单项选择题
A.the MAC address of the seiver network interface
B.the MAC address of host A
C.the MAC address of router interface e 1
D.the MAC address of router interface e0
多项选择题 Which of the following correctly describe steps in the OSI data encapsulation process?（）
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?（）
单项选择题 A network administrator is verifying the configuration of a newly installed host by establishing an FTP connection to a remote server. What is the highest layer of the protocol stack that the nework administrator is using for this operation?（）
