In the 1980s, when we wrote the first edition of this book, there were many, many more protocols in common use at the data link, network, and transport layers than there are today. Why do you think the number of commonly used protocols at these layers has declined? Do you think this trend will continue? What ❦ ❦ ❦ ❦ Minicases 21 are the implications for those who design and operate networks?

Select the correct answer. sean is a computer programmer. he has programmed an application for toddlers that plays nursery rhymes. however, a logic error has occurred in the program. which problem is a likely consequence of the error? a. the program crashes every time the user wants to play the nursery rhymes. b. the program crosses its buffer boundaries and overwrites an adjacent program. c. the program plays a different nursery rhyme than the one the user intended to play. d. the program shows different structures in its programming language code. e. the program introduces new viruses every time the user plays a nursery rhyme.