metric including bandwidth and load, speed is the primary consideration.11. [ExNx] Collisions occur whena) multiple packets are placed on a serial linkb) multiple stations listen for traffic and transmit at the same timec) when multiple tokens are on a ring simultaneouslyd) beaconing process takes placeAnswerb) multiple stations listen for traffic and transmit at the same timeCollisions is a term that is used in an ethernet environment. Ethernet can be described as a listen then transmit scenario. First a station will listen for traffic if no traffic is sensed then a transmission will take place. If two stations transmit at the same time collisions will occur. The first station to detect the collision sends out a jamming signal to alert all stations a collision has occurred. At this point these stations set up a random interval timer when the timer expires re-transmission will occur.Token ring is a token passing process a station can transmit only when he has the token. There never can be multiple tokens on the ring. Early token release allows up to two data frames to be transmitted on a token ring LAN at the same time. Collisions do not occur on a token ring.Because of the point to point nature of serial links collisions do not occur.Beaconing is a term used in a token passing environment.12. [RINx] How many subnets are possible with a Class C address and a subnet mask of 255.255.255.252?a) 32b) 30c) 60d) 62e) 4Answerd) 62The above mask is using 6 bits to describe subnets. The formula used to determine the number of subnets (not including the all 0’s or all 1’s subnet) is 2n - 2 were n is the number of subnet bits. This is the number to use when configuring a ip address with the setup dialog.13. [RxNx] What commands will list all protocols that are currently being routed? (Choose all that apply.)a) show ip protocolb) show protocolc) show rund) show starte) All of the aboveAnswerb) show protocolc) show runShow ip protocol will show just the ip routing protocols that are currently configured. Show start may or may not show the current routed protocols.Below is the output of show protocolRouter_B#show protocolGlobal values:Internet Protocol routing is enabledAppletalk routing is enabledBRI0 is administratively down, line protocol is downBRI0:1 is administratively down, line protocol is downBRI0:2 is administratively down, line protocol is downSerial0 is administratively down, line protocol is downSerial1 is administratively down, line protocol is downSerial2 is administratively down, line protocol is downSerial3 is administratively down, line protocol is downTokenRing0 is administratively down, line protocol is down14. [xxNx] Which of the following are true of access lists?a) Access list should have at least one permit statement.b) The last configured line should always be a permit statement.c) Every access-list will implicitly deny all traffic.d) Access-lists are processed top down.e) All of the above.Answere) All of the above.Every access list has an implicit deny all at the end. What would the need be to create a access list with just deny statements. Access-list are processed from the top down therefore the order of each statement could be critical, for instance suppose you created an access list and the first line was a permit any and the next line was a deny. Since it’s top down processing a packet would be permitted to pass on the first line and the second line would never be executed. An extended list will give you a "match count" that will help in determining what the most efficient order should be.15. [xxNx] If the access-group command is configured on an interface and there is no access-list created which of the following is most correct?a) An error message will appear.b) The command will be executed and deny all traffic out.c) The command will be executed and permit all traffic out.d) The command will be executed and permit all traffic in and out.e) The command will be executed and deny all traffic in and out.d) The command will be executed and permit all traffic in and out.There are two steps to use an access list .1. Create the list2. Place the access list on a interfaceThe analogy I use in class is:Suppose you reside in a gated community. The community is not protected until you hire the guard and then place him at the gate. If you hire the guard and never place him at the gate all traffic will be permitted. When there is no access list on an interface it is implicit permit anyWhen an access list is placed on a interface it is implicit deny any16. [xxNx] What is the result of the command?" access-list 101 permit tcp any 172.16.0.0 0.0.255.255 established"a) telnet sessions will be permitted regardless of the source addressb) telnet sessions will be denied regardless of the source addressc) telnet sessions will be denied if initiated from any address other than 172.16.0.0 networkd) telnet sessions will be permitted to the 172.16.0.0 network onlye) telnet sessions will be denied to the 172.16.0.0 network onlyAnswerc) telnet sessions will be denied if initiated from any address other than 172.16.0.0 networkThe secret to this question is the key word "established." Established means that the packet will be permitted unless it is the first part of the three way handshake. Recall that when we initiate a TCP connection we have no ACK. How can we acknowledge a sequence number from the other side when we have not established a session with him?17. [xxNx] Which is generally true of the location of access-lists? (Choose all that apply.)a) Standard lists will most likely be placed close to the destination.b) Standard lists will most likely be placed close to the source.c) Extended lists will most likely be placed close to the destination.d) Extended lists will most likely be placed close to the source.e) It does not matter.Answera) Standard lists will most likely be placed close to the destination.d) Extended lists will most likely be placed close to the source.A standard list will only check the source address. It makes no difference where the packet is going. If you place a standard list close to the source you could very well be denying that traffic to go to other destinations. An extended list can be placed close to the source because we can permit or deny traffic based upon the source and destination address. This insures that only traffic we wish to have denied is denied.18. [RxNx] Which of the following is most correct?a) IP is to TCP. as IPX is to SPX.b) RTMP is to Appletalk as IP RIP is to IP.c) NLSP is to IPX as OSPF is to IP.d) a is true.e) b is true.f) a & b are true.g) c is true.h) b & c are true.i) a, b and c are true.i) a, b and c are true.19. [ExNx] If Host A sends a packet to Host B over ethernet and Host B is not active:a) The packet will time out.b) The packet will be removed by Host A.c) The NVRAM of Host B will remove the packet.d) The packet will "die" when it reaches the terminator.e) The packet will be removed by the token monitor.Answerd) The packet will "die" when it reaches the terminator.２０—３９及答案20. [TxNx] If Host A sends a packet to Host B over token ring, and Host B is not active: a) The packet will time out.b) The packet will be removed by Host A.c) The NVRAM of Host B will remove the packet.d) The packet will "die" when it reaches the terminator.e) The packet will be removed by the token monitor.21. [TxNx] If Host A sends a packet to Host B over token ring: Host A dies after transmitting, and Host B is not active:a) The packet will time out.b) The packet will be removed by Host A.c) The NVRAM of Host B will remove the packet.d) The packet will "die" when it reaches the terminator.e) The packet will be removed by the Active monitor.22. [FxNx] BECN and FECN are:a) Used to provide keepalives in a Frame Relay environmentb) Used to provide error checking in a Frame Relay environmentc) Used to provide congestion information in a Frame Relay environmentd) Used to provide flow control parameters in a Frame Relay environmente) BECN and FECN are not used in a Frame Relay environment.23. [RxNx] Which of the following are benefits of a Link-State routing protocol? (Choose all that apply.)a) Allows the use of a more robust addressing scheme.b) Allows for a larger scalable networkc) Reduces convergence timed) Allows "supernetting"e) All of the above.24. [OxNx] Which of the following are reasons for the OSI model?a) Standardizes interfacesb) Allows modular engineeringc) Facilitates learning and teachingd) All of the above.25. [RxNx] Which of the following is NOT a ROUTING protocol:a) OSPFb) RIPc) IPXd) EIGRP26. [RxNx] Which statement is NOT true about link state protocols:a) Link state advertisements are sent to all routers in an area.b) Each router executes the SPF algorithm.c) Link state routers keep a topological database of the network.d) Link state routers include the originating router s routing table.e) Link state routers know of possible alternate paths to a particular network.27. [RxNx] Which of the following would NOT appear in a routing table?a) Next hop addressb) Interface Port referencesc) MAC addressd) Network addresse) Metrics28. [OxNx] Which statement is true of the Datalink OSI layer ?a) 802.3 is the MAC sub layer.b) No such thingc) MAC sublayer provides the connection to the network layer.d) MAC sublayer uses SAPS to access the network layer.e) SAP sublayer uses the MAC layer to access the LAN medium.29. [RINx] Given the IP address of 193.243.12.43 and a subnet mask of 255.255.255.128, what is the subnet address?a) 194.243.12.32b) 193.243.0.0c) 194.243.12.43d) 193.243.12.128e) None of the above.30. [CxNx] Cisco uses a naming convention to identify frame types. Which four of the following mappings are correct?Cisco_name = Common_namea) cisco_II = Ethernet_IIb) arpa = Ethernet_IIc) sap = Ethernet_802.3d) sap = Ethernet_802.2 LLCe) Novell Ether = Ethernet_802.2 LLCf) cisco_802 = Ethernet_802.2 LLCg) snap = Token Ring Snaph) snap = Ethernet_SNAP31. [RxNx] In order to communicate throughout an internetwork, which of the following are required. Choose Two.a) The use of a routable protocol such as NetBEUI or LATb) A hierarchical naming scheme server such as DNSc) A host file at each communicating deviced) A two part network addressing scheme such as Network/Hoste) The use of a routable protocol such as IP or IPXf) The use of a routable protocol such as TCP or IPX32. [CxNx] What is the default route on an IP network? Choose one.a) This is the route that will be chosen first by IP for delivery of a datagram.。

CCNA考试题

CCNA考试题一、选择题（每题5分）1、具有第 3 层功能的以太网交换机有哪两项关键功能？（选择两项。

）（）A、第 3 层路由功能B、网络地址转换(NA T)C、与远程网络和设备建立远程访问连接D、广播流量管理和组播流量管理E、采用边界网关协议(BGP) 进行自治系统(AS) 间路由2、第 2 层以太网交换机有哪三项功能？（选择三项。

）（）A、防止广播B、增大每名用户可用的带宽C、减小冲突域的大小D、在网段间隔离流量E、在不同的网络间路由流量F、减少广播域的数量3、分层网络设计模型中的哪一层称为互连网络的高速主干层，其中高可用性和冗余性是该层的关键？（）A、接入层B、分布层C、网络层D、核心层E、工作组层F、 W AN 层4、分层网络设计模型中的哪一层提供了将设备接入网络的途径并控制允许那些设备通过网络进行通信？（）A、应用层B、接入层C、分布层D、网络层E、核心层5、在处于不同的VLAN 中的设备间配置通信需要使用OSI 模型中的哪个层？（）A、第 1 层B、第 3 层C、第 4 层D、第 5 层6、推荐同时在核心层和分布层采用哪种分层设计特征以在发生路由故障时保护网络？（）A、交换B、冗余C、聚合D、访问列表7、为支持客户端关联过程，802.11 标准中指定了哪两种身份验证方法？（选择两项。

）（）A、轻型可扩展身份验证协议(EAP)B、共享密钥C、高级加密标准(AES)D、临时密钥完整性协议(TKIP)E、开放式身份验证8、传统路由与单臂路由器有何区别？（）A、传统路由只能使用单个交换机接口。

单臂路由器可使用多个交换机接口。

（）B、单臂路由器使用子接口将多个逻辑网络连接到单个路由器端口。

传统路由在每个逻辑网络中使用一个端口。

C、传统路由使用路由协议来向其它路由器更新路由。

单臂路由器仅将数据路由到直连网络。

D、单臂路由器不提供多个连接，因此消除了使用STP的需要。

传统路由使用通向路由器的多条路径，因此需要STP。

CCNA考试自测题第1卷(一)

1) Match the following application layer services to their corresponding transport layerprotocol port. (匹配下列的应用层服务和它们对应的传输层协议端口)：A. SMTP 1. TCP/23B. FTP 2. TCP/25C. TFTP 3. TCP/80D. Te l n e t 4. TCP/21E. HTTP 5. UDP/69F. DNS 6. TCP/532) Which OSI reference model layer does Telnet function at (Te l n e t在哪一个O S I参考模型层运作)？A. Transport 下载B. NetworkC. SessionD. Application3) How many layers does the TCP/IP protocol suite have, compared to the OSI referencemodel (和O S I参考模型相比，T C P / I P协议具有几层)？A. TCP model has 4, OSI model has 6B. TCP model has 7, OSI model has 8C. TCP model has 4, OSI model has 7D. TCP model has 7, OSI model has 44) The TCP/IP protocol suite has a formal session layer that includes N etBIOS、RPCs andTLI functions (TCP/IP协议套件具有包含N e t B I O S、R P C和T L I功能的一个正式的会话层)。

A. TrueB. False5) What is the function of RPCs (RPC的功能是什么)？A. To move files from remote PCs to a local PCB. To make remote function calls transparent, so they appear to be loca lC. To initialize a program on a remote PCD. To send a procedure that is local to a remote node for processing elsewhere6) What does RPC stand for (RPC代表什么)？A. Remote personal computerB. Reserved-programming callC. Routed-procedure callD. Remote-procedure call7) What OSI reference model layer do sockets function at (套接字在O S I参考模型的哪层运作)？A. ApplicationB. PresentationC. SessionD. TransportE. NetworkF. Data linkG. Physical8) What function do sockets perform (套接字的功能是什么)？A. They make remote functions appear local, transparent to the userB. They transfer files to and from remote nodesC. They make the transport layer independentD. They allow multiple applications to share the same connection to the network9) What is WinSock (什么是Wi n S o c k )？A. A version of sockets for the Microsoft Windows platformB. Sockets on BSD UNIXC. A session layer API commonly considered to be its own protocolD. A network layer service for Microsoft Wi n d o w s10) What does TLI do (TLI的作用是什么)？A. It makes remote functions appear local, transparent to the userB. It transfers files to and from remote nodesC. It makes the transport layer independentD. It allows multiple applications to share the same connection to the network11) What OSI layer does NetBIOS function at (NetBIOS在O S I哪一层运作)？A. ApplicationB. PresentationC. SessionD. TransportE. NetworkF. Data LinkG. Physical12) Which protocols can NetBIOS bind to? (Select all that are applicable .) (NETBIOS可以绑定在哪个协议上，选择所有可能的协议)？A. AppletalkB. IPXC. IPD. NetBEUI13) What layers do not exist in the TCP/IP model that are in the OSI model (哪层不在T C P / I P模型中，但它在O S I模型中)？A. Application, presentation, and networkB. Presentation, session, and data linkC. Session, network, and physicalD. Presentation, data link, and physical14) What is a socket in the transport layer (传输层中的套接字是什么)？A. The socket is an IP address plus a portB. An API that makes the transport layer independentC. An API that allows multiple applications to share a network connectio nD. A function that makes remote procedures appear to be local15) What is a port (什么是端口)？A. An API that makes the transport layer independentB. An API that allows multiple applications to share a network connectio nC. A function that makes remote procedures appear to be localD. The point where upper-layer processes access transport layer services16) Which of the following services uses a process called windowing (下面的哪一个服务使用了所谓的窗口机制)？A. Reliable data transferB. Connection-oriented virtual circuitC. Buffered transferD. ResequencingE. MultiplexingF. Efficient, full-duplex transmissionG. Flow control17) What is UDP (什么是U D P )？A. An API that makes the transport layer independentB. A connectionless, unreliable transport protocolC. An API that allows multiple applications to share a network connectio nD. A function that makes remote procedures appear to be local18) What is IP (什么是I P )？A. It is the transport mechanism for upper layer servicesB. It is the session layer API for making the transport layer independe ntC. It is the network layer protocol that moves data from one node to anotherD. It is the physical layer protocol for Internet connections19) What is ICMP (什么是I C M P )？A. It is a network layer protocol that handles control messagesB. It is a network layer protocol that resolves addressesC. It is a session layer API that makes remote procedures transparent t o a userD. It is a transport layer function for unreliable transport20) Ping sends an ICMP echo command to an IP address in order to dete rmine whether anetwork connection exists to that node (Ping向一个I P地址发送了一个I C M P回送命令，目的是确定是否存在到那个节点的网络连接)？A. TrueB. False21) Which of the following best describes TCP/IP (下面的哪句话最准确地说明了T C P / I P )？A. A static protocolB. A proprietary protocolC. A collection of internetworking protocols22) UDP and TCP represent mechanisms used by which layer of the TCP/IP (UDP和T C P表示了T C P / I P的哪层使用的机制)？A. Data link layerB. Physical layerC. Presentation layerD. Transport layer23) RPCs provide which of the following (RPC提供了下面的哪个功能)？A. Connection-oriented sessionB. Transparency to make remote calls look localC. Portability of applications between heterogeneous systemsD. A and C onlyE. B and C onlyF. A, B, and C24) Distributed Computing Environment (DCE) is an example of (分布式计算环境( D E C )是下面的哪一项的一个例子)？A. OSI modelB. RPC implementationC. Extreme Data RepresentationD. A and B25) Which statement is true of WinSock (下面对Wi n S o c k的哪一句陈述是正确的)？A. It is a MAC applicationB. It represents a graphical user interfaceC. It represents a network layerD. It provides the means for sharing an Internet connection between mult iple IP protocolsuite utilities26) Which statement is true of TLI (下面关于T L I的哪一句陈述是正确的)？A. It is a layer in the OSI modelB. It is a layer in the TCP/IP modelC. It is a System V APID. It is part of the UNIX Kernel27) Which statement is true of Windows Name Server (WINS) (下面对于Windows 命名服务器( W I N S )的陈述中，哪一句是正确的)？A. It is a protocolB. It provides capability for name resolutionC. It is a network layerD. It is a proprietary name serverE. A, B, and D onlyF. B and D only28) ICMP、I P、ARP and RARP of the IP protocol suite map to (IP协议套件的I C M P、I P、A R P和R A R P映射到)：A. OSI layers 1 and 2B. OSI layer 5C. OSI layer 3D. OSI layer 229) Which layer is most important in providing reliable data exchange be tween two systems(在两个系统之间提供可靠的数据交换中，哪一层是最重要的)？A. Physical layerB. Data link layerC. Session layerD. Transport layer30) Which of the following does TCP provide (TCP提供了下面的哪一个功能)？A. Unreliable data streamB. Connectionless virtual circuitC. Flow controlD. Structured byte stream movement31) Of the following, which field is not a part of the TCP header (在下面各项中，哪一个字段不是T C P报头的一部分)？A. Subnet maskB. Sequence numberC. Data offsetD. Destination port32) What is the sequence number in a TCP header used for (在T C P报头中的顺序号的作用是什么)？A. AcknowledgmentsB. Reordering of the octets receivedC. Rejecting duplicate octets33) Variable sliding windows provide an explicit mechanism for notifying TCP if an intermediate node (for example, a router) becomes congested (在中间节点，例如一个路由器拥塞的情况下，可变滑动窗口提供了通知T C P的显式机制)。

ccna试题

ccna试题一、单选题1. 下面哪个是OSI模型的物理层？A. TCPB. IPC. EthernetD. HTTP答案：C2. 以下哪个是IPv6的全球未经分配地址？A. FC00::/7B. 2000::/3C. 8000::/4D. FFFF::/8答案：A3. 以下哪个在OSI模型的会话层工作？A. HTTPB. IPC. TCPD. NetBIOS答案：D二、多选题4. 下面哪些是用于路由器接口配置的命令？（选择两个）A. ip addressB. mac addressC. interfaceD. enable答案：A, C5. 下面哪些是IP协议的特点？（选择三个）A. 可靠传输B. 无连接C. 不可靠传输D. 面向连接答案：B, C, D6. 下面哪些是TCP的特点？（选择三个）A. 面向连接B. 可靠传输C. 无连接D. 面向字节流答案：A, B, D三、填空题7. TCP/IP协议族中，网络接口层对应的是__________。

答案：网络接口8. 在IPv6地址中，一个冒号表示__________。

答案：前缀和后缀之间的分隔符9. 在TCP连接终止过程中，主动关闭连接的一方发送的最后一个ACK分组中ACK标志位的值是__________。

答案：1四、解答题10. 请简要解释TCP/IP协议族中IP协议的作用。

答案：IP（Internet Protocol）协议是TCP/IP协议族中的一种网络层协议，主要负责在网络之间传输数据包。

它使用IP地址来标识网络上的设备，并通过路由选择算法实现数据包的正确传递。

IP协议是一种无连接的协议，不提供数据包的可靠传输，也不保证数据包按顺序到达目的地。

它使用IP头部来存储必要的控制信息，如源IP地址、目的IP地址、数据包长度等。

11. 请简要描述TCP三次握手的过程。

答案：TCP三次握手用于建立一个TCP连接。

过程如下：1. 客户端向服务器发送一个SYN（同步）分组，其中设置SYN标志位为1，并选择一个初始序列号。

CCNA认证考试真题

为⼤家收集整理了《CCNA认证考试真题》供⼤家参考，希望对⼤家有所帮助（1）TCP/IP Addressing and Protocol1: Your junior network administrator wants to know what the default subnet mask is for a Class C IP address. What do you tell him?A. 255.0.0.0B. 255.255.0.0C. 255.245.255.0D. 255.255.255.0E. 255.255.255.255 2: An application needs to have reliable, end-to-end connect-ivity. Which of the following protocols will give you reliable connectivity?A. TCPB. UDPC. IPD. ICMP 3: You are designing a network, which needs to support 55 users. You don't plan to extend the segment beyond the current number of users. Which subnet mask would best meet your needs?A. 255.255.0.0B. 255.255.255.0C. 255.255.255.192D. 255.255.255.160 4: You have added a new switch to your network. You want to manage it remotely, so you need to assign it an IP address. Your router that connects to the switch has an IP address of 172.16.12.33/27. Which of the following addresses can you assign to this switch?A. 172.16.12.33/28B. 172.16.12.32/27C. 172.16.12.33/27D. 172.16.12.34/27E. 172.16.12.35/28F. 172.16.12.38/28G. 172.16.12.63/27 5: The address 172.16.208.16/20 is a host address in which of the following subnets? A. 172.16.176.0–255.255.240.0B. 172.16.192.0–255.255.240.0C. 172.16.208.0–255.255.240.0D. 172.16.224.0–255.255.240.0 6: You are designing an IP address scheme for your brand new remote office. The vice president of IT calls to tell you that you will be in charge of the 192.168.1.64/26 subnetwork. This supplies you with a single subnetwork with 62 hosts. You need to have at least two subnets with 14 hosts in each subnet. What custom subnet mask should you use?A. 255.255.255.128B. 255.255.255.192C. 255.255.255.224D. 255.255.255.240E. 255.255.255.248 7: You have subnetted the 210.106.14.0 network with a /24 mask. Your boss at Acme, Inc. wants to know how many usable subnetworks and usable host addresses per subnet this would provide. What should you tell her?A. One network with 254 hostsB. Two networks with 128 hostsC. Four networks with 64 hostsD. Six networks with 30 hosts 8: Identify three valid host addresses in any subnet of the 201.168.27.0 network, assuming a fixed subnet mask of 255.255.255.240. (Choose three.)A. 201.168.27.33B. 201.168.27.112C. 201.168.27.119D. 201.168.27.126E. 201.168.27.175F. 201.168.27.208 9: What is the subnetwork address for a host with the IP address 201.100.5.68/28?A. 201.100.5.0B. 201.100.5.32C. 201.100.5.64D. 201.100.5.65E. 201.100.5.31F. 201.100.5.1 10: Which of the following protocols uses a three-way handshake mechanism to establish sessions?A. TCPB. IPC. UDPD. IPXE. Frame relay 11: Which of the following protocols is connection-oriented? A. TCPB. IPC. IPXD. Frame relay 12: You are using an application on your Windows 2000 client machines that provides error correction. You need a protocol to provide fast transport. Which protocol should your application use?A. TCPB. IPC. UDPD. SPXE. AppleTalk 13: When using TCP, after a session is open, the applications can adjust the number of segments they receive before sending an acknowledgment. This behavior is known as ______________.A. MTU adjustmentB. WindowingC. Flexible Send PathD. FCS 14: If the destination did not receive a segment, how will the TCP host know to resend the information?A. The ACK received will not include the segment number that was not received.B. The ACK received will include the segment number that was not received.C. The sending host will send a PACK to verify segment receipt.D. The destination host will send a YACK message back to the sending host. 15: You are planning on using a single network that supports 208 users. Which IP address class would you choose to be the most efficient?A. Class AB. Class BC. Class CD. Class DE. Class E 16: RFC 1918 defines the private IP address ranges. Which of the following IP addresses are considered part of these ranges? (Choose three.)A. 10.23.45.67B. 126.21.34.56C. 172.16.32.1D. 172.31.234.55E. 192.169.4.5 17: A new network is being designed for your company, Acme, Inc. If you use a Class C IP network, which subnet mask will provide one usable subnet per department while allowing enough usable host addresses for each department specified in the table?Department Number of Users Corporate 7 Customer Support 15 Financial 13 HR 7 Engineering 16 A. 255.255.255.0B. 255.255.255.192C. 255.255.255.224D. 255.255.255.240E. 255.255.255.248 18: Which of these protocols provides data transport, relying on the error correction capabilities of the application itself?A. UDPB. TCPC. SNMPD. ICMP 19: Which of the following are used by TCP to ensure reliable delivery of data? (Choose two.)A. MAC address resolutionB. Sequence numbersC. AcknowledgmentsD. PingE. Routing updates 20: You discover that you are able to adjust the window size of the TCP segment. You increase the window size to test the results. What will you observe happening on your network?A. Increased throughputB. Decreased throughputC. Increased latencyD. Decreased reliability21: Your organization is using the 192.168.1.0/24 address space. You need 28 subnets. What subnet mask would you use to create these subnets?A. 255.255.255.0B. 255.255.255.128C. 255.255.255.192D. 255.255.255.224E. 255.255.255.240F. 255.255.255.248 22: Which of the following protocols maps IP addresses to MAC addresses for connectivity to occur between two hosts?A. ARPB. RARPC. SLARPD. DHCP 23: Your junior network administrator cannot seem to ping a host in another network and asks you why it isn't working. Which of the following is not an answer that you would give him?A. The host's default gateway is down.B. The destination host is not powered on.C. The IP address of the router interface is incorrect.D. The IP address of the switch to which the destination host connects is incorrect.E. The host is in a different subnet. 24: Which of the following classes of IP addresses is utilized for multicasting?A. Class AB. Class BC. Class CD. Class D 25: You give your IT department a spreadsheet of IP addresses and their subnets. You receive a call from one of the junior techs asking what the /26 means next to the IP addresses. You tell her: A. It represents the number of hosts possible on that subnetwork.B. It represents the number of subnetworks that are being used.C. It represents the class of IP address being used.D. It represents the number of bits in the subnet mask that are 1. 26: You are given an IP network of 192.168.5.0 and told that you need to separate this network into subnetworks that can support a maximum of 16 hosts per subnet. This will help alleviate congestion on the network. What subnet mask can you use to create the subnets necessary to meet the given criteria?A. 255.0.0.0B. 255.255.0.0C. 255.255.255.0D. 255.255.255.224E. 255.255.255.240 27: Which of the following would a Class A network be assigned to?A. Government agencyB. Small-to-medium sized corporationD. An individual 28: A client has the IP address 192.168.5.98/27. Which of the following addresses are on the same subnet as this host? (Choose two.)A. 192.168.5.95B. 192.168.5.100C. 192.168.5.128D. 192.168.5.110 29: Which of the following IP addresses is not a public IP address that can be routed over the Internet?A. 2.3.4.5B. 11.12.13.14C. 165.23.224.2D. 172.31.45.34E. 203.33.45.22 30: You are given a Class B network. What is the default subnet mask assigned to the Class B network?A. 255.255.255.255B. 255.255.0.0C. 255.224.0.0D. 0.0.0.0 31: You are troubleshooting your router's interfaces. For some reason, the Ethernet interface will not accept the IP address of 192.168.5.95/27 that you've assigned. Which of the following explains the router's refusal to take the IP address?A. Class C addresses cannot be assigned to Ethernet interfaces.B. The /27 is an invalid mask.C. It is a broadcast address.D. It is a public IP address.E. It is a private IP address. 32: You are a network technician at Acme, Inc. You are required to divide the 172.12.0.0 network into subnets. Each subnet must have the capacity of 458 IP addresses. Also, according to the requirements, you must provide the maximum number of subnets. Which subnet mask should you use?A. 255.255.255.254B. 255.255.254.0C. 255.255.240.254D. 255.255.0.0 33: What is the subnetwork and broadcast IP address of 192.168.2.37 with the subnet mask of255.255.255.248?A. 192.168.2.24/192.168.2.31B. 192.168.2.32/192.168.2.39C. 192.168.2.40/192.168.2.47D. 192.168.2.48/192.168.2.55E. 192.168.2.56/192.168.2.63 34: One of your co-workers at Acme, Inc., needs to convert the binary number 11011010 into a decimal. What is the decimal equivalent?A. 218B. 219C. 220E. 222 35: One of your co-workers at Acme, Inc., needs to convert the binary number 01011010 into a decimal. What is the decimal equivalent?A. 75B. 83C. 90D. 97 36: One of your co-workers at Acme, Inc., needs to convert the binary num b e r 1 1 0 1 0 1 1 0 i n t o a d e c i m a l . W h a t i s t h e d e c i m a l e q u i v a l e n t ? / p > p b d s f i d = " 2 1 0 " > A . 1 9 8 / p > p b d s f i d = " 2 1 1 " > B . 2 1 4 / p > p b d s f i d = " 2 1 2 " > C . 2 5 2 / p > p b d s f i d = " 2 1 3 " > D . 2 5 5 3 7 : O n e o f y o u r c o - w o r k e r s a t A c m e , I n c . , n e e d s t o c o n v e r t t h e b i n a r y n u m b e r 1 0 1 1 0 1 1 0 i n t o a d e c i m a l . W h a t i s t h e d e c i m a l e q u i v a l e n t / p > p b d s f i d = " 2 1 4 " > A . 1 8 2 / p > p b d s f i d = " 2 1 5 " > B . 1 9 2 / p > p b d s f i d = " 2 1 6 " > C . 2 0 2 / p > p b d s f i d = " 2 1 7 " > D . 2 1 2 3 8 : Y o u a r e c o n f i g u r i n g a s u b n e t f o r t h e A c m e , I n c . , b r a n c h o f f i c e i n B e i j i n g . Y o u n e e d t o a s s i g n I P a d d r e s s e s t o h o s t s i n t h i s s u b n e t . Y o u h a v e b e e n g i v e n t h e s u b n e t m a s k o f 2 5 5 . 2 5 5 . 2 5 5 . 2 2 4 . W h i c h o f t h e s e I P a d d r e s s e s w o u l d b e v a l i d ? ( C h o o s e t h r e e . ) / p > p b d s f i d = " 2 1 8 " > A . 1 5 . 2 3 4 . 1 1 8 . 6 3 / p > p b d s f i d = " 2 1 9 " > B . 9 2 . 1 1 . 1 7 8 . 9 3 / p > p b d s f i d = " 2 2 0 " > C . 1 3 4 . 1 7 8 . 1 8 . 5 6 / p > p b d s f i d = " 2 2 1 " > D . 1 9 2 . 1 6 8 . 1 6 . 8 7 / p > p b d s f i d = " 2 2 2 " > E . 2 0 1 . 4 5 . 1 1 6 . 1 5 9 / p > p b d s f i d = " 2 2 3 " > F . 2 1 7 . 6 3 . 1 2 . 1 9 2 3 9 : Y o u a r e a n e t w o r k t e c h n i c i a n a t A c m e , I n c . Y o u h a v e s u b n e t t e d t h e 2 0 8 . 9 8 . 1 1 2 . 0 n e t w o r k w i t h a / 2 8 m a s k . Y o u r b o s s a s k s y o u h o w m a n y u s a b l e s u b n e t w o r k s a n d u s a b l e h o s t a d d r e s s e s p e r s u b n e t t h i s w i l l p r o v i d e . W h a t s h o u l d y o u t e l l h e r , a s s u m i n g y o u r r o u t e r i s u s i n g i p s u b n e t - z e r o ? / p > p b d s f i d = " 2 2 4 " > A . 62 n e t w o r k s a n d 2 h o s t s / p > p b d s f i d = " 2 2 5 " > B . 6 n e t w o r k s a n d3 0 h o s t s / p > p b d s f i d = " 2 2 6 " >C . 8 n e t w o r k s a n d 3 2 h o s t s / p > p b d s f i d = " 2 2 7 " >D . 1 6 n e t w o r k s a n d 1 6 h o s t s / p > p b d s f i d = " 22 8 " > E . 1 6 n e t w o r k s a n d 1 4 h o s t s 4 0 : W h a t i s a d i s a d v a n t a g e o f u s i n g a c o n n e c t i o n - o r i e n t ed p r o t o c o l s u c h a s T C P ? / p > p b d s f i d = " 2 2 9 " > A . P a c ke t a c k n o w l e d g m e n t m i g h t a d d o v e r h ea d . / p > pb d s f i d = " 2 3 0 " > B . P ac k e t s a r e n o t t a g g ed w i t h se q u e n c e n u m b e r s . / p > p b d sf i d = " 23 1 " > C . L o s s o r d u p l i c a t i o n o f d a t a p a c k e t s i s m o r e l i k e l y t o o c c u r . / p > p b d s f i d = " 2 3 2 " > D . Th e a p p l i c a t i o n l a y e r m u s t a s s u m e r e s p o n s i b i l i t y f o r t h e c o r r e c t s e q u e n c i n g o f t h e d a t a p ac k e t s . 4 1 : Y o u a r e a n e t w o r k t e c h n i c i a n a t A c m e , I n c . Y o u h a v e s u b n e t t ed t he 1 9 2 . 1 6 8 . 7 2 .0 n e t w o r k w i t h a / 3 0 m a s k f o r c o n n e c t i o n s b e t w e e n y o u r r o u t e r s . Y o u r b o s s a s k s y o u h o w m a n y u s a b l e s u b n e t w o r k s a n d u s a b l e h o s t a d d r e s s e s p e r s u b n e t t h i s w i l l p r o v i d e . W h a t s h o u l d y o u t e l l h e r , a s s u m i n g y o u r r o u t e r c a n n o t u s e i p s u b n e t - z e r o ? / p > p b d s f i d = " 2 3 3 " > A . 6 2 n e t w o r k s a n d 2 h o s t s / p > p b d s f i d = " 2 3 4 " > B . 6 n e t w o r k s a n d 3 0 h o s t s / p > p b d s f i d = " 2 3 5 " > C .8 n e t w o r k s a n d 3 2 h o s t s / p > p b d s f i d = " 2 3 6 " > D . 1 6 n e t w o r k s a n d 1 6 h o s t s / p > p b d s f i d = " 2 3 7 " > E . 1 4 n e t w o r k s a n d 1 4 h o s t s 4 2 : W h i c h o f t h e f o l l o w i n g I P a d d r e s s e s a r e c o n s i d e r e d " n e t w o r k " a d d r e s s e s w i t h a / 2 6 p r e f i x ? ( C h o o s e t w o . ) / p > p b d s f i d = " 2 3 8 " > A . 1 6 5 . 2 0 3 . 2 . 0 / p > p b d s f i d = " 2 3 9 " > B . 1 6 5 . 2 0 3 . 5 . 1 9 2 / p > p b d s f i d = " 2 4 0 " > C . 1 6 5 . 2 0 3 . 6 . 6 3 / p > p b d s f i d = " 2 4 1 " > D . 1 6 5 . 2 0 3 . 6 . 1 9 1 / p > p b d s f i d = " 2 4 2 " > E . 1 6 5 . 2 0 3 . 8 . 2 5 5 4 3 : I d e n t i f y t h r e e v a l i d h o s t s i n a n y s u b n e t o f 1 9 2 . 1 6 8 . 3 2 . 0 , a s s u m i n g t h e s u b n e t m a s k u s e d i s 2 5 5 . 2 5 5 . 2 5 5 . 2 4 0 . ( C h o o s e t h r e e . ) / p > p b d s f i d = " 2 4 3 " > A . 1 9 2 . 1 6 8 . 3 2 . 3 3 / p > p b d s f i d = " 2 4 4 " > B . 1 9 2 . 1 6 8 . 3 2 . 1 1 2 / p > p b d s f i d = " 2 4 5 " > C . 1 9 2 . 1 6 8 . 3 2 . 1 1 9 / p > p b d s f i d = " 2 4 6 " > D . 1 9 2 . 1 6 8 . 3 2 . 1 2 6 / p > p b d s f i d = " 2 4 7 " > E . 1 9 2 . 1 6 8 . 3 2 . 1 7 5 / p > p b d s f i d = " 2 4 8 " > F . 1 9 2 . 1 6 8 . 3 2 . 2 0 8 4 4 : A C l a s s C n e t w o r k a d d r e s s h a s b e e n s u b n e t t e d w i t h a / 2 7 m a s k . W h i c h o f t h e f o l l o w i n g a d d r e s s e s i s a b r o a d c a s t a d d r e s s f o r o n e o f t h e r e s u l t i n g s u b n e t s ? / p > p b d s f i d = " 2 4 9 " > A . 1 9 8 . 5 7 . 7 8 . 3 3 / p > p b d s fi d = " 2 5 0 " > B . 1 9 8 . 5 7 . 7 8 . 6 4 / p > p b d s f i d = " 2 5 1 " > C . 1 9 8 . 5 7 . 7 8 . 9 7 / p > p b d s f i d = " 2 5 2 " > D . 1 98 . 5 7 . 7 8 . 9 7 / p > p b d s f i d = " 2 5 3 " > E . 1 9 8 . 5 7 . 7 8 . 1 5 9 / p > p b d s f i d = " 2 5 4 " > F . 1 9 8 . 5 7 . 7 8 . 2 5 4 4 5 : W h a t i s t h e s u b n e t w o r k a d d r e s s f o r a h o s t w i t h I P a d d r e s s 1 6 5 . 1 0 0 . 5 . 6 8 / 2 8 ? / p > p b d s f i d = " 2 5 5 " > A . 1 6 5 . 1 0 0 . 5 . 0 / p > p b d s f i d = " 2 5 6 " > B . 1 6 5 . 1 0 0 . 5 . 3 2 / p > p b d s f i d = " 2 5 7 " > C . 1 6 5 . 1 0 0 . 5 . 6 4 / p > p b d s f i d = " 2 5 8 " > D . 1 6 5 . 1 0 0 . 5 . 6 5 / p > p b d s f i d = " 2 5 9 " > E . 1 6 5 . 1 0 0 . 5 . 3 1 / p > p b d s f i d = " 2 6 0 " > F . 1 6 5 . 1 0 0 . 5 . 1 4 6 : Y o u r b o s s w a n t s t o k n o w w h a t T C P s t a n d s f o r . W h a t d o y o u t e l l h i m ? / p > p b d s f i d = " 2 6 1 " > A . T r a n s m i s s i o n C h e c k P r o t o c o l / p > p b d s f i d = " 2 6 2 " > B . T r a n s p o r t C h e c k P r o t o c o l / p > p b d s f i d = " 2 6 3 " > C . T r a n s m i s s i o n C o n t r o l P r o t o c o l / p > p b d s f i d = " 2 6 4 " > D . T r a n s p o r t C o n t r o l P r o t o c o l 4 7 : Y o u r b o s s w a n t s t o k n o w w h a t U D P s t a n d s f o r . W h a t d o y o u t e l l h i m ? / p > p b d s f i d = " 2 6 5 " > A . U n r e l i a b l e D a t a P r o t o c o l / p > p b d s f i d = " 2 6 6 " > B . U n r e l i a b l e D a t a P r o g r a m / p > p b d s f i d = " 2 6 7 " > C . U s e r - D e f i n e d P r o t o c o l / p > p b d s f i d = " 2 6 8 " > D . U s e r D a t a g r a m P r o t o c o l 4 8 : W h i c h o f t h e f o l l o w i n g s t a t e m e n t s a c c u r a t e l y d e s c r i b e s U D P ? / p > p b d s f i d = " 2 6 9 " > A . U D P c o p i e s f i l e s b e t w e e n a c o m p u t e r a n d a s y s t e m r u n n i n g r s h d , t h e r e m o t e s h e l l s e r v i c e ( d a e m o n ) . / p > p b d s f i d = " 2 7 0 " > B . U D P i s a m e m b e r o f t h e T C P / I P s u i t e o f p r o t o c o l s t h a t g o v e r n s t h e e x c h a n g e o f e l e c t r o n i c m a i l b e t w e e n m e s s a g e t r a n sf e r ag e n t s . / p > p b d s f i d = " 2 7 1 " > C . U D P i s a m e m b e r o f th e T C P / I P s ui t e o f p r o t o c o l s a n d i s u s e d t o c o p y f i l e s b e t w e e n t w o c o m p u t e r s o n t h e I n t e r n e t . B o t h c o m p u t e r s m u s t s u p p o r t t h e i r r e s p e c t i v e r o l e s : o n e m u s t b e a c l i e n t , a n d t h e o t h e r a s e r v e r . / p > p b d s f i d = " 2 7 2 " > D . U D P i s a T C P c o m p l e m e n t t h a t o f f e r s a c o n n e c t i o n l e s s d a t a g r a m s e r v i c e g u a r a n t e e i n g n e i t h e r d e l i v e r y n o r c o r r e c t s e q u e n c i n g o f d e l i v e r e d p a c k e t s ( m u c h l i k e I P ) . 4 9 : W h i c h o f t h e f o l l o w i n g h o s t a d d r e s s e s a r e m e m b e r s o f n e t w o r k s t h a t c a n b e r o u t e d a c r o s s t h e p u b l i c I n t e r n e t ( C h o o s e t h r e e . ) / p > p b d s f i d = " 2 7 3 " > A . 1 0 . 2 0 . 1 2 . 6 4 / p > p b d s f i d = " 2 7 4 " > B . 1 7 2 . 1 6 . 3 2 . 12 9 / p > p b d s f i d = " 2 7 5 " > C . 1 7 2 . 6 4 .3 2 . 34 / p > p b d s f i d = " 2 7 6 " > D . 1 9 2 . 1 6 8 . 2 3 . 25 2 / p > p b d s f id = " 2 7 7 " > E . 1 9 6 . 1 0 4 . 1 2 . 9 5 / p > p b d s f i d = " 2 7 8 " > F . 2 1 4 . 1 9 2 . 4 8 . 2 5 4 5 0 : Y o u a re c o n n e c t i n g y o u r S e r i a l 0 / 1 i n t e rf a c e t o t h e I n t e r n e t . W h i c h o f t h e f o l l o w i ng n e e d t o b e d o n e f o r th e c o n n e c ti o n t o w o r k ? ( C h o o s e t w o . ) / p > p b d s f i d = " 2 7 9 " > A . A s s i g n a p u b l i c I P a d d r e s s . / p > p b d s f i d = " 2 8 0 " > B . U s e t h e s h u t d o w n c o m m a n d . / p > p b d s f i d = " 2 8 1 " > C . U s e t h e n o s h u t d o w n c o m m a n d . / p > p b d s f i d = " 2 8 2 " > D . M a k e s u r e t h e i n t e r f a c e i s r u n n i n g i n f u l l - d u p l e x . / p >。

ccna测试题及答案

ccna测试题及答案CCNA测试题及答案一、选择题1. 在Cisco设备上，以下哪个命令用于查看当前的路由表？A. show ip routeB. show running-configC. show interface statusD. show version答案：A2. 以下哪个协议用于在网络中自动发现其他设备？A. ARPB. CDPC. ICMPD. TCP答案：B3. 以下哪个命令用于配置Cisco设备上的接口？A. configure terminalB. interfaceC. ip addressD. hostname答案：A二、填空题4. 在Cisco设备上，使用命令_________可以查看接口的配置信息。

答案：show interface5. 静态路由配置中，_________命令用于指定下一跳地址。

答案：ip route6. 动态路由协议可以自动适应网络变化，其中_________是最常见的一种。

答案：RIP（路由信息协议）三、简答题7. 请简述VLAN（虚拟局域网）的作用。

答案：VLAN是一种将局域网内不同物理位置的设备划分为同一逻辑网络的技术，主要用于隔离广播域，提高网络的安全性和效率。

8. 描述交换机和路由器在网络中的基本功能。

答案：交换机主要用于局域网内部，通过MAC地址表来转发数据帧，实现数据包在局域网内的快速交换。

路由器则工作在网络层，使用IP地址来转发数据包，连接不同的网络，并进行路径选择。

四、计算题9. 假设一个子网掩码为255.255.255.192，计算这个子网的可用IP地址范围。

答案：可用IP地址范围为192.168.1.0到192.168.1.62（包含两端）。

五、实验题10. 请根据以下配置文件，列出Router1的接口配置信息。

```Router1show running-configinterface FastEthernet0/0ip address 192.168.1.1 255.255.255.0duplex autospeed auto!interface FastEthernet0/1no ip addressshutdown!interface Serial0/0/0ip address 10.0.0.1 255.255.255.252clock rate 64000!router ospf 1network 192.168.1.0 0.0.0.255 area 0network 10.0.0.0 0.0.0.3 area 0!```答案：- FastEthernet0/0: IP地址为192.168.1.1，子网掩码为255.255.255.0，双工模式和速度均为自动。

思科认证考试(CCNA)考试模拟题01—19及答案(1)-思科认证试题

思科认证考试（ＣＣＮＡ）考试模拟题０１—１９及答案(1)-思科认证试题－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－Below are questions 1-19. To see an explanation for each question, please refer to the explanation link below the question or select explanations on the navigation bar to the left. Questions1. [OxNx] During a TFTP transfer using Cisco Routers what is the numeric value, in decimal, of the destination port field of the User Datagram Protocol (UDP) header?a) 96b) 47c) a random number above 1024d) 69e) none of the above2. [CxNx] What is the standard encapsulation method used by Cisco routers for the Internet Protocol (IP) on it’s Ethernet interfaces?a) SNAPb) ARPAc) NOVELL-ETHERd) DARPAe) Ethernet_802.33. [CxNx] What will be the correct command on a Cisco router to set the IP address of an interface assuming you are at the "router(config-if)#" prompt?a) ip address 1.1.1.1 255.255.255.0b) ip address 1.1.1.1c) ip 1.1.1.1d) ip 1.1.1.1 255.255.255.0e) none of the above4. [CxNx] Which commands will display the IP addresses of all interfaces on a Cisco Router? (Choose all that apply)a) show ip routeb) show ip addressc) show ip interfaced) show interfacee) display ip addresses5. [CxNx] Which of the following commands will display the contents of the ARP cache of your Cisco router?a) show ip arp cacheb) show ip routec) show ip arpd) show arpe) there is no way to display the ARP cache6. [CxNx] Reverse Address Resolution Protocol (RARP) is the process:a) Where an IP host resolves it’s IP address by broadcasting it’s MAC address to the network anda BOOTP server assigns it an IP address.b) Where an IP host resolves it’s MAC address by broadcasting to the local network it’s IP address.c) Where an IP host tries to resolve the MAC address of a destination by sending a network broadcast. The destination responds to the broadcast with it’s MAC address.d) Where an IP host resolves a destination IP address by sending a broadcast on the local network and the destination host responds with it’s IP address.e)There is no such process.7. [OxNx] Which of the following applications requires the connection-oriented layer four protocol, TCP? (Choose all that apply)a) Telnetb) FTPc) TFTPd) SNMPe) none of the above8. [RxNx] Which of the following are link state Routing Protocols.(Choose all that apply.)a) IPb) O感谢阅读，欢迎大家下载使用！。

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CCNA考试自测题第1卷（三）(1)-思科认证试题
32) What is the sequence number in a TCP header used for (在T C P报头中的顺序号的作用是什么)？
A. Acknowledgments
B. Reordering of the octets received
C. Rejecting duplicate octets
33) Variable sliding windows provide an explicit mechanism for notifying TCP if an intermediate node (for example, a router) becomes congested (在中间节点，例如一个路由器拥塞的情况下，可变滑动窗口提供了通知T C P的显式机制)。

A. True
B. False
34) Which of the following parameters is not a part of UDP header (下面的哪一个参数不是U D P报头的一部分)？
A. Source port
B. Urgent pointer
C. Checksum
D. Length
E. Destination port
35) When a router has been configured for UDP flooding, the source address might change,but the destination address will not change as the datagram propagates through the network (当一个路由器已经配置为U D P泛洪时，当数据报在网络上传播的过程中，源地址可能改变，但是目的地址不会改变)？
A. True
B. False
36) The spanning-tree algorithm allows (生成树算法允许)：
A. Forwarding of packets with no control
B. Forwarding of broadcasts to an interface which already has received the broadcast
C. Prevention of duplication of forwarding of packets
D. A and B only
37) IP helper addresses are a form of _ _ _ _ _ _ _ _ _ _ _ _ _ _ addressing and require the command specification of _ _ _ _ _ _ _ _ _on every interface receiving broadcasts that need to be forwarded (IP辅助地址是一种什么类型的寻址方法，在每一个接收到需要转发的广播接口上需要什么命令说明)？。