ccna考试题库

QUESTION 37

What are two characteristics of RIPv2? (Choose two.)

A. classful routing protocol B. variable-length subnet masks C. broadcast addressing D. manual route summarization E. uses SPF algorithm to compute path Answer: BD

Explanation/Reference: A：有类路由协议，错误 B：可变长度子网掩码，正确 C：采用广播地址更新，错误 D：手动路由汇总，正确

E:使用spf算法计算路径，错误。 QUESTION 38

Which two Ethernet fiber-optic modes support distances of greater than 550 meters? A.1000BASE-CX B. 100BASE-FX C. 1000BASE-LX D. 1000BASE-SX

E. 1000BASE-ZX Answer: CE

Explanation/Reference: A：最长距离25米 B：最长距离100米 C：最长距离3000米 D：最长距离550米 E：最长距离70千米 QUESTION 39

What 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. Answer: AD

Explanation/Reference:

考点：考查距离矢量路由协议特性 A：周期性更新，正确

B：发送整个路由表到整个路由域，错误，只发送给邻居

C：使用SPF算法，错误

D：依靠邻居发送更新来更新路由表，正确 E：在数据库中维护整个网络的拓扑。错误

Which command shows if an access list is assigned to an interface?

A. show ip interface [interface] access-lists B. show ip access-lists interface [interface] C. show ip interface [interface] D. show ip access-lists [interface] Answer: C

Explanation/Reference: QUESTION 42

Refer 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. Answer: A

Explanation/Reference:

show ip dhcp conflict命令可以查看哪些ip地址在使用上有冲突。

有冲突的地址不再分配出去。 A：地址被删除直到冲突解决，正确 B:地址保留直到冲突解决，错误 C/D：答案片面。

E：当冲突解决后，地址会被显示。错误。 QUESTION 44

Refer to the exhibit. If number 2 is selected from the setup script, what happens when the user runs

setup

from 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. Answer: A

Explanation/Reference: [0]不保存进入IOS命令配置模式 [1]不保存返回设置模式 [2]保存退出

A：设置和改动被保存到配置脚本

B：为有效地重新开始配置，如果路由器是第一次启动的配置。

C：如果配置了密码，设置不会运行

D：设置不可用，因为它只能在没有配置存在时才有效 QUESTION 49

Which 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. Answer: AE

Explanation/Reference: 考点：考查vlan知识点。

A：缺省都存在vlan1，端口都属于vlan1，正确 B：CDP信息只发送到vlan1002，错误，vlan1002是fddi网络的vlan号。

C：缺省情况交换机IP配置在vlan1005，错误，vlan1005trnet网络的vlan号。缺省在vlan1里面。 D：vlan1002-1005自动生成并不能被删除，正确，他们都是被保留的特殊vlan。

QUESTION 56 没有理解什么意思

Refer 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. Answer: D

Explanation/Reference:

由图中提示信息可以看出，源为10.10.0.2已经有个一个转换，所以后续的数据包快速转发。 What 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. Answer: AEF

Explanation/Reference:

A：VLAN在交换网络中建立广播域，正确

B：利用VLAN的数据包过滤，增强网络的安全性。错误，没有这个特性。

C：提供了在大型网络中的保护IP地址的方法。错误 D：提供低延迟互联网络替代路由网络。错误 E：vlan允许基于逻辑划分的网络访问，不是物理位置。正确。

F：VLAN可以大大简化添加，移动或更改网络上的主机。正确。 QUESTION 61

An administrator would like to configure a switch over a virtual terminal connection from locations outside

of the local LAN. Which of the following are required in order for the switch to be configured from a remote

location? (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. Answer: AC

Explanation/Reference:

要想远程管理VLAN，1、交换机配置IP，2、路由可达

QUESTION 65

Which router IOS commands can be used to troubleshoot LAN connectivity problems? (Choose three.) A. ping B. tracert C. ipconfig D. show ip route E. winipcfg F. show interfaces Answer: ADF

Explanation/Reference: A：测试连通性 D：查看是否有路由 F：查看接口是否可用

QUESTION

Which 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.允许用户从逻辑上进行分组

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. Answer: BCE

Explanation/Reference: 考查VLAN的特点

A：增加冲突域的大小，错误 B：允许逻辑划分网段，正确

C：增强网络安全，正确。不同vlan不能直接通信。 D：当减少冲突域时增加广播域的大小。错误 E：减少广播域的大小时增加了广播域个数。正确。 F:简化交换机管理。答非所问。 QUESTION 71

Which characteristics are representative of a link-state routing protocol? (Choose three.) A. provides common view of entire topology B. exchanges routing tables with neighbors C. calculates shortest path

D. utilizes event-triggered updates E. utilizes frequent periodic updates Answer: ACD

Explanation/Reference: 链路状态路由协议有协议特点？

A:提供查看拓扑的命令，正确。show ip ospf database B：邻居之间交换路由信息，错误。交换LSA C：计算最短路径，正确。 D：利用触发更新，正确 E：利用周期更新，错误。 QUESTION 73

Use the output from the router shown in the graphic above to determine which of the following are correct. (Choose two.)

A. Router John uses a link-state routing protocol.

B. Router John will receive routing updates on the Serial0/0 interface.

C. Router John will receive routing updates on the Serial0/1 interface.

D. Router John will send routing updates out the Serial0/0 interface.

E. Router John will send routing updates out the

FastEthernet0/0 interface.

F. Router John will send routing updates out the Serial0/1 interface. Answer: BD

Explanation/Reference:

由图中几处画红线的地方可知只有s0/0发送和接受路由信息。

QUESTION 74 2的次方问题

A national retail chain needs to design an IP addressing scheme to support a nationwide network. The

company needs a minimum of 300 sub-networks and a maximum of 50 host addresses per subnet. Working with only one Class B address, which of the following subnet masks will support an appropriate

addressing scheme? (Choose two.) A. 255.255.255.0 B. 255.255.255.128 C. 255.255.252.0 D. 255.255.255.224 E. 255.255.255.192

F. 255.255.248.0 Answer: BE

Explanation/Reference:

需要至少300个子网，每个子网至少50台主机。使用一个B类地址来划分。 A：最多有256个子网，错误 C：只有个子网

D：每个子网只有30个可用IP F：只有32个子网 QUESTION 79

What information does a router running a link-state protocol use to build and maintain its topological

database? (Choose two.) A. hello packets

B. SAP messages sent by other routers C. LSAs from other routers

D. beacons 信息received on point-to-point links E. routing tables received from other link-state routers

F. TTL packets from designated routers Answer: AC

Explanation/Reference:

链路状态路由协议如何维护拓扑数据库？ A：hello包用于维护邻居关系，正确。 B：错误，没有这个概念。 C：通过其他路由器的LSA，正确。 D：从点到点链路接收，错误。答案片面

E：从其他路由器接收路由表，错误。相互间不直接发送路由表。

F：从DR接受TTL包，错误，答非所问。 QUESTION 80

Which statements describe the routing protocol OSPF? (Choose three.) A. It supports VLSM.

B. It is used to route between autonomous systems. C. It confines network instability to one area of the network.

D. It increases routing overhead on the network. E. It allows extensive control of routing updates.

F. It is simpler to configure than RIP v2. Answer: ACE

Explanation/Reference:

A：支持VLSM，正确

B：在AS之间使用，错误。在AS内部使用

C：了不稳定网络的范围，正确。通过划分区域实现。

D：增加了网络的开销，错误。 E：允许路由更新控制，正确。

F：比RIPv2更容易配置，错误，答非所问。 Which of the following are types of flow control? (Choose three.) A. buffering B. cut-through C. windowing

D. congestion avoidance E. load balancing Answer: ACD

Explanation/Reference: 流控制有哪些？ A：缓存 B：直通 C：窗口机制 D：拥塞避免 E：负载均衡。

What can be determined from the line of show ip route output shown in the exhibit? (Choose two.)

注意R =rip 管理距离修改 Rout rip Distance 10

A. The next routing update can be expected in 35 seconds.

B. The IP address 10.10.10.6 is configured on S0/1.

C. The IP address 10.10.10.8 is configured on S0/1.

D. This route is using the default administrative distance.

E. The 10.10.10.8 network is two hops away from this router. Answer: DE

Explanation/Reference:

考点：考查RIP的路由条目。通过RIP学习到一条到达10.10.10.8的路由，下一跳是10.10.10.6，出接口是 s/1。

A：错误。rip更新周期为30s，正常计时器不会超过30 B：错误，这个ip是对端接口ip C：错误。s0/1的ip无法得知 D：正确，rip缺省的管理距离是120 E：正确。 QUESTION 93

Refer to the exhibit. From RouterA, a network administrator is able to ping the serial interface of RouterB

but unable to ping any of the subnets attached to RouterB. Based on the partial outputs in the exhibit, what could be the problem?

A. EIGRP does not support VLSM.

B. The EIGRP network statements are incorrectly configured.

C. The IP addressing on the serial interface of RouterA is incorrect.

D. The routing protocol has summarized on the classful boundary.

E. EIGRP has been configured with an invalid

autonomous system number. Answer: D QUESTION 97

For what two purposes does the Ethernet protocol use physical addresses? (Choose two.) A. to uniquely identify devices at Layer 2 B. to allow communication with devices on a different network

C. to differentiate a Layer 2 frame from a Layer 3 packet

D. to establish a priority system to determine which device gets to transmit first E. to allow communication between different devices on the same network

F. to allow detection of a remote device when its physical address is unknown Answer: AE

Explanation/Reference: 考点：考查mac地址的作用。 A：在二层唯一确定一台设备，正确

B：是设备在不同的网络中通信，错误，不同网络通信需要通过IP地址确定。

C：区别二层和三层帧，错误。

D：确定设备的优先级，错误。没有这个功能。 E：是同一网络的不同设备可以通信，正确

F：当不知道远程设备的物理地址时可以查询，错误。不能跨网段。 QUESTION 98

As a frame leaves a Layer 3 device, the Layer 2 encapsulation information is changed from what it was

when it entered the device. For what two reasons can this happen? (Choose two.)

A. The data is moving from 10BASE-TX to 100BASE-TX.

B. The WAN encapsulation type has changed. C. The data format has changed from analog to digital.

D. The source and destination hosts are in the same subnet.

E. The source and destination MAC addresses have changed. Answer: BE

Explanation/Reference:

考点：数据包转发过程。当数据包离开三层设备时，二层封装哪些信息改变了。

A：从10M网络到100M网络，错误。带宽改变不会改变数据包封装。

B：广域网封装改变，正确。如从HDCL变成PPP C：数据格式从模拟型号变成数据信号，错误，物理层的信号方式变化不会影响二层数据格式。 D：错误。

E：原蜜MAC改变，正确。 QUESTION 99

Which two statements are true regarding EIGRP? (Choose two.)

A. Passive routes简单的说就是：能被路由器路由的协议。例如：IP、IPX、APPLE TALK等are in the process of being calculated by DUAL.

B. EIGRP supports VLSM, route summarization, and routing update authentication.

C. EIGRP exchanges full routing table information with neighboring routers with every update. D. If the feasible successor has a higher advertised distance than the successor route, it becomes the

primary route.

E. A query process is used to discover a replacement for a failed route if a feasible successor is not

identified from the current routing information. Answer: BE

Explanation/Reference:

A：被动路由在路由进程中由dual计算，错误。 B：至此VLSM，路由汇总，认证，正确

C：每次更新都发送全部的路由信息，错误，增量更新。 D：如果可行后继路由器有一个比后继路由器高的通告距离，它会成为主路由条目，错误。

E：如果不存在FS，使用查询进程去发现替代失效的路由信息，正确。

What is an appropriate use of a default route? A. to provide routing to a local web server B. to provide routing from an ISP to a stub network C. to provide routing that will override the configured dynamic routing protocol

D. to provide routing to a destination that is not specified in the routing table and which is outside the local

network Answer: D

Explanation/Reference: 考点：考查缺省路由的特点

A：提供路由到本地web服务器，错误 B：提供从ISP到末节网络的路由，错误

C：提供优先于动态路由协议的路由，错误。根据最长匹配原则，缺省路由最后才匹配。 D：正确 QUESTION 103

Refer to the exhibit. A junior network engineer has prepared the exhibited configuration file. What two

statements are true of the planned configuration for interface fa0/1? (Choose two.)

A. The two FastEthernet interfaces will require NAT configured on two outside serial interfaces. B. Address translation on fa0/1 is not required for DMZ Devices to access the Internet. C. The fa0/1 IP address overlaps with the space used by s0/0.

D. The fa0/1 IP address is invalid for the IP subnet on which it resides.

E. Internet hosts may not initiate connections to DMZ Devices through the configuration that is shown. Answer: BE

Explanation/Reference:

DMZ使用公网地址，不需要做NAT，图中ACL第二条错将DMZ做了NAT，因此造成不能访问 QUESTION 111

Refer to the exhibit. Some 2950 series switches are connected to the conference area of the corporate

headquarters network. The switches provide two to three jacks per conference room to host laptop connections for employees who visit the headquarters office. When large groups of employees come from

other locations, the network administrator often finds that hubs have been connected to wall jacks in the

conference area although the ports on the access layer switches were not intended to support multiple workstations.

What action could the network administrator take to prevent access by multiple laptops through a single

switch port and still leave the switch functional for its intended use?

A. Configure static entries in the switch MAC address table to include the range of addresses used by

visiting employees.

B. Configure an ACL to allow only a single MAC address to connect to the switch at one time. C. Use the mac-address-table 1 global

configuration command to limit each port to one source MAC address.

D. Implement Port Security on all interfaces and use the port-security maximum 1 command to limit port

access to a single MAC address.

E. Implement Port Security on all interfaces and use the port-security mac-address sticky command to

limit access to a single MAC address. F. Implement Port Security at global

configuration mode and use the port-security maximum 1 command

to allow each switch only one attached hub. Answer: D

Explanation/Reference:

考点：考查交换机端口安全。题目想实现一个端口只接入一台设备。

A：配置静态mac地址表。错误。无法达到效果。 B：配置ACL允许同一个时刻仅一个mac地址连接到交换机。错误。

C：在全局配置模式使用mac-address-table命令每个端口一个源mac地址。错误，无法实现。 D：在所有端口使用port security和maximum 1一

个端口允许一个mac地址，正确。

E：部署port security和port-security mac-address sticky命令，错误，无法实现。

F：在所有端口使用port security和maximum 1一个端口允许一个hub，错误，一个hub下面可以接多台 PC。

Running both IPv4 and IPv6 on a router simultaneously is known as what? A. 4to6 routing B. 6to4 routing C. binary routing D. dual-stack routing E. NextGen routing Answer: D

Explanation/Reference: 考点：考查IPv4和IPv6共存。

同时使用IPv4和IPv6时称为双栈路由。 QUESTION 113

What are three IPv6 transition mechanisms? (Choose three.) A. 6to4 tunneling B. VPN tunneling

C. GRE tunneling D. ISATAP tunneling E. PPP tunneling F. Teredo tunneling Answer: ADF

Explanation/Reference:

考点：考查IPv4-->IPv6的过度机制。主要有三种： 6to4隧道：

ISATAP tunneling：站内自动隧道寻址机制 teredo tunneling：Teredo目前尚为IEIF草案，将IPv6数据包包在UDP／IPv4 数据包中传送。。 QUESTION 118

How does using the service password encryption command on a router provide additional security? A. by encrypting all passwords passing through the router

B. by encrypting passwords in the plain text configuration file

C. by requiring entry of encrypted passwords for access to the device

D. by configuring an MD5 encrypted key to be used by routing protocols to validate routing

exchanges

E. by automatically suggesting encrypted passwords for use in configuring the router Answer: B

Explanation/Reference:

当使用这条命令后，所有在路由器上配置是密码都被加密。

A:所有通过路由器的密码都被加密。错误 B：正确

C：当访问设备时提供加密的密码。错误

D：通过配置一个加密的密钥为路由协议使用，错误 E：在用户配置路由器时自动建议加密密码。错误 Refer to the exhibit. What statement is true of the configuration for this network?

A. The configuration that is shown provides inadequate outside address space for translation of the

number of inside addresses that are supported. B. Because of the addressing on interface FastEthernet0/1, the Serial0/0 interface address will not support

the NAT configuration as shown.

C. The number 1 referred to in the ip nat inside souce command recerences access-list number 1. D. ExternalRouter must be configured with static routers to network 172.16.2.0/24 Answer: C

Explanation/Reference:

A：该配置显示了内部全局地址不足以分配给所有内部局部地址，错误。使用了overload关键字，为PAT。 B:不支持NAT转换，错误。

C:ip nat insid source 1中1为access list 1 D：extemalrouter必须配置一条到172.16.2.0/24,错误。