Networking: A Beginner's Guide
ou don't need to have a Ph.D. in computer science to be an effective
networking person, but you do need to understand some rudiments of the
subject. This chapter discusses basic computer terminology and knowledge
that you should possess to make the information in the rest of the book more useful
If you've been working with computers for a while, and especially if you have
training or experience as a computer programmer, you might not need to read this
chapter in detail. However, it is a good idea to at least skim it, to make sure that you
understand these subjects thoroughly.
Bits, Nibbles, and Bytes
Most people know that computers, at their most fundamental level, work entirely using
only 1s and 0s for numbers. Each of these numbers (whether it is a 0 or 1) is called a
bit, which is short for binary digit. String eight bits together, and you have a byte; string
about 1,000 bits together, and you have a kilobit; or you can string about 1,000 bytes
together for a kilobyte. A rarely used unit is composed of four bits strung together, called
a nibble. Remember this for when you play Jeopardy!
Understanding Binary Numbers
Before you learn about binary numbers, it's useful to recall a few things about the
numbering system that people use on a daily basis. This is called the decimal numbering
system or, alternatively, the base-10 numbering system. The decimal numbering system is
built using ten different symbols, each of which represents a quantity from zero to nine.
Therefore, ten possible digits can be used: 0 through 9. (The base-10 numbering system
gets its name from the fact that only ten digits are possible in the system.)
An important part of any numbering system is the use of positions in which the
numerical symbols can be placed. Each position confers a different quantity to the
number being represented in that position. Therefore, the number 10 in the decimal
system represents the quantity ten. There is a 1 in the tens position and a 0 in the ones
position. This can also be represented as (1×10) + (0×1). Now consider the number 541.
This number uses the hundreds position as well as the tens and ones positions. It can be
represented as (5×100) + (4×10) + (1×1). In English, you could state this number as five
hundred plus forty plus one.
Every written number has a least-significant digit and a most-significant digit. The
least-significant digit is the one farthest to the right, and the most-significant digit is
the one farthest to the left. For binary numbers, people also talk about the least- and
most-significant bits, but it's the same idea.
So far, this section has simply reviewed basic number knowledge that you learned
in grade school. What grade school probably didn't cover is the fact that basing a
numbering system on ten is completely arbitrary; there is no mathematical reason to
favor a base-10 system over any other. You can create numbering systems for any base