Understanding Networks

[ What is a Network? | History of the Internet | DNS | TCP/IP | PPP | Segments of the Internet ]

 

The Internet works like a Local Area Network or LAN, just on a much larger scale. If you understand how LANs work, you already have a good understanding of how the Internet works.

In its simplest form, a network is made of clients and servers linked together so that they can share information.

A server is the computer responsible for sending information to the clients. Internet servers that users can log on to are known as hosts.

Computers that are connected to the server are called clients. When a client requests a resource (e.g. a file), the request goes to the server, which then finds the requested file and then sends it back to the client. The client then runs the application that uses the requested file.

The Internet is a global network of networks.

Computers attached to a network, including the Internet, are able to share files and other resources.

Connectivity across the Internet is made possible because of a common language and communications protocol which works with most personal computers.

History of the Internet

In 1969, the U.S. Department of defense established the Advanced Research Projects Agency Network (ARPANET). Its purpose was to allow researchers and military personnel to share information and research data. The idea was that if sections of the network were disabled in the event of a natural disaster or nuclear attack, the flow of information could continue along functioning sections of the network.

In the 1980s, the National Science Foundation established a system of high-speed phone lines so researchers in remote areas could have access to their computing resources. This communication backbone was called NFSNET. ARPANET was eventually absorbed into NFSNET. Soon every major university and government agency added their networks to the growing whole.

The Domain Name System

The domain name system is used to find internet hosts and the main function of that host (web, ftp, or e-mail server). It is very similar to the your telephone number which tells you country, area code and the actual phone number.

An Internet address or IP address as it is commonly called, is made up of a four part series of numbers. The domain name system takes the numbers and translates them into a user-friendly system of text based names. So rather than typing in 128.337.392.449 to order a pepperoni pizza over the Internet, you can simply type in www.pizzahut.com which is much easier to remember.

Reading from left to right, a domain name describes the following: the client name (user name), the local server name (the name of the local network the client belongs to), the sub-domain (initials of a university, for example), and the internet domain.

Domain Extension	Used By
.com	commercial businesses
.gov	government agencies
.edu	educational institutions
.org	various organizations
.mil	military
.net	network resources

TCP
The communications protocol used for Internet connections is TCP/IP (Transmission Control Protocol/Internet Protocol). In actuality, it is a suite of protocols, working together, which make the Internet work. TCP/IP enables remote logins, routes data between hosts, makes sure data packets are error free and assembled in the correct sequence and converts text-based domain names into IP addresses

PPP
PPP (point to point protocol) connects your computer to the Internet via a dial-up telephone line. PPP lets your PC act like an Internet machine. To use PPP, both the host and your computer must be running PPP. If you are using Windows 95/98, the dial up net working adapter is PPP compatible.

 

Segments of the Internet

 

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