单项选择题
A. core layer
B. Internet boundary
C. aggregation layer
D. aggregation and core layers
E. access and aggregation layers
多项选择题 WhichthreeLayer2accessdesignshavealloftheiruplinksinanactivestate？（）
单项选择题 WhichofthefollowingistrueconcerningbestdesignpracticesattheswitchedAccesslayerofthetraditionallayer2EnterpriseCampusNetwork？（）
单项选择题 WhichoftheserecommendationsismostappropriateforthecorelayerintheCiscoCampus Architecture？（）