多项选择题 The network administrator of the Oregon router adds the following command to the router configuration: ip route 192.168.12.0 255.255.255.0 172.16.12.1. What are the results of adding this command (Choose two.)（）。

单项选择题 Areceivinghostcomputesthechecksumonaframeanddeterminesthattheframeisdamaged.Theframeisthendiscarded.AtwhichOSIlayerdidthishappen？（）

多项选择题 Which two benefits are provided by creating VLANs? （）