Networking Basics

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Web browser and plug-ins

This page will explain what a Web browser is and how it performs the following functions:

Contacts a Web server
Requests information
Receives information
Displays the results on the screen

A Web browser is software that interprets HTML, which is one of the languages used to code Web page content. Some new technologies use other markup languages with more advanced features. HTML, which is the most common markup language, can display graphics or play sound, movies, and other multimedia files. Hyperlinks that are embedded in a Web page provide a quick link to another location on the same page or a different Internet address.

Two of the most popular Web browsers are Internet Explorer (IE) and Netscape Communicator. These browsers perform the same tasks. However, there are differences between them. Some websites may not support the use of one of these browsers. It is a good idea to have both programs installed.

Here are some features of Netscape Navigator:

Was the first popular browser
Uses less disk space
Displays HTML files
Performs e-mail and file transfers

Here are some features of IE:

Is powerfully integrated with other Microsoft products
Uses more disk space
Displays HTML files
Performs e-mail and file transfers

There are also many special, or proprietary, file types that standard Web browsers are not able to display. To view these files the browser must be configured to use the plug-in applications. These applications work with the browser to launch the programs required to view special files:

Flash – Plays multimedia files created by Macromedia Flash
Quicktime – Plays video files created by Apple
Real Player – Plays audio files

Use the following procedure to install the Flash plug-in:

1- Go to the Macromedia website.
2- Download the latest flash player installer file.
3- Run and install the plug-in in Netscape or IE.
4- Access the Cisco Academy website to verify the installation and proper operation.

Computers also perform many other useful tasks. Many employees use a set of applications in the form of an office suite such as Microsoft Office. Office applications typically include the following:

- Spreadsheet software contains tables that consist of columns and rows and it is often used with formulas to process and analyze data.
- Modern word processors allow users to create documents that include graphics and richly formatted text.
- Database management software is used to store, maintain, organize, sort, and filter records. A record is a collection of information identified by some common theme such as customer name.
- Presentation software is used to design and develop presentations to deliver at meetings, classes, or sales presentations.
- A personal information manager includes an e-mail utility, contact lists, a calendar, and a to-do list.


Office applications are now a part of daily work, as typewriters were before PCs.

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Network Math

Binary presentation of data

This page will explain how computers use the binary number system to represent data.

Computers work with and store data using electronic switches that are either ON or OFF. Computers can only understand and use data that is in this two-state or binary format. The 1s and 0s are used to represent the two possible states of an electronic component in a computer. 1 is represented by an ON state, and 0 is represented by an OFF state. They are referred to as binary digits or bits.

American Standard Code for Information Interchange (ASCII) is the code that is most commonly used to represent alpha-numeric data in a computer. ASCII uses binary digits to represent the symbols typed on the keyboard. When computers send ON or OFF states over a network, electrical, light, or radio waves are used to represent the 1s and 0s. Notice that each character is represented by a unique pattern of eight binary digits.

Because computers are designed to work with ON/OFF switches, binary digits and binary numbers are natural to them. Humans use the decimal number system, which is relatively simple when compared to the long series of 1s and 0s used by computers. So the computer binary numbers need to be converted to decimal numbers.

Sometimes binary numbers are converted to hexadecimal numbers. This reduces a long string of binary digits to a few hexadecimal characters. It is easier to remember and to work with hexadecimal numbers.

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Bits and bytes

This page will explain what bits and bytes are.

A binary 0 might be represented by 0 volts of electricity.

A binary 1 might be represented by +5 volts of electricity.

Computers are designed to use groupings of eight bits. This grouping of eight bits is referred to as a byte. In a computer, one byte represents a single addressable storage location. These storage locations represent a value or single character of data, such as an ASCII code. The total number of combinations of the eight switches being turned on and off is 256. The value range of a byte is from 0 to 255. So a byte is an important concept to understand when working with computers and networks.

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Base 10 number system

Numbering systems consist of symbols and rules for their use. This page will discuss the most commonly used number system, which is decimal, or Base 10.

Base 10 uses the ten symbols 0, 1, 2, 3, 4, 5, 6, 7, 8, and 9. These symbols, can be combined to represent all possible numeric values.

The decimal number system is based on powers of 10. Each column position of a value, from right to left, is multiplied by the base number 10 raised to a power, which is the exponent. The power that 10 is raised to depends on its position to the left of the decimal point. When a decimal number is read from right to left, the first or rightmost position represents 100, which equals 1. The second position represents 101, which equals 10. The third position represents 102, which equals 100. The seventh position to the left represents 106, which equals 1,000,000. This is true no matter how many columns the number has.

Here is an example:

2134 =
(2x10^3) + (1x10^2) + (3x10^1) + (4x10^0)

This review of the decimal system will help you understand the Base 2 and Base 16 number systems. These systems use the same methods as the decimal system.

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Base 2 number system


This page will discuss the number system that computers use to recognize and process data, which is binary, or Base 2.
The binary system uses only two symbols, which are 0 and 1. The position of each digit from right to left in a binary number represents the base number 2 raised to a power or exponent. These place values are, from right to left, 20, 21, 22, 23, 24, 25, 26, and 27, or 1, 2, 4, 8, 16, 32, 64, and 128 respectively.

Here is an example:

101102 =
(1 x 2^4 = 16) + (0 x 2^3 = 0) + (1 x 2^2 = 4) + (1 x 2^1 = 2) + (0 x 2^0 = 0) = 22 (16 + 0 + 4 + 2 + 0)

This example shows that the binary number 10110 is equal to the decimal number 22.

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Converting decimal numbers to 8-bit binary numbers


This page will teach you how to convert decimal numbers to binary numbers.


Conversion exercise:

Use the example below to convert the decimal number 168 to a binary number:

128 is less than 168 so the left most bit in the binary number is a 1. 168 - 128 = 40.
64 is not less than or equal to 40 so the second bit from the left is a 0.
32 is less than 40 so the third bit from the left is a 1. 40 - 32 = 8.
16 is not less than or equal to 8 so the fourth bit from the left is a 0.
8 is equal to 8 so the fifth bit from the left is a 1. 8 - 8 = 0. Therefore, the bits to the right are all 0.

This example shows that the decimal number 168 is equal to the binary number 10101000.

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Converting 8-bit binary numbers to decimal numbers

This page will teach you how to convert binary numbers to decimal numbers.

Here is an example:

Convert the binary number 01110000 to a decimal number.


NOTE:
Work from right to left. Remember that anything raised to the 0 power is 1.

0 x 20 = 0

0 x 2^1 = 0

0 x 2^2 = 0

0 x 2^3 = 0

1 x 2^4 = 16

1 x 2^5 = 32

1 x 2^6 = 64

0 x 2^7 = 0

__________

= 112