单选题A ( )is a set of rules that controls the interaction of different devices in a network or internetwork.
A. model
B. protocol
C. dialog
D. synchronization point
单选题 The OSI model has ( ) layers.
A. five
B. six
C. seven
D. any of the above
单选题 The ( )layer of the OSI model organizes bits into logical data units called frames.
A. physical
B. data-link
C. network
D. transport
单选题 The ( ) layer of the OSI model enables a person to access the network.
A. data-link
B. transport
C. application
D. physical