Internet堆栈中应用层的协议数据单元(PDU)为
(A)细分
(B)数据报
(C)留言
(D)框架答案： (C)
说明：协议数据单元是特定层上的通信单元。
The Layer 1 (Physical Layer) PDU is the bit or, more generally, symbol
The Layer 2 (Data Link Layer) PDU is the frame.
The Layer 3 (Network Layer) PDU is the packet.
The Layer 4 (Transport Layer) PDU is the segment
for TCP or the datagram for UDP.
The Layer 5 (Application Layer) PDU is the data or message.
这个问题的测验