单项选择题
A. user EXEC mode
B. global configuration mode
C. privileged EXEC mode
D. auxiliary setup mode
单项选择题 Which statement about vlan operation on cisco catalyst switches is true?（）
单项选择题 A router receives information about network 192.168.10.0/24 from multiple sources.What will the router consider the most reliable information about the path to that network?（）
单项选择题 A receiving host computes the checksum on a frame and determines that the frame is damaged.The frame is then discarded.At which OSI layer did this happen?（）