The Internet was the result of some visionary thinking by people in the early 1960s who saw great potential value in allowing computers to share information on research and development in scientific and military fields. J.C.R. Licklider of MIT, first proposed a global network of computers in 1962, and moved over to the Defense Advanced Research Projects Agency (DARPA) in late 1962 to head the work to develop it. Leonard Kleinrock of MIT and later UCLA developed the theory of packet switching, which was to form the basis of Internet connections. Lawrence Roberts of MIT connected a Massachusetts computer with a California computer in 1965 over dial-up telephone lines. It showed the feasibility of wide area networking, but also showed that the telephone line's circuit switching was inadequate. Kleinrock's packet switching theory was confirmed. Roberts moved over to DARPA in 1966 and developed his plan for ARPANET. These visionaries and many more left unnamed here are the real founders of the Internet.
Started as ARPANET which was a large wide-area network created by the United States Defense Advanced Research Project Agency (ARPA). Established in 1969, ARPANET served as a tested for new networking technologies, linking many universities and research centers. The first two nodes that formed the ARPANET were UCLA and the Stanford Research Institute, followed shortly thereafter by the University of Utah.
Now The Internet is a worldwide, publicly accessible series of interconnected computer networks that transmit data by packet switching using the standard Internet Protocol (IP). It is a "network of networks" that consists of millions of smaller domestic, academic, business, and government networks, which together carry various information and services, such as electronic mail, online chat, file transfer, and the interlinked web pages and other resources of the World Wide Web (WWW).
The communication over the interne user TCP/IP protocols
TCP (Transmission Control Protocol)
IP (Internet Protocol)
The internet has main componets which are; Host is a computer or end system at network or Internet includes PCs, workstations, servers, mainframes and so on
Ansd Network: is a group of computer within local area network (LAN) or wide area network (WAN)
Also Internet has routers: A router is a device that extracts the destination of a packet it receives, selects the best path to that destination, and forwards data packets to the next device along this path. They connect networks together; a LAN to a WAN for example, to access the Internet. Some units
The internet in the begaining has provided two main application whci are Telnet and File transfer application; FTP
IP address is a unique numeric address of the destination host or Internet address, numerical address which indicates a particular computer within a network; host name maps on IP
The internet browsers used to use Mosaic as the first graphically browser developed at NCSA Center at the University of Illinois before moving to Internet explorer or Netscape Navigator
The programming language uses to display web pages is HTML (Hyper Text Markup Language)
Also I know now about
NAP (Network Access Point)
In the United State; is one of the several major Internet interconnection points that serve ties all the ISPs together originally four NAPs
NSP (Network Service Procider)
Is a company that provides backbone services to an Internet Service Provider (ISP) connects at a point called an Internet exchange (IX) to a regional ISP that in turn connects to an NSP backbone
Internet Domain refers to a group of hosts that are under the administrative control for a single entity, such as a company or government agency. Domains are organized hieratically so that the given domain may consist of a number of subordinate domains
Domain Name System is a directory lookup service that provides a mapping between the name of a host on Internet and its numeric address. DNS is essential of the functioning of the Internet
The four major components of the domain name system are
- Domain Name Space
- DNS Database
- Name Servers
- Resolvers
Name Servers: These are server programs that hold information about a portion of the domain name tree structure and the associated PRs
Resolvers: These are programs that extract information from the servers in response to client requests. A typical client request is for an IP address corresponding to given domain name
The Internet's architecture is described in its name, a short from of the compound word "inter-networking". This architecture is based in the very specification of the standard TCP/IP protocol, designed to connect any two networks which may be very different in internal hardware, software, and technical design. Once two networks are interconnected, communication with TCP/IP is enabled end-to-end, so that any node on the Internet has the near magical ability to communicate with any other no matter where they are. This openness of design has enabled the Internet architecture to grow to a global scale.
TCP/IP protocols map to a four-layer conceptual model known as the DARPA model , named after the U.S. government agency that initially developed TCP/IP. The four layers of the DARPA model are: Application, Transport, Internet, and Network Interface. Each layer in the DARPA model corresponds to one or more layers of the seven-layer Open Systems Interconnection (OSI) model.
The network access layer is concerned with the exchange of data between a computer and a network to which it is attached. The mechanisms for providing reliability are essentially independent of the nature of applications. Thus, it makes sense to collect mechanisms in common layer shared by all applications. Protocol is a set of rules governing communication within and between computing endpoints
TCP/IP Protocol for controlling Internet communications, package of protocols which regulate connections between computers and the Internet
TCP/IP Every entity in the overall system must have a unique address. In fact two levels of addressing are needed. Each host on a network must have a unique global internet address; this allows the data to be delivered to the proper host. This address is used by IP for routing and delivery. Each application within a host must have an address that is unique within the host. This allows thebhost-to-host protocol (TCP) to deliver data to the proper process
SMTP is the Internet protocol used to transfer electronic mail between computers, much like HTTP is the Internet protocol used to transfer web pages between computers. Like HTTP, there has been more than one generation of SMTP; the second generation is called ESMTP (for Extended SMTP), but the differences are not important for this introduction.
This attempts to be a quick overview of SMTP and related concepts, explaining enough of how it works so that the reader can follow reasonable technical discussions.
In SMTP (and in the rest of this discussion), the client is the computer that is sending email, and the server is the computer that is receiving it. Thus we say SMTP clients (or SMTP senders) send email to SMTP servers, although the machines involved may both be servers in the general sense; for example an ISP's mail server sending email to the SMTP servers for utoronto.ca.
The envelope versus the letter
Just like physical letters, SMTP email has two different sets of address information: the envelope headers, like the addresses on the outside of an envelope, which are used by mail transport software to route and deliver the email, and the normal headers, which are part of the mail message and which are only read and interpreted by the user and his software, just like the address attached to a salutation at the start of a physical letter. Unlike the post office, SMTP usually throws away most of the envelope before it hands the message to the user, so many users are not aware of the envelope headers.
In fact, SMTP never looks at the message headers at all; as far as SMTP is concerned, the email message (headers and all) is just one big blob that it shuttles around. Many SMTP clients are perfectly happy to deliver email with badly broken or entirely nonexistent message headers.
The SMTP protocol
Like many Internet protocols, SMTP operates by sending lines of text back and forth between the client and the server. The client sends commands and eventually the email message, and the server sends back responses to tell the client if the server accepted the command or if something went wrong.
Web cashing is when a browser makes an initial request to a web site - for example, a GET request for a home page - the server normally returns a 200 OK Response Code and the home page. Additionally, the server will return a 200 OK response and the specified object for each of the dependent resources referenced in that page, such as graphics, style sheets, and JavaScript files. Without appropriate freshness headers, a subsequent request for this home page will result in a "conditional" GET request for each resource. This conditional GET validates the freshness of the resource using whatever means it has available for comparison, usually the Last-Modified timestamp for the resource (if Last-Modified is not available, such as with dynamic files, an unconditional GET will be sent that circumvents caching altogether). Through a roundtrip to the server, it will be determined whether the Last-Modified value of the item on the server matches that of the item cached in the browser, and either a fresh version will be returned from the server with a 200 OK response, or a 304 Not-Modified response header will be returned, indicating that the file in the cache is valid and can be used again.
Client/Server Applications: Cooperating applications can be categorized as either a client or a server. The client application requests services and data from the server, and the server application responds to client requests. Early two-tier (client/server) applications were developed to access large databases, and incorporated the rules used to manipulate the data with the user interface into the client application. The server's task was simply to process as many requests for data storage and retrieval as possible.
