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Internet:
Internet is a network of networks. The Internet is a global system of interconnected computer networks that use the standard Internet Protocol Suite (TCP/IP) to serve billions of users worldwide.
Intranet:
An intranet is a private computer network that uses Internet Protocol technologies to securely share any part of an organization's information or operational systems within that organization.
Extranet
An extranet is a private network that uses Internet protocols, network connectivity. An extranet can be viewed as part of a company's intranet that is extended to users outside the company, usually via the Internet.
ARPANET
The precursor to the Internet, ARPANET 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 (University of California, Los Angeles) and the Stanford Research Institute, followed shortly thereafter by the University of Utah.
ARPANET completed its transition to TCP/IP on January 2, 1983, was later replaced by NSFNET in 1990, and then decommissioned on February 28, 1990.
Network
A network is defined as a group of two or more computer systems linked together. There are many types of computer networks, including the following:
Local-Area Networks (LANs): The computers are geographically close together (that is, in the same building).
Wide-Area Networks (WANs): The computers are farther apart and are connected by telephone lines or radio waves.
Campus-Area Networks (CANs): The computers are within a limited geographic area, such as a campus or military base.
Metropolitan-Area Networks MANs): A data network designed for a town or city.
Home-Area Networks (HANs): A network contained within a user's home that connects a person's digital devices.
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Topology: The geometric arrangement of a computer system. Common topologies include a bus, star, and ring.
Architecture: Networks can be broadly classified as using either a peer-to-peer or client/server architecture.
Node: Computers on a network are sometimes called nodes.
Server: Computers and devices that allocate resources for a network are called servers.
Protocol: The protocol defines a common set of rules and signals that computers on the network use to communicate. One of the most popular protocols for LANs is called Ethernet. Another popular LAN protocol for PCs is the IBM token-ring network.
Types of Protocol:
Stateful (TCP)
Stateless (IP, HTTP)
A stateless protocol does not require the server to retain session information or status about each communications partner for the duration of multiple requests. In contrast, a protocol which requires keeping of the internal state on the server is known as a stateful protocol.
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TCP - A reliable connection oriented protocol used to control the management of application level services between computers. IP - Internet Protocol (IP). Provides the mechanism to use software to address and manage data packets being sent to computers. UDP - An unreliable connection less protocol used to control the management of application level services between computers. SMTP - Simple Mail Transfer Protocol (SMTP). FTP - File Transfer Protocol (FTP). Allows file transfer between two computers with login required. Telnet - A method of opening a user session on a remote host. Ping - A program that uses ICMP to send diagnostic messages to other computers to tell if they are reachable over the network. PPP - Point to point protocol (PPP). A form of serial line data encapsulation that is an improvement over SLIP. ARP - Address resolution protocol (ARP) enables the packaging of IP data into Ethernet packages. ICMP - Internet control message protocol (ICMP) provides management and error reporting to help manage the process of sending data between computers. DNS - Domain Name Service allows the network to determine IP addresses from names and vice versa. IGMP - Internet Group Management Protocol used to support multicasting. RIP - Routing Information Protocol (RIP), used to dynamically update router tables on WANs or the internet. Ethernet - Ethernet is a link layer protocol in the TCP/IP stack, describing how networked devices can format data for transmission to other network devices on the same network segment, and how to put that data out on the network connection.
LocalTalk - LocalTalk is a particular implementation of the physical layer of the AppleTalk networking system from Apple Computer. LocalTalk specifies a system of shielded twisted pair cabling, plugged into self-terminating transceivers.
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ATM (Asynchronous Transfer Mode) is a dedicated-connection switching technology that organizes digital data into 53-byte cell units and transmits them over a physical medium using digital signal technology.
POP - Post Office Protocol (POP) is an application-layer Internet standard protocol used by local e-mail clients to retrieve e-mail from a remote server over a TCP/IP connection.
HTTP - HTTP (Hypertext Transfer Protocol) is the set of rules for transferring files (text, graphic images, sound, video, and other multimedia files) on the World Wide Web.
HTTPS - Hyper Text Transfer Protocol Secure (HTTPS) is the secure version of HTTP, the protocol over which data is sent between your browser and the website that you are connected to. The 'S' at the end of HTTPS stands for 'Secure'. It means all communications between your browser and the website are encrypted. HTTPS is often used to protect highly confidential online transactions like online banking and online shopping order forms.
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