Which of the following are forms of gigabit Ethernet that require the use of fiber optic cables？（）

单项选择题WhichofthefollowingnetworkdevicesoperatesonLayer1oftheOSImodel？（）

A.Hub
B.Switch
C.Router
D.Bridge

单项选择题Anetworktechnicianisinstallingaseriesofthreeaccesspointstocovertheentirewingofabuilding.Eachaccesspointhasawiredconnectionand802.11gisbeingusedforthewirelesstransmission.Whichofthefollowingchannelsshouldbeusedfortheaccesspoints？（）

A.Channels 1-6-11
B.Channels 1-3-5
C.Channels 7-11-1
D.Channels 2-4-6

单项选择题Atechniciannoticesthatwhentryingtopingaworkstationbynetworknametheworkstationdoesnotreplybackoverthenetwork.TheworkstationispartofthedomainandisabletogettotheInternet.Whichofthefollowingisthecauseoftheproblem？（）

A.Faulty cable on the workstation
B.Wrong host name on the workstation
C.Wrong WINS on the workstation
D.Incorrect IP address assigned to the workstation

单项选择题Asecondnetworkcardinaserverthatactivatesiftheprimarycardfailsisanexampleofwhichofthefollowingnetworkperformanceoptimization？（）

A.Load balancing
B.QoS
C.High availability
D.Fault tolerance

单项选择题Routingconvergencetimeiswhichofthefollowing？（）

A.Time required for a VPN connection to occur
B.Time required by protocols to update their forwarding tables after changes have occurred
C.Time required for an IDS to detect suspicious software
D.Time required by switch ports to update their link status and transition to the forwarding state