Networks and the Internet

A computer network:

is a collection of computers and other devices all communicating with one another. It is composed of computers, peripheral and networking devices, communication medium, and networking software.

A computer capable of sending or receiving data from a computer network is said to be online to the network otherwise it is offline.

Benefits of using Networks :
Reduce cost.
Facilitate person-to-person communication.
Enhance a company’s work performance.

A username, user ID, or login ID and a pass­word are usually required to log on to a network.

Network Topologies
Basic Types of Network Topologies:
is the way computers and other network devices are physically linked together or interconnected.

Network Architectures

Client-Server Architecture

File Server
Print server
Mail server and Web Server
Network servers

With a P2P network:

All the computers on the network work at the same level.
Users have direct access to the other computers and the peripherals attached to the network.

Internetworking

Internetworking: is the process of connecting two or more networks.

Connecting two or more networks create an internet.

 A MAN or WAN that is constructed by internetworking several LANs can be seen as an internet.
 The Internet with uppercase I is a specific worldwide internet.

The World Wide Web or WWW: is a collection of millions of documents that are accessible through the Internet and that are stored and distributed on millions of computers worldwide.

 A WWW document is referred to as a Web page.


Intranets and Extranets

An intranet is a private network set up like the Internet with data posted to Web pages that are accessed via a Web browser.

An extranet is an intranet that is at least partially accessible to authorized outsiders.

Extranets can be used to provide customers and business partners with access to the data they need.

A virtual private network or VPN: is a private, secure path across a public communica­tion network as the Internet.

A VPN is set up to allow authorized users private, secure access to a company network without the need to pay too much money for extending the network.