单项选择题
A. NBAR examines data in Layers 1 and 4.
B. NBAR examines data in Layers 3 and 4.
C. NetFlow examines data in Layers 3 and 4.
D. NBAR examines data in Layers 2 through 4.
单项选择题 Whichsite-to-siteVPNsolutionallowsCiscorouters，PIXFirewalls，andCiscohardwareclientstoactasremoteVPNclientsinordertoreceivepredefinedsecuritypoliciesandconfigurationparametersfromtheVPNheadendatthecentralsite？（）
单项选择题 WhyisSTPrequiredwhenVLANsspanaccesslayerswitches？（）
单项选择题 InaVoWLANdeployment，whatistherecommendedseparationbetweencellswiththesamechannel？（）