Why does UDP exist? Would it not have been enough to just let user processes and send raw IP packets?

Dr. wisteria is a prominent chiropractor in the chicago area. she wants to provide a forum for her patients to discuss their health concerns and to seek and offer advice to other patients. which telecommunications tool is most appropriate for dr. wisteria's needs?

Avariable definition defines the name of a variable that will be used in a program, as well as

Write a program that asks the user to enter the name of an input file. if the file does not exist, the program should prompt the user to enter the file name again. if the user types quit in any uppercase/lowercase combinations, then the program should exit without any further output.