Both UDP and TCP header includes a checksum field, which is an important value in the transport layer. 1) Explain the function of checksum. 2) Whats the checksum for the following three 16-bit words, 1000 0110 0101 1110, 1010 1100 0110 0000, 0111 0001 0010 1010? 3) Assume that a host receives a UDP segment with 01011101 11110010 as the checksum. The host adds all necessary fields and obtains the value 00110010 00001101. Is the segment considered correctly received or not? Justify your answer. What does the receiver do? 4) Suppose that the TCP receiver computes the checksum for the received TCP segment and finds that it matches the value carried in the checksum field. Can the receiver be absolutely certain that no bit errors have occurred? Briefly explain your answer.