In the following four descriptions about the relationship between the transport layer and the network layer, which one is not correct?
A. The transport-layer protocol provides logical communication between hosts
B. The transport-layer protocol provides logical communication between processes
C. The services that a transport-layer protocol can provide are often constrained by the service model of the network-layer protocol
D. A computer network may make available multiple transport protocols
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Suppose the following three 8-bit bytes: 01010101, 01110000, 01001100. What’s the 1s complement of the sum of these 8-bit bytes?
A. 00010001
B. 11101101
C. 00010010
D. 10001000
UDP and TCP both have the fields except ____.
A. source port number
B. destination port number
C. checksum
D. receive window
If we define N to be the window size, base to be the sequence number of the oldest unacknowledged packet, and next-seq-num to be the smallest unused sequence number, then the interval [nextseqnum,base+N-1] corresponds to packet that ____.
A. can be sent immediately
B. have already been transmitted and acknowledged
C. cannot be used
D. have been sent but not yet acknowledged
Which of the following about TCP is not correct?
A. It is a connectionless protocol
B. Point-to-point protocol
C. Reliable, in-order byte steam protocol
D. Pipelined protocol
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