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1.1 Computer Networks

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  • 1.1 Computer Networks

    I am starting to revise my content, and thought I might as well post the revisions here to get opinions, suggestions, and feedback in general from the community. I know very little of the history section, and made my best attempt to gather accurate information, but please correct me where I have made errors. This will be the first page of my work after the preface. I would also like to acknowledge mark1950m for providing me useful feedback which makes these revisions possible.

    Thank you for reading and any feedback you are able to provide.

    Computer Networks

    A computer network is a system of nodes, connected by communication lines, for the sharing of information and services. As it relates to computer networks, a node is a device such as a computer, mobile phone, or gaming console capable of sending or receiving data over a network.

    Within a network, nodes are either providing services to other nodes or requesting services. A node that is used to provide services is called a server. There are many different types of servers, often classified by the set of services they provide. As examples, a print server allows clients to share a printer on the network, and a file server allows clients to read from, and write to, files on a digital storage device. A node that is used to request services is called a client. Your browser, such as Firefox or Internet Explorer, is an example of a client. When you surf the web, your browser requests data, so that you can read documents, listen to music, watch videos, and play games. The process of a client requesting services and a server providing services is known as the client-server model. A network which implements the client-server model is a client-server network. In a client server network, multiple client nodes can simultaneously request services from a single server node. This relationship is illustrated in Figure 1-1.

    Networks can also be classified based on the area they cover. A local area network, or LAN, is a network of personal computers in a small area, such as an office or residence. This type of network might be used to share an office printer, family photos, or other local resources. A wide area network, or WAN is a network of computers in a large area, such as a country or the world. The Internet is the largest wide area network in existence today. The Internet connects computer networks and organizational computer facilities around the globe, using fiber-optic cables, satellites, phone lines, wireless access points, and other telecommunications media.

    The first recorded description of the Internet was in a series of memos written by J.C.R Licklider in 1962 discussing his concept of a “Galactic Network”. He envisioned a global network through which users could access data and programs from any geographic location. Then, in 1964, Leonard Kleinrock wrote a book on packet switching theory and convinced Lawrence G. Roberts of the possibility of communicating on a network using packets. To explore the concept of packet switching, in 1965 Roberts and Thomas Merrill connected a computer in Mass. to a computer in California with a low speed dial-up telephone line, thus creating the first wide area network ever built. Roberts then went to DARPA, in 1966, to further develop the concept and made plans for the ARPANET. The ARPANET started in 1969 as a wide area network with two network nodes located at UCLA and Stanford. Later, in 1974, Vint Cerf and Bob Kahn published a specification for the internetwork Transmission Control Program (TCP). The ARPANET adopted the protocol, and the term Internet came into use, for referring to networks implementing the protocol.
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