学员提问：
45. Which of the following correctly describe steps in the OSI data encapsulation process? (Choose two.)
A. The transport layer divides a data stream into segments and may add reliability and flow control
information.
B. The data link layer adds physical source and destination addresses and an FCS to the segment.
C. Packets are created when the network layer encapsulates a frame with source and destination host
addresses and protocol-related control information.
D. Packets are created when the network layer adds Layer 3 addresses and control information to a
segment.
E. The presentation layer translates bits into voltages for transmission across the physical link.
这题要选什么？
捷盈讲师及学员解答：
C，网络层封装的是packet而不是frame。