●The TCP protocolis a (71) layer protocol. Each connection connects two TCPs that may be just one physical network apart or located on opposite sides ofthe globe. In other words, each connection creates a (72) witha length that may be totally different from another path created by another connection. This means that TCP cannot use the same retransmission time for all connections. Selecting afixed retransnussion time for all connections can result in serious consequences. Ifthe retransmission time does not allow enough time for a (73) to reach the destination and an acknowledgment to reach the source, it can result in retransmission of segments that are still on the way. Conversely, if the retransnussion time is longer than necessary for a short path, it may result in delay for the application programs.
Even for one single connection, the retransmission time should not be fixed.A connection may be able to send segments and receive (74)faster during nontraffic period than during congested periods. TCP uses the dynamic retransmission time,a transmission time is different for each connection and which may be changed during the same connection. Retransmission time can be made(75) by basing it on the round-trip time (RTT). Several formulas are used for this purpose.
(71) A.physical
B.network
C.transport
D.application
(72) A.path
B.window
C.response
D.process
(73) A.process
B.segment
C.program
D.user
(74) A.connections
B.requests
C.acknowledgments
D.datagrams
(75) A.long
B.short
C.fixed
D.dynamic
第1题:
Acknowledgements, sequencing, and flow control are functions that are handled by which layer of the OSI model?
A. Layer 5
B. Layer 4
C. Layer 7
D. Layer 6
E. Layer 3
F. Layer 2
G. Layer 1
第2题:
以下程序段的输出结果为( )。 int j=2 switch (j){ Case 2: system.out.print("two."): Case 2+1: System.out.println("three."); break: default: System.out.println (“value is”+j): Break }A.B.two
A.two.three.
B.two
C.three
D.value is 2
第3题:
第4题:
● TCP/IP communication protocol contains four layers. From bottom to top, the four layers are __(71)__.
(71)A.network interface layer, internet layer, transport layer and application layer
B.internet layer, network interface layer, transport layer and application layer
C.network interface layer, transport layer, network interface layer and application layer
D.application layer, transport layer, internet layer and network interface layer
第5题:
A. Layer 2
B. Layer 3
C. Layer 4
D. Layer 5
E. Layer 6
F. Layer 7
第6题: