单项选择题
Layer 3 （the network layer） provides connectivity and path selection between two host systems that may be located on geographically separated networks. Which two devices operate at the network layer？（）
A. application B. hub C. switch D. bridge E. router
单项选择题 WhatistheprimarypurposeofSMBSmartDesigns？（）
多项选择题 TheCiscoSA500SeriesSecurityAppliancesarebuiltspecificallyforbusinesseswithlessthan100employees.Whatarethreeimportantbenefitsofthisdevice？（）
单项选择题 WhichcombinationofportsisavailableontheCiscoSPA8800voicegateway？（）
