(1) If the route (consisting of end-hosts, routers and links) from the source to the destination is fixed, which of the four types of delay, i.e., processing delay, queue delay, transmission delay, and propagation delay, are fixed for a packet of data sent from the source? (2) For electronic mail transmission, what protocol(s) mentioned in the textbook/lecture notes can be used between the sender's and receiver's mail servers? (3) Briefly explain why UDP is considered faster than TCP. (4) Find the UDP checksum of the following three 16-bit integers. 1110 0101 1010 0110 0110 1100 0110 1001 (5) NAT (Network Address Translation) is controversial because routers should only process up to layer 3. Explain why the above statement is valid. (6) Suppose you have one-byte data 1011 0110 to send. Outline a method that can provide one-bit error correction for the data.