Network +

A type of cable containing twisted-wire pairs that are not only individually insulated, but also surrounded by a shielding made of a metallic substance such as foil.

A form of cable that contains one or several glass or plastic fibers in its core. Data is transmitted via pulsing light sent from a laser or light-emitting diode (LED) through the central fiber (or fibers). Fiber-optic cables offer significantly higher throughput than copper-based cables. They may be single-mode or multimode and typically use wave division multiplexing to carry multiple signals.

A type of interference that may be caused by motors, power lines, televisions, copiers, fluorescent lights, or other sources of electrical activity.

A type of transmission in which signals may travel in both directions over a medium simultaneously. May also be called, simply, "duplex."

An IEEE Physical layer standard for achieving 10-Mbps throughput over coaxial copper cable. Thinnet is also known as 10Base-2. Its maximum segment length is 185 meters, and it relies on a bus topology.

An IEEE Physical layer standard for achieving a maximum of 10-Mbps throughput over coaxial copper cable. Thicknet is also known as 10Base-5. Its maximum segment length is 500 meters, and it relies on a bus topology.

The delay between the transmission of a signal and its receipt.

The unwanted signals, or interference, from sources near network cabling, such as electrical motors, power lines, and radar.

A type of cable that consists of a central metal conducting core, which might be solid or stranded and is often made of copper, surrounded by an insulator, a braided metal shielding, called braiding, and an outer cover, called the sheath or jacket. Coaxial cable, called "coax" for short, was the foundation for Ethernet networks in the 1980s. Today it's used to connect cable Internet and cable TV systems.

The amount of data that a medium can transmit during a given period of time. Throughput is usually measured in megabits (1,000,000 bits) per second, or Mbps. The physical nature of every transmission media determines its potential throughput.

A relatively short section (usually between 3 and 25 feet) of cabling with connectors on both ends.

A twisted pair patch cable in which the termination locations of the transmit and receive wires on one end of the cable are reversed.

A type of cable similar to telephone wiring that consists of color-coded pairs of insulated copper wires, each with a diameter of 0.4 to 0.8 mm, twisted around each other and encased in plastic coating.

As opposed to analog signals, digital signals are composed of pulses that can have a value of only 1 or 0.

A measure of the difference between the highest and lowest frequencies that a medium can transmit.

A type of cable in which the terminations on one end are exactly the reverse of the terminations on the other end. It is used for serial connections between routers and consoles or other interfaces.

The extent to which a signal has weakened after traveling a given distance.

A type of transmission in which signals may travel in both directions over a medium, but in only one direction at a time.

A twisted pair patch cable in which the wire terminations in both connectors follow the same scheme.

A form of transmission in which signals are modulated as radiofrequency analog pulses with different frequency ranges. Unlike baseband, broadband technology does not involve binary encoding. The use of multiple frequencies enables a broadband system to operate over several channels and, therefore, carry much more data than a baseband system.

A form of transmission in which digital signals are sent through direct current pulses applied to a wire. This direct current requires exclusive use of the wire's capacity, so baseband systems can transmit only one signal, or one channel, at a time. Every device on a baseband system shares a single channel.

A type of cabling that consists of one or more insulated wire pairs encased in a plastic sheath. - As its name implies, UTP does not contain additional shielding for the twisted pairs. As a result, UTP is both less expensive and less resistant to noise than STP.

A computer that runs a desktop operating system and connects to a network.

The devices, data, and data storage space provided by a computer, whether stand-alone or shared.

A computer that manages Web site services, such as supplying a Web page to multiple users on demand.

A computer on the network that requests resources or services from another computer on a network. In some cases, a client could also act as a server. The term client may also refer to the user of a client workstation or a client software application installed on the workstation.

A network of computers and other devices that is confined to a relatively small space, such as one building or even one office.

The software that runs on a server and enables the server to manage data, users, groups, security, applications, and other networking functions. The most popular network operating systems are Microsoft Windows NT, Windows 2000 Server, and Windows Server 2003, UNIX, Linux, and Novell NetWare.

A computer that enables resource sharing by other computers on the same network.

A network that spans a long distance and connects two or more LANs.

A person working on a computer on a different network or in a different geographical location from the LAN's server.

The means through which data are transmitted and received. Transmission media may be physical, such as wire or cable, or atmospheric (wireless), such as radio waves.

A computer on the network that manages shared resources. Servers usually have more processing power, memory, and hard disk space than clients. They run network operating software that can manage not only data, but also users, groups, security, and applications on the network.

The skills such as customer relations, leadership ability, and dependability, which are not easily measured, but are nevertheless important in a networking career.

A group of computers and other devices (such as printers) that are connected by and can exchange data via some type of transmission media, such as a cable, a wire, or the atmosphere.

A standard method or format for communication between network devices. Protocols ensure that data are transferred whole, in sequence, and without error from one node on the network to another.

A network in which every computer can communicate directly with every other computer. By default, no computer on a peer-to-peer network has more authority than another. However, each computer can be configured to share only some of its resources and keep other resources inaccessible to other nodes on the network.

The device that enables a workstation to connect to the network and communicate with other computers. NICs are manufactured by several different companies and come with a variety of specifications that are tailored to the workstation's and the network's requirements. NICs are also called network adapters.

A network that uses centrally administered computers, known as servers, to enable resource sharing for and to facilitate communication between the other computers on the network.

The seventh layer of the OSI model. Application layer protocols enable software programs to negotiate formatting, procedural, security, synchronization, and other requirements with the network.

The lower sublayer of the Data Link layer. The MAC appends the physical address of the destination computer onto the frame.

The fourth layer of the OSI model. In the Transport layer protocols ensure that data are transferred from point A to point B reliably and without errors. Transport layer services include flow control, acknowledgment, error correction, segmentation, reassembly, and sequencing.

A core protocol in the TCP/IP suite that operates in the Network layer of the OSI model and provides information about how and where data should be delivered. IP is the subprotocol that enables TCP/IP to internetwork.

The upper sublayer in the Data Link layer. The LLC provides a common interface and supplies reliability and flow control services.

A core protocol in the TCP/IP suite that operates in the Network layer of the OSI model and provides information about how and where data should be delivered. IP is the subprotocol that enables TCP/IP to internetwork.

The third layer in the OSI model. Protocols in the Network layer translate network addresses into their physical counter Internet Protocol See IP.

The lowest, or first, layer of the OSI model. Protocols in the Physical layer generate and detect signals so as to transmit and receive data over a network medium. These protocols also set the data transmission rate and monitor data error rates, but do not provide error correction.

The process of wrapping one layer's PDU with protocol information so that it can be interpreted by a lower layer. For example, Data Link layer protocols encapsulate Network layer packets in frames.

A type of Transport layer protocol that requires the establishment of a connection between communicating nodes before it will transmit data.

A response generated at the Transport layer of the OSI model that confirms to a sender that its frame was received. The ACK packet is the third of three in the three-step process of establishing a connection.

A networking technology developed by IBM in the 1980s. It relies upon direct links between nodes and a ring topology, using tokens to allow nodes to transmit data.

A unique identifying number for a network node that follows a hierarchical addressing scheme and can be assigned through operating system software. Network addresses are added to data packets and interpreted by protocols at the Network layer of the OSI model.

The fifth layer in the OSI model. The Session layer establishes and maintains communication between two nodes on the network. It can be considered the "traffic cop" for network communications.

A 12-character string that uniquely identifies a network node. The manufacturer hard codes the MAC address into the NIC. This address is composed of the block ID and device ID.

A method of gauging the appropriate rate of data transmission based on how fast the recipient can accept data.

The second layer in the OSI model. The Data Link layer bridges the networking media with the Network layer. Its primary function is to divide the data it receives from the Network layer into frames that can then be transmitted by the Physical layer.

The sixth layer of the OSI model. Protocols in the Presentation layer translate between the application and the network. Here, data are formatted in a schema that the network can understand, with the format varying according to the type of network used. The Presentation layer also manages data encryption and decryption, such as the scrambling of system passwords.

A networking technology originally developed at Xerox in the 1970s and improved by Digital Equipment Corporation, Intel, and Xerox. Ethernet, which is the most common form of network transmission technology, follows the IEEE 802.3 standard.

A type of Transport layer protocol that services a request without requiring a verified session and without guaranteeing delivery of data.

The upper sublayer in the Data Link layer. The LLC provides a common interface and supplies reliability and flow control services.

A package for data that includes not only the raw data, or "payload," but also the sender's and recipient's addressing and control information. Frames are generated at the Data Link layer of the OSI model and are issued to the network at the Physical layer.

The Network layer address assigned to nodes to uniquely identify them on a TCP/IP network. IP addresses consist of 32 bits divided into four octets, or bytes.