Before we begin talking about specific networking technologies and applications, it’s worth taking a few
pages to go over some networking fundamentals. Networks exist for the sole purpose of sharing information
between people or machines. However, to share information, rules must be followed to ensure that
the myriad combinations of devices, transports, hardware, and software can communicate smoothly.
In “How Computers Communicate,” we cover the most basic aspects of computer networking, starting
with the OSI model. This communication model is the basis for all other topics discussed in this book, so
it’s a great place to start.
In “TCP/IP and IP Addressing,” we explore how two of the most popular protocols in use today work.
TCP/IP is the communication protocol that drives the Internet as well as most corporate traffic. We then
go a bit deeper into the Internet Protocol with a discussion of IP addressing, the concept that allows
shared information to reach its intended destination. We end the chapter with an overview of IPv6. The
addressing scheme discussed here (known as IPv4) has been in service for years. However, there has been
some concern in recent years that Internet has grown beyond the current IP addressing scheme’s ability to
serve an ever-growing demand. Changing addressing schemes this far into networking’s history provides
some interesting challenges, which we will also explore.
“Internet Applications” provides a look at two of the most common applications—e-mail and web browsing.
This chapter provides some background on how these applications came about and provides a summary
of how they work. This should be helpful, because you probably use these applications every day.