[单选题]下面有关交换机的描述中，正确的是（）

正确答案 ：C

交换机独占带宽

[单选题]Which one of the following characteristics is true regarding the use of hubs and switches?

正确答案 ：E

Switches increase the number of collision domains in the network.

解析：解析：Explanation:Switchesincreasesthenumberofcollisionsdomainsinthenetwork.SwitchesthatareconfiguredwithVLANswillreducethesizeofthecollisiondomainsbyincreasingthenumberofcollisiondomainsinanetwork,butmakingthemsmallerthanthatofonebig,flatnetwork.IncorrectAnswers:A.SwitchesarecapableofVLANconfigurations,buthubsarenot.B.Hubsaregenerallytheleastcostlymethodpossibletoconnectmultipledevicestogetherinanetwork.C.Switchesforwardbroadcastsandmulticasts,bydefault,toallportswithinthesameVLAN.Onlyroutersblockallbroadcasttrafficbydefault.D.Switchesandhubscanbeequallyefficientinprocessingframes,intheory.Inpractice,switchesaregenerallymoreefficientastheyusuallyhavemoreCPUandmemoryallocatedtothem,andaregenerallymuchmoreexpensivethanasimplehub.

[单选题]路由器下，由一般用户模式进入特权用户模式的命令是：（）

正确答案 ：A

enable

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