[单选题]After working all night and successfully configuring a Cisco router for the Ezonexam network you save your changes on the startup config, reboot the router, and go out for a cigarette. When you return, none of your changes are active and the router boots to the initial configuration mode! Which of the choices below indicates the source of your problem?

正确答案 ：C

Router configuration-register set to bypass startup configuration

解析：解析：Explanation:

[单选题]IP地址为：192.168.50.70，掩码为：255.255.255.248，则该IP地址所在子网的子网号为（）

正确答案 ：B

192.168.80.64

[单选题]You have a class C network, and you need to design it for 5 usable subnets with each subnet handling a minimum of 18 hosts each. Which of the following network masks should you use?

正确答案 ：D

255.255.255.224

解析：解析：Explanation:ThedefaultsubnetmaskforclassCnetworkis255.255.255.0.Ifonehastocreate5subnets,then3bitsarerequired.With3bitswecancreate8subnets.Theremaining5bitsareusedforHosts.Onecancreate30hostsusing5bitsinhostfield.Thismatcheswiththerequirement.IncorrectAnswers:A,B:ThisisanillegalsubnetmaskforaclassCnetwork,asthethirdoctetcannotbedividedwhenusingaclassCnetwork.C:ThisisthedefaultsubnetmaskforaclassCnetwork.Itprovidesforonenetwork,with254usablehostIPaddresses.E:Thissubnetmaskwillprovidefor14separatenetworkswith14hostseach.Thisdoesnotmeettherequirementofaminimumof18hosts.

[单选题]常见的LSA有几种类型()

正确答案 ：C

6

[单选题]Your network uses the172.12.0.0 class B address. You need to support 459 hosts per subnet, while accommodating the maximum number of subnets. Which mask would you use?

正确答案 ：D

255.255.254.0.

解析：解析：Explanation:Toobtain459hoststhenumberofhostbitswillbe9.Thiscansupportamaximumof510hosts.Tokeep9bitsforhostsmeansthelastbitinthe3rdoctetwillbe0.Thisgives255.255.254.0asthesubnetmask.

[单选题]What is the purpose of the spanning-tree algorithm in a switched LAN?

正确答案 ：C

To prevent switching loops in networks with redundant switched paths.

解析：解析：Explanation:STPisusedinLANswithredundantpathsorroutestopreventloopsinalayer2switchedorbridgedLAN.IncorrectAnswers:A,B:TheprimarypurposeofSTPistopreventloops,notformonitoringormanagementofswitchesorVLANs.D.VLANsareusedtosegmentaLANintomultiplecollisiondomains,buttheSTPprocessalonedoesnotdothis.E.Routersareusedtopreventroutingloopsatlayer3oftheOSImodel.STPoperatesatlayer2.

[单选题]关于静态NAT，下面（）说法是正确的。

正确答案 ：C

静态NAT将内部地址一对一静态映射到内部全局地址

[单选题]在路由表中到达同一网络的路由有：静态路由、RIP路由、IGRP路由，OSPF路由，则路由器会选用哪条路由传输数据：()

正确答案 ：A

静态路由

[单选题]路由器上，设置端口速率的命令是（）

正确答案 ：B

bandwidth

[多选题]When you compare the differences between half-duplex and full-duplex Ethernet, which of the following characteristics are exclusive to half-duplex? (Select two answer choices)

正确答案 ：AD

Half-duplex Ethernet operates in a shared collision domain.

Half-duplex Ethernet has lower effective throughput.

解析：解析：Explanation:

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