正确答案: E

The network layer

题目：While troubleshooting a connectivity problem on the network, you issue the ping command from your PC command prompt, but the output shows "request times out."At which OSI layer is this problem associated with?

解析：解析：Explanation:

查看原题查看所有试题

学习资料的答案和解析：

[多选题]CDP is being used throughout the Ezonexam network. What are two reasons why the Ezonexam network administrator would use CDP? (Choose two)

To obtain the IP Address of a connected device in order to telnet to the device

To verify Layer 2 connectivity between two devices when Layer 3 fails

[单选题]IP地址为：192.168.50.70，掩码为：255.255.255.248，则该IP地址所在子网的广播地址为（）

192.168.50.71

[单选题]路由器上，命令“show int s0”的显示结果为：Serial0 is up,line protocol is down出现该结果的可能原因是（）

两端设备协议不一致

[单选题]During the boot sequence, a Ezonexam 2800 series router needs to locate and load an operating system. What is the default order the router uses to find an operating system?

Flash, TFTP server, ROM

解析：解析：Explanation:BootinguptheRouter:CiscorouterscanbootCiscoIOSsoftwarefromtheselocations:1.Flashmemory2.TFTPserver3.ROM(notfullCiscoIOS)Multiplesourceoptionsprovideflexibilityandfallbackalternatives.

[多选题]The Ezonexam network administrator issues the ping 192.168.2.5 command and successfully tests connectivity to a host that has been newly connected to the network. Which protocols were used during the test? (Choose two)

ARP

ICMP

解析：解析：Explanation:ARPfindsthehardwareaddressofahostfromaknownIPaddress.Here'showitworks:whenIPhasadatagramtosend,itmustinform.aNetworkAccessprotocol,suchasEthernetorTokenRing,ofthedestination'shardwareaddressonthelocalnetwork.(Ithasalreadybeeninformedbyupper-layerprotocolsofthedestination'sIPaddress.)IfIPdoesn'tfindthedestinationhost'shardwareaddressintheARPcache,itusesARPtofindthisinformation.ICMPworksattheNetworklayerandisusedbyIPformanydifferentservices.ICMPisamanagementprotocolandmessagingserviceproviderforIP.ItsmessagesarecarriedasIPdatagrams.RFC1256isanannextoICMP,whichaffordshosts'extendedcapabilityindiscoveringroutestogateways.Periodically,routeradvertisementsareannouncedoverthenetwork,reportingIPaddressesfortherouter'snetworkinterfaces.Hostslistenforthesenetworkinfomercialstoacquirerouteinformation.Aroutersolicitationisarequestforimmediateadvertisementsandmaybesentbyahostwhenitstartsup.

[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?

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.