The Internet began in 1969, designed by the U.S. Defense Department so that research scientists could communicate. A layer which maintains, monitor and expand existing networks is known as ISP (Internet Service Provider). An ISP’s gateway generally consists of a server with a permanent connection to the Internet. The Server’s connection to the Internet is called its Internet Pipeline. A Pipeline is a special hardware used to connect an ISP’s server to the Internet. ISP pipeline bandwidths of 2GB to 10GB are quite common. Clients that log into the internet via an ISP commonly use only 33.6 Kilobyte of the ISP’s bandwidth. Occasionally a client whose data traffic is very high will use special connectivity methods (ISDN) to an ISP’s server and use between 64kbps to 128kbps of the ISP’s bandwidth.
The Internet consists of two types of computers Servers and Clients
• Computers which offer information to be read are called Servers.
• Computers that read the information offered are called Clients.
Servers run special software (Web Server software) that allows them to
• Respond to Client requests for information.
• Accept data from Clients.
COMMUNICATING ON THE INTERNET
TCP/IP is the protocol used to send data all around the Internet. TCP/IP can be divided into the two sections, (TCP) a set of communication protocols and (IP) a unique address. Every machine connected to the Internet must have an address by which it can be located on the Internet. This is called the IP address of the machine. For the Internet to function smoothly, no two machines can have the same IP address. Hence each machine connected to the Internet must have a unique IP address, which identifies that machine.
The Internet is a worldwide network of networks. An international body called InterNIC, located in the USA, is responsible for registering and assigning unique IP addresses to organizations wishing to manage networks, which will be part of the Internet. This computer is known as a Domain i.e. a place where information is available. This is a Physical Domain on the Internet.
Conceptually, a server, which has a permanent IP address (i.e. a Physical Domain), can provide
• A gateway to other computers to access the Internet
• Information for Internet clients to read
• A physical location on which several Virtual Domains can be Hosted.
In many cases, when a Web Site Provides Internet clients information to read, the site is mounted as a Virtual Domain on an Internet Server, which is its (host) Physical Domain.
Each computer that has a permanent IP address, runs Server software and offers information to clients, is considered to be a Physical Domain i.e. a place where information is available.
The Physical Domain
All Internet Servers are connected to the Internet via an Internet Gateway. An Internet gateway is usually provided by one of the global networking companies who spent enormous sums of money to set up the physical networks that circle the globe.
Registering a Virtual Domain with InerNIC
Log onto an InterNIC Server. Fill up a registration form online. Pay the two-year registration fee to InterNIC. This registers a virtual domain with InterNIC.
Detailed Registration will ask for information like Personal Details, Billing Contact Information, Technical Contact Information, and Administrative Contact Information and so on.
When a company registers a virtual domain name with InterNIC, InterNIC requires a unique IP address to be specified. The unique IP address specified, is generally the IP address of the Internet server, which will host the Virtual Domain.
InterNIC’s address is http://www.internic.net/regist.html
As the number of Domain registrations grew by leaps and bounds InterINC began segregating Domains according to the services provided by the Domain being registered. This was done by adding an extension to the Domain name. The extension to the domain name indicated the kind of service being provided by that domain.
Domain Name Extension
.edu Servers that provide Educational services.
.gov Servers that provide information about the government of a country.
.mil Servers that provide Military information.
.org Servers that provide information about the Organizations in the world.
.com Servers providing commercial services on the Internet.
ESTABLISHING CONNECTIVITY ON THE INTERNET
The protocol used to setup communications between a Client and Server on the Internet is TCP/IP (Transmission Control Protocol / Internet Protocol). TCP/IP is a connection independent protocol. TCP/IP breaks up data into datagrams and guarantees that the data is correctly received at its destination.
CLIENT IP ADDRESS
How Client IP Addresses Are Assigned
Computers that only read information offered, (i.e. Internet clients) need not necessarily have a permanent IP address. However, when logged into the Internet, a client requires a unique IP address. This IP address enables the Internet server called, to reply accurately.
The Internet Service Provider’s (ISP’s) Server via which the client connects to the Internet, temporarily assigns a unique IP address to the client.
Each time the same Client logs into an ISP’s Server, the Client will be assigned a unique but different IP address temporarily. This is the technique of dynamically assigning an IP address to a client when required.
TRANSMISSION CONTROL PROTOCOL
TCP’s main task is error checking to make sure that the right numbers of packets are received and that they are in proper order.
World Wide Web
The World Wide Web is a worldwide information service on the Internet. The World Wide Web or the Web, as it is popularly known, uses special software called a Browser (client) and TCP/IP, HTTP and a Web Server to function.
TCP/IP is the communication protocol used by the Internet and is a must for the World Wide Web to function. Hypertext Transfer Protocol or HTTP is the protocol used by the WWW service to make communication possible between a Web Server and a Web Browser.
File Transfer Protocol or FTP is not just a protocol but also a service and an application. FTP is especially useful for transferring files between different computers. FTP provides the facility to transfer files between two computers running on different operating systems such as UNIX, MS-DOS and Windows.
FTP as an Application
FTP is an application for copying files. A client application can be run on the local computer to contact the FTP server application on the remote computer.
Telnet is both a TCP/IP application and a protocol for connecting a local computer to a remote computer. The Telnet application acts as a terminal emulator. Whatever commands are typed into the local computer are sent across the network for execution by the remote computer.
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