【名词&注释】
有效性(effectiveness)、准备工作(preparation work)、工程施工(engineering construction)、承包人(contractor)、高速缓存(cache)、回收站(recycle bin)、安全门(safety door)、天气现象(weather phenomena)、每一个(every single)、重新开始(restart)
[单选题]When the system upon which a transport entity is running fails and subsequently restarts,the(21) information of all active connections is lost. The affected connections become half-open, as the side that did not fail does not yet realize the problem.The still active side of a half-open connections can close the connection using a(22)timer. This timer measures the time the transport machine will continue to await an (23) of a transmitted segment after the segment has been retransmitted the maximum number of times.When the timer (24),the transport entity assumes that either the other transport entity or the intervening network has failed. As a result, the timer closes the connection, and signals an abnormal close to the TS user. In the event that a transport entity fails and quickly restarts, half-open connections can be terminated more quickly by the use of the RST segment, the failed side returns an RST i to every segment i that it receives. When the RST i reaches the other side, it must be checked for validity based on the (25) number i, as the RST could be in response to an old segment. If the reset is valid, the transport entity performs an abnormal termination.
A. C