Chapter 7. The Application Layer

Having finished all the preliminaries, we now come to the layer where all the applications are found. The layers below the application layer are there to provide reliable transport, but they do not do real work for users. In this chapter we will study some real network applications.

However, even in the application layer there is a need for support protocols, to allow the applications to function. Accordingly, we will look at one of these before starting with the applications themselves. The item in question is DNS, which handles naming within the Internet. After that, we will examine three real applications: electronic mail, the World Wide Web, and finally, multimedia.

DNS—The Domain Name System

Although programs ...

Get Computer Networks, Fourth Edition now with the O’Reilly learning platform.

O’Reilly members experience books, live events, courses curated by job role, and more from O’Reilly and nearly 200 top publishers.