[单选题]以下（）LSA类型是ASBR来宣告外部路由信息的。（）

正确答案 ：E

类型5

[单选题]PPP工作在OSI的哪一层（）

正确答案 ：B

数据链路层

[单选题]An administrator issues the show ip interface s0/0 command and the output displays that interface Serial0/0 is up, line protocol is up.What does "line protocol is up" specifically indicate about the interface?

正确答案 ：C

Keepalives are being received on the interface.

解析：解析：Explanation:

[多选题]The LAN needs are expanding at the Ezonexam corporate office, which is quickly growing. You are instructed to enlarge the area covered by a single LAN segment on the Ezonexam network.Which of the following are layer 1 devices that you can use? (Choose all that apply.)

正确答案 ：DE

A hub

A repeater

解析：解析：Explanation:

[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.

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