IT Lexicon
- 2. 1.NETWORK: A network is any collection of independent computers that communicate with one another over a shared network medium. 2.INTERNET: The Internet is a system of linked networks that are worldwide in scope and facilitate data communication services such as remote login, file transfer, electronic mail, the World Wide Web and news groups. 3.DATACOMMUNICATION: Data communication is the exchange of data between two devices via some from of transmission medium. (such as a wire cable). 4.MESSAGE: The message is the information(data) to be communicated. It can consist of text, numbers, pictures, sound, etc. 6.MEDIUM: The transmission medium is the physical path by which a message travels from sender to receiver.
- 3. 7.PROTOCOL: A protocol is a set of rules that govern data communication. It represents an agreement between the communicating devices. 8.LINK: A link is the physical communication pathway that transfers data from one device to another. 9.TOPOLOGY: The term topology refers to the way a network is laid out, either physically or logically. 10.MESH: In a mesh topology , every device has a dedicated point-to- point link to every other device. 11.STAR: In a star topology, each device has a dedicated point-to-point link only to a central controller, usually called a hub. 12.BUS: A bus topology, on the other hand, is multipoint. One long cable acts as a backbone to link all the devices in the network.
- 4. 13.RING: In a ring topology, each device has a dedicated point-to- point line configuration only with the two devices on either side of it. 14.INTERNETWORKS: When two or more networks are connected, they become an internetwork. 15.SIMPLEX: Simplex transmission means the data flows in one direction only. 16.HALF-DUPLEX: This transmission means allows data to flow in both direction, but not at the same time. 17.FULL-DUPLEX: This transmission allows data to flow in both direction at the same time.
- 5. LAN: A LAN is a data communication system within a building, plant, or campus, or between nearby buildings. MAN: A MAN is a data communication system covering an area the size of a town or city. WAN: A WAN is a data communication system spanning states, countries, or the whole world. CLIENT: A client is a finite program running on the local machine requesting service from a server. SERVER: A server is a infinite program running on the remote machine providing service to the clients.
- 6. DNS: Domain Name System is a client-server application that identifies each host on the internet with a unique user-friendly name. TELNET: Telnet is a client-server application that allows a user to log on the remote machine, giving the user access to the remote system. FTP: File Transfer Protocol is a TCP/IP client-server application for copying files from on host to another. SMTP: The TCP/IP protocol that supports e-mails on the internet is called Simple Mail Transfer Protocol. MIME: Multipurpose Internet Mail Extension is an extension of SMTP the allows the transfer of multimedia messages.
- 7. HTTP: Hypertext Transfer Protocol is the main protocol used to access data on the World Wide Web(WWW). NOISE: Noise is the external energy that corrupts a signal. MULTIPLEXING: Multiplexing is the set of techniques that allows the simultaneous transmission of multiple signals across a single data link. PATH: The word path refers to the physical link. CHANNEL: The word channel refers to a portion of a path that carries a transmission between a given pair of devices. One path can have many(n) channels.
- 8. SINGLE-BIT ERROR: The term single-bit error means that only bit of a given data unit is changed form 1 to 0 or from 0 to 1. BURST ERROR: The term Burst error means that two or more bits in the data unit have changed from 1 to 0 or form 0 to 1. CHECKSUM: Checksum is used by the higher-layer protocols(TCP/IP) for error detection. ERROR CONTROL: Error control means error detection and correction. SLIDING WINDOW: Sliding window method of flow control, several frames can be in transit at a time.
- 9. PROTOCOL: Protocol refers to a set of rules for executing a particular task. DATA LINK PROTOCOL: A data link protocol is a set of specifications used to implement the data link layer. BACKBONE: The major transmission path in a network. BASEBAND: Referring to a technology in which a signal is transmitted directly onto a channel without modulating a carrier. BROADBAND: Referring to a technology in which a signal shares the bandwidth of a medium.
- 10. BANDWIDTH: It measures the information –carrying capacity of a line or a network. BAUD RATE: The number of signal elements transmitted per second. A signal element consists of one or more bits. IP: The IP packet, called the datagram, consists of a variable header and a variable data field. INTERNET ADDRESS: An internet address(better known as the IP address) uniquely defines the connection of host to its network. ARP: The Address Resolution Protocol(ARP) finds the physical address of a device if its IP address is known.
- 11. RARP: The Reverse Address Resolution Protocol(RARP) will find a host’s IP address from its physical address. ICMP: The Internet Control Message Protocol(ICMP) handles control and error messages in the IP layer. UDP: UDP is unreliable and connectionless. UDP communication is port-to-port. The UDP packet is called a user datagram. TCP: TCP is reliable and connection-oriented. TCP communication is also port-to-port. The packet is called a segment. PROTCOL PORT: is a source or destination point of an executing program in the application layer.
- 12. HUB: A central device in a star topology that provides a common connection among the nodes. HOSTID: The part of an IP address that identifies a host. GATEWAY: A device used to connect two separate networks that use different communication protocols. FLOW CONTROL: A technique to control the rate of flow of frames(packets or messages). FRAME: A group of bits representing a block of data. FLOODING: Saturation of a network with a message.
- 13. DOMAIN NAME SYSTEM (DNS): A TCP/IP application service that converts user-friendly names to IP address. DATA LINK LAYER: The second layer of the OSI model. It is responsible for node-to-node delivery. DATA TRANSFER: The movement of data from one location to another. ENCODING: Transforming information into signal. ENCRYPTION: Converting a message into an unintelligible form that is unreadable unless decrypted.
- 14. DECODONG: Process of restoring an encoded message to its pre- encoded form. DECRYPTION: Recovery of the original message from the encrypted data. DIALOG: The exchange between two communicating devices. DISTORTION: Any change in a signal due to noise, attenuation, or other influences. DOWNLINK: transmission from a satellite to an earth station. DOWNLOADING: Retrieving a file or data from a remote site.
- 15. ERROR: Mistake in data transmission. FREQUENCY: The number of cycles per second of a periodic signal. HANDSHAKING: A process to establish or terminate a connection. LINE CONFIGURATION: The relationship between communication devices and their pathway. LINK: The physical communication pathway that transfers data from one device to another. LOGICALADDRESS: The address defined in the network layer.
- 16. LOSS CONTROL: A transport layer function that ensures that all data units of a transmission arrive at the destination. LOSSLESS DATA COMPRESSION: Data compression in which no data are lost. LOSSY DATA COMPRESSION: Data compression in which some original data are lost. MICROWAVE: Electromagnetic waves ranging form 2 GHz to 40 GHz. NODE: An addressable communication device(e.g., a computer or router) in a network.