假设两台主机使用 TCP 连接传输一个大文件。下列关于 TCP 连接的哪些陈述是错误的?
1. If the sequence number of a segment is m, then the sequence
number of the subsequent segment is always m+1.
2. If the estimated round trip time at any given point of time
is t sec, the value of the retransmission timeout is always
set to greater than or equal to t sec.
3. The size of the advertised window never changes during the
course of the TCP connection.
4. The number of unacknowledged bytes at the sender is always
less than or equal to the advertised window (A)仅 3 个
(B)仅 1 和 3
(C)仅 1 和 4
(D)仅 2 和 4答案：(乙)
说明：段的 TCP 序列号是段中第一个字节的字节数。例如，如果段包含从 1000 到 1499 的 500 个字节，则该段的序列号将为 1000，下一个段的序列号将为 1500。
当接收端的应用层处理 TCP 数据时，接收窗口会发生变化。
这个问题的测验