Consider a TCP connection where the last acknowledgement sent by the TCP receiver has the following fields: ACK=21000, WIN=4000, Which of the following is not a valid segment that the sender can transmit given this scenario?
a) Sender can transmit a 1000 byte segment with sequence number=21000
b) Sender can transmit a 2000 byte segment with sequence number=22100
c) Sender can transmit a 1500 byte segment with sequence number=21500
a) Sender can transmit a 3000 byte segment with sequence number=23000
