Networking and the Internet

• LAN: (Local Area Network) consists of a series of computers linked together to form a network in a circumscribed location, connected to each other via TCP/IP ethernet or Wi-Fi.
• MAN: (Metropolitan Area Network) a network that connects computers within a metropolitan area.
• WAN: (Wide Area Network)a network that connects smaller networks (LANs) across great distances.

• bus network: a LAN topology in which each node - a workstation or other device - is connected to a main cable or link called a bus.
• star network: a LAN topology in which all nodes - personal computers, workstations, or other devices - are directly connected to a common central computer that is often referred to as a hub.

• CSMA/CD Ethernet: a media access control method that was widely used in Early Ethernet technology when there used to be shared Bus Topology and each node were connected by coaxial cables.
• CSMA/CA Wifi: a protocol for carrier transmission in 802.11 networks. It was developed to minimize the potential of a collision occuring when two or more stations send their signals over a data link layer.

• repeater: a powerful network hardware device that regenerates an incoming signal from the sender before retransmitting it to the receiver.
• bridge: a class of network device designed to connect networks at Open Systems Interconnection (OSI) Level 2.
• switch: a device that channels incoming data from any multiple input ports to the specific output port that will take the data toward its intended destination.
• router: a physical/virtual appliance that passes information between two or more packet-switched computer networks.
• gateway: a computer that sits between different networks or applications.

• P2P (peer-to-peer): a group of computers that are linked together with equal permissions and responsibilities for processing data.
• distributed system: any environment where multiple computers or devices are working on a variety of tasks and components, all spread across a network.
• cloud computing: the delivery of computing services over the internet to offer faster innovation, flexible resources, and economies of scale.

• Tier 1: the networks that are the backbone of the Internet. They build infrastructure such as the Atlantic Internet sea cables and they provide traffic to all other ISPs.
• Tier 2: a service provider that utilizes a combination of paid transit via Tier 1 ISPs and peering with other Tier 2 ISPs to deliver Internet traffic to end customers through Tier 3 ISPs.
• Tier 3: a provider that strictly purchases Internet transit; primarily engaged in delivering Internet access to end customers.

• ICANN: a nonprofit organization headquartered in Southern California, formed to help the U.S. government manage certain functions that mantain the Internet's core infrastructure.
• DNS: (Domain Name System) turns domain names into IP addresses, which broswers use to load internet pages.
• TLD (Top-level domain): describes the part of the URL that represents the final section of a domain name (Ex. .com, .gov, .edu)
• Country-code TLDs: an Internet top-level domain generally used or reserved for a country (usually 2 letters long).

• FTP: (File Transfer Protocol) a standard network protocol used for the transfer of files from one host to another over a TCP-based network, such as the Internet.
• HTTP: (Hypertext Transfer Protocol) a networking protocol for distributed, collaborative, hypermedia information systems.
• SMTP: (Simple Mail Transfer Protocol) a TCP/IP protocol used in sending and receiving email.

• URL: (Uniform Resource Locator) the address of a given unique resource on the Web.
• client-side activities: everything in a web application that is displayed or takes place on the client (end user device).
• server-side activites: everything that happens on the server, instead of on the client.

• application layer: the level at which the information reaches the programs in which we can read it.
• transport layer: functions as the information sending route, since it will provide the reliable connection that devices need to send information to each other.
• network layer: provides the functional and procedural means of transferring variable length data sequences from a source host on one network to a destination host on a different network, while maintaining the quality of service requested by the trasport layer.
• link layer: the information transfer reaches the components of the devices that make Internet access possible.

• packet-switching network: The Internet transfers small pieces of data across various networks.
• fault tolerant: The Internet has the ability to continue operating uniterrupted despite the failure of one or more of its components.
• redundant: Redundancy is the proccess of providing multiple paths for traffic so that the data can keep flowing even in the event of a failure.

• malware: a file or code that infects, explores, steals, or conducts virtually any behavior an attacker wants.
• virus: A computer program that can copy itself and infect a computer without permission or knowledge of the user.
• worm: a type of malware whose primary function is to self-replicate and infect other computers while remaining active on infected systems.
• Trojan horse: a type of malware that downloads onto a computer disguised as a legitimate program.
• spyware: a malicious software that enters a users computer, gathers data from the device and user, and sends it to third parties without their consent.
• phishing: a technique for attempting to acquire sensitive data througb fraudulent solicitation in email or on a website, in which the perpetrator masquerades as a legitimate business or reputable person.
• DDoS attack: a cybercrime in which the attacker floods a server with internet traffic to prevent users from accessing connected online services and sites.

• firewall: monitors and controls incoming and outgoing network traffic based on predetermined security rules.
• spam filter: algorithims that detect unsolicited, undesired, or infected emails and blocks those messages from reaching inboxes.
• proxy server: a system or router that provides a gateway between users and the internet.
• antivirus software: A program that monitors a computer or network to identify all major types of malware and prevent or contain malware incidents.
• cryptography: a proccess of hiding or coding information so that only the person a message was ntended for can read it.
• public key encryption: a method of encrypting or signing data with two different keys and making one of the keys, the public key, available for anyone to use. Tne other key is known as the private key.