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(b)(4%) Suppose a computer is moved from one department to another. Does its physical address need to change? Does the IP address need to change? Why or why not? No, physical address need not change. Yes, the IP address need to be changed since all hosts on an a subnet should have the same network prefix.(c)(4%) Why do HTTP, FTP, and SMTP run on top of TCP rather than UDP? All these applications need reliable delivery and are not delay sensitive. Hence TCP is suitable for these applications. If they were implemented over UDP, then they would need to duplicate the functionality of TCP for retransmission of lost packets etc. (d)(4%) When the loss rate is high and round trip time is long, which one is better: go-back-N or selective-repeat? Why? Selective-repeat. Go-back-N retransmission waste bandwidth(e)(4%) The figure on the left shows a network with a hub. Each computer is connected to the hub with a cable of length 1000 m. Calculate the minimum frame size that can be supported so that CSMA/CD protocol will function correctly. The distance between two farthest computers = 2000 m End to end propagation delay = 10 micro-seconds Worst case collision detection time = 20 micro-seconds Minimum frame size = 200 bits = 25 bytes