Internet: Internet is the medium of communication. Internet consists of an incredible number of participates, connected machines, software programs and a massive quantity of information spread all around the world. Advanced Research Projects Administration NET is the ancestor of the Internet.
A network is a set of computers interconnected by the transmission paths to exchange information. Networks are in two-way communication.
Network topology: Network topology is the representation of physical connectives of the computers.
1) Hierarchical topology (vertical or tree network)
2) Horizontal Topology (Bus Topology)
In case main communication channel fails, the entire network crashes. It is used in LAN.
3) Star topology
It is easy to identify the faults points by isolating the lines.
4) Ring topology
Data flow is in one direction only. If the channel between two nodes fails, the network is lost.
Types of networks:
1) LAN (local Area Network)
Â¢ It uses broadcast channels for communication.
Â¢ Covers an area not more then few kms.
Â¢ Data rate is several Mbps
Â¢ Owned by a single organization.
2) WAN (Wide Area Network)
Â¢ Uses point to point links
Â¢ Spans an entire country.
Â¢ Data rate <1Mbps
Â¢ Can be owned by a single organization
3) Man (Metropolitan Area Network)
Â¢ Lies in between LAN and WAN technology.
The data is transmitted in the form of digital signals. These signals are converted into a form suitable analog transmission (modulation). The process of transforming the analog signal into digital at the receiving end is called demodulation. The device used for this purpose is called modem.
Two ways of connection are
Â¢ Dedicated access: we can access the Internet directly computer remains connected to the Internet throughout the day.
Â¢ Dial up access: the computer is connected to net by means of modem.
E-mail: it is an electronic form of regular mail. The ISP (Internet services provider) delivers the message conveyed in the e-mail to the required person. It is very easy to use, fast, and cheaper than sending regular e-mail. The ISP is a company that offers a connection to the Internet via an Internet account. The following is a list of all major mail and on-line systems that are connected to the net Apple link, AT&T mail BITNET, BIX and Delphi. ISP are listed below: CompuServe, America Online, MSN, UNIX shell providers
Internet is the network of networks. It is a network of computers communicating with each other over fiber optic cables, telephone lines, satellite links and other media. Technically speaking, the internet is a network formed by the co-operative interconnection of various computing networks. In fact, the word Internet was coined from the words "interconnection" and "network".
History Of Internet:
The Internet has revolutionized the computer and communications world like nothing before. The invention of the telegraph, telephone, radio, and computer, set the stage for this unprecedented integration of capabilities. The Internet is a world-wide broadcasting capability, a mechanism for information dissemination, and a medium for collaboration and interaction between individuals and their computers, all in one.
The Internet is like a vast transportation system for data. The system includes and connects local, regional, national, and international networks. The Internet represents one of the most successful examples of the benefits of sustained investment and commitment to research and development of information infrastructure.