Problems: 1. Give the description (i.c, definition) of the following terminologies: a) Multiplexing, b) Demultiplexing, e) Threshold, d) Slow start, e) Go-Back-N protocol. (25 pts) 2. Suppose Client W initiates a Telnet session with Server SS. At about the same time, Client Z also initiates a Telnet session with Server SS. Provide possible source and destination port numbers for: a) The segments sent from W to SS. b) The segments sent from Z to SS. c) The segments sent from SS to W. d) The segments sent from SS to Z e) If W and Z are different hosts, is it possible that the source port number in the segments from W to SS is the same as that from 2 to SS? ) How about if they are the same host? 3. Suppose you have the following four 16-bit words: 0000101010110111 0010101100101111 1000101110101101 0000101010100101 Show the UDP checksum steps in both sender and receiver sides. (25 pts) 4. Consider Fig. 1. What are the source and destination port values in the segments flowing from the server back to the clients' processes? What are the source and destination IP addresses in the network-layer datagrams carrying the transport-layer segments? w Fig 1. Two clients, using the same destination port number (80) to communicate with the same Web server application