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All about internet

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1All about internet Empty All about internet Fri Jul 27, 2012 11:00 pm

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What is Internet?

Internet history and how it works.
Networks and network called the Internet originated in ARPANET and NSFNET. Internet is more than a sum of connections, of course, no one foresaw how this transformation from a military to a public network and trade will affect the way we think about information and communication.

During the 60 United States Department of Defense needed a communication network in case of nuclear attack. RAND proposed a military corporation in a centralized communications network containing nodes retea.Aceasta able to send and receive messages. Each node had its own address so that the message be sent to a node. Department of Defense for advanced projects (The Defense Department's Advanced Research Projects Agency) known as ARPA or DARPA decided to expand this network. In 1969 the first "Interface Message Processor", predecessor of today's router was installed in UCLA (University of California in Los Angeles) incite ARPANET began to expand. ARPANET includes several services that today are very important in today's Internet, such as FTP (File Transfer Protocol), remote login (TELNET) and E-mail (electronic mail). While ARPANET started to grow, companies like Xerox technology develop local networks (LAN).
Network with the most impact was Ethernet, network that allows connecting multiple computers together. The first version had a theoretical transfer rate of 3 Mbps and 10 Mbps later. ARPANET researchers began to believe it would be useful to connect LANs to the ARPANET. In order to achieve this was developed a protocol to connect different types of equipment. Thus, TCP (Transmission Control Protocol) and Internet Protocol (IP). In 1983 growth was driven by the emergence of the Internet version of the UNIX 4.2 BSD also containing TCP / IP.


How does the Internet?
To understand how the Internet should understand that the Internet is not a homogeneous entity. Is indeed a great miracle that still works. The Internet has a structure so that if you send an e-mail message to the remote neighbor must traverse hundreds of miles. Moreover, the machines that are connected have been built to communicate directly with each other. Yet the Internet works.


Internet Structure
Bridge started for all the Internet is the ISP (Internet Service Provider). An ISP can be commercial or a school or a college, university, etc.Unii users can be connected in LAN, others can access the Internet using a modem and PPP or SLIP connection .. All ISPs are connected to the Internet other ISP uri.La lowest level is connected with a local ISP ISP local.Urmatorul another level is the ISPs that connect to other ISPs outside.

Routers and TCP / IP
How your application finds its way to a website and how information finds its way, is determined by two things: routers and TCP / IP. Routers (sometimes called gateways) are similar to telecoms operators. They connect networks between them and their routing tables to determine how the information flow to and from Internet.Routerele have an IP for each connection, such as a router that has a PPP connection and two Ethernet connections should have 3 IPs . The secret to making the Internet is going TCP / IP.IP is the component that moves data packets to a network node to another.
TCP is the component that checks if the data right place.
IP is a unique number for each computer.

There are three classes of IP addresses:
Class A uses the first number to identify the network and the last 3 numbers to identify your computer.
Class B uses the first two numbers identify the network and the last two numbers to identify your computer.
Class C (most common) uses the first three numbers identify the network and only the last number to identify your computer.


IP class is closely related to the number of computers retea.Dar because it is easier to remember a name than a number of Internet uses a Domain Name.Daca router is the operator of the Internet, the Domain Name Service (DNS) is telefon.Astfel card you can send me an e-mail using the name and IP popescu_gigel@192.34.55.34 or simply popescu_gigel@yahoo.com

SLIP and PPP
The methods used to connect to the Internet using a modem are Serial Line Interface Protocol (SLIP) and Poit to Point Protocol (PPP). If your ISP allows you to use SLIP and PPP, PPP choose for me is faster and safer. SLIP is not correct but is easier to configure than the PPP.
To use one of these methods of access, ISP must offer this service. Also you must have software that supports SPLIP / PPP.


How do I connect to the Internet?
To connect to the Internet takes two things: an ISP and a way to connect to this provider. The most common method of Internet concta us was using a modem connected to a telephone line, and now, I passed by fiber optics, ie direct access to the Internet.

Connecting to the Internet using a modem
The most common method of Internet connection using a modem was connected to a phone line. Modem (modulator / DEModulator) is needed to convert digital computer signals into analog signals to be transmitted over a regular telephone line, and vice versa. Modems are available in external version and international version. External modems have their own housing, separate power supply and connects to computer via serial cable. Internal modem connects to a slot in the computer and use computer source. Alegria modem you taste more than the internal performanta.Modemurile are cheaper than external ones. External modems have a display that provides various information and can be moved easily to another computer:

HS High Speed. This Means That light is ready to use your modem speed STI Highest.
AA Auto Answer. If this light is on, it Means That your modem is ready to answer the phone.
CD Carrier Detect. This Means That your modem is connected to Another modem.
OH Off Hook. This Light Comes on When your modem connects to your phone line to dial out.
RD Receive Data. This Means That your modem is Receiving Data from the Other modem.
Send Data or SD or TD Transmit Data. That this light indicates your modem is sending data.
TR Data Transmission Ready. This Light Comes on When your modem is ready to transmit data.
MR Modem Ready / Test Mode. This Light Comes on When you turn on your modem, or ITS When it drops to a lower speed setting.


About WWW
World Wide Web (also known as WWW, W3, or simply Web) made Internet access to information for the average person to be much easier. WWW is the Internet service that has developed most in recent years (which is the most used, see table). On the Web you can find information about a recipes or how to make you a thermonuclear bomb, virtually all human knowledge are gathered there.


But what is the WWW?
Strictly speaking, the WWW is a hypertext system for access to the Internet. It is made of documents, images, sounds and links to other documents or servers. A Web document may contain links to other services such as FTP, Gopher, Archie, Telnet, etc.. a better way of looking at it see the Internet is interactive, you have a graphical interface, easy to use. You can search for information about any topic. You can find information about the latest research on artificial intelligence or read the newspaper preferred. Moreover, to access this information does not need to know specific commands or code, just a simple click to access the information.

WWW appeared in 1989 as an initiative of CERN (European Laboratory for Particle Physics). Tim Berners-Lee proposed a protocol that is used to distribute information on the physics on the Internet Protocol to be adopted by other organizations.

HTTP
The most important reason that WWW can run on different computers is HyperText Transfer Protocol (HTTP). HTTP is the standard set of commands that enable communication on the Internet.
Without the browser you are using HTTP would not know if that income is HTML information or document, a program or VRML environment.

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