100BASE-VG or 100VG-AnyLAN 100 Mbps communications that uses demand priority to transmit packets on a star topology network.
100BASE-X The 100 Mbps Fast Ethernet standard that uses the CSMA/CD access method for communications, as specified in the IEEE 802.3u standard.
access server A device that connects synchronous and asynchronous communication devices and telecommunication lines to a network, providing routing for those types of communications.
account lockout A security measure that prohibits logging on to an NT server account after a specified number of unsuccessful attempts.
active hub A network device that connects nodes in a star topology, regenerating, retiming, and amplifying the data signal each time it passes through the hub.
algorithm A block of computer code or logic designed to accomplish a certain task or to solve a problem, such as to control data communications or to calculate a payroll deduction.
American National Standards Institute (ANSI) An organization that works to set standards for all types of products, including network equipment.
American Standard Code for Information Interchange (ASCII) A commonly used character set consisting of 96 upper and lower case characters and numbers, plus 32 non-printing characters.
analog A type of transmission that can vary continuously, such as in a wave pattern with positive and negative voltage levels.
angular circumference Measurement of the amount of bend in a fiber-optic cable run.
AppleTalk A peer-to-peer protocol used on networks for communications between Macintosh computers.
asynchronous communications Communications that occur in discrete units where the start of a unit is signaled by a start bit at the front, and a stop bit at the back signals the end of the unit.
Asynchronous Transfer Mode (ATM) A transport method that uses multiple channels and switching to send voice, video, and data transmissions on the same network. ATM data transfer stresses efficient, QOS (quality of service), high-capacity data transport.
ATM switch A switching device that determines the network channel used to transmit an ATM cell received from a node, taking into account the type of information in the cell (i.e., voice, video, data) and the transmission speed needed.
attachment unit interface (AUI) A network interface that connects coax, twisted-pair, or fiber-optic backbone cable to a network node, such as a repeater, hub, or workstation. The interface consists of AUI standards for connectors, cable, interface circuits, and electrical characteristics.
attenuation The amount of signal that is lost as it travels through the communications medium from its source (transmitting node) to the receiving node. Attenuation in fiber-optic cable is measured as the drop in decibels.
auditing The ability to track past activities as a means to help identify and solve problems.
backbone A high-capacity communications medium that joins networks on the same floor in building, on different floors, and across long distances.
backbone cabling As defined by the EIA/TIA-568 standard, cable that runs between network equipment rooms, floors, and buildings.
backplane A main circuit board in modular equipment, containing slots as plug-ins for modular cards. The backplane provides connections between the modular boards, a power source, and grounding.
backup domain controller (BDC) An NT server that acts as a backup to the primary domain controller. It has a copy of the security accounts manager database containing user account and access privilege information.
baseband A type of transmission where the entire channel capacity of the communications medium (cable) is used by one data signal. Thus, only one node transmits at a time.
basic rate interface (BRI) An ISDN interface consisting of three channels. Two are 64 Kbps channels for data, voice, voice, and graphics transmissions. The third is a 16 Kbps channel used for communications signaling.
baud rate An older measurement of modem speed reflecting that one data bit is sent per each signal change (signal oscillation).
bayonet navy connector (BNC) A connector used for coax cable that has a bayonet-like shell. The female BNC connector has two small knobs that attach to circular slots in the male connector. Both connectors are twisted on for a connection. Other interpretations of the BNC name are bayonet nut connection and British Naval connector.
beaconing An error condition on a token ring network that indicates one or more nodes is not functioning.
benchmark Also called a baseline, a standard for hardware or software used to measure performance under varying loads or circumstances.
bits per second (bps) The number of binary bits (0s or 1s) sent in one second, a measure used to gauge network, modem, and telecommunications speeds.
bridge A network device that connects together different LAN segments using the same access method, such as one Ethernet LAN to another Ethernet LAN or a token ring LAN to another token ring LAN, utilizing layer 2 MAC addressing.
bridge protocol data unit (BPDU) A specialized packet used by bridges to exchange information with one another.
broadband ISDN (B-ISDN) An ISDN interface that is being developed to initially provide a data transfer rate of 155 Mbps. The theoretical limit is 622 Mbps.
broadband A transmission method using several transmission channels on a communications medium, allowing more than one node to transmit at the same time.
broadcast storm Saturation of network bandwidth by excessive broadcasts from devices attached to that network.
brouter Also called a multiprotocol router, acts like a bridge or a router, depending how it is set up to forward a given protocol.
bus topology A network configured so that nodes are connected to a segment of cable in the logical shape of a line, with a terminator at each end.
cable plant The total cabling that composes a network.
cable scanner A test device that measures the length of a network cable segment and tests for electrical opens (breaks) and shorts.
call-back security Used for remote communications verification, a security measure in which the remote server calls back the accessing workstation to verify that access is being requested from an authorized telephone number.
carrier sense The process of checking a communication media, such as cable, for a specific voltage level indicating the presence of a data-carrying signal.
Carrier Sense Multiple Access with Collision Detection (CSMA/CD) A network transport control mechanism used in Ethernet networks. It regulates transmission by sensing the presence of packet collisions.
cell A unit of data formatted for high-speed transmission over a network. Typically a cell contains a fixed amount of data and performs less error checking than a packet to achieve faster transmission.
cell relay A communications protocol that uses large fixed-length cells to transmit voice, video, and data.
channel service unit (CSU) A device that is a physical interface between a network device, such as a router, and a telecommunications line.
circuit switching A network communication technique that uses a dedicated channel to transmit information between two nodes.
Class A node An FDDI ring node, also called a dual-attached node, that is a network device, such as a hub that is connected to both rings in the FDDI architecture.
Class B node An FDDI node, also called a single-attached node, that is a workstation, server, or host computer that connects to the primary ring only and through that connects to a Class A node (hub).
client A computer which accesses a mainframe, minicomputer, or microcomputer that permits access to multiple users. The client may use the accessed computer (host) to process data, or may process accessed data using its CPU.
client/server application A software application where processing tasks are performed on the client or on one or more servers to achieve the best performance and to minimize network load.
cluster remapping A fault tolerance technique used by Windows NT to flag a damaged cluster and find an undamaged cluster on which to write data.
coaxial cable Also called coax, a cable with a copper core, surrounded by insulation. The insulation is surrounded by another conducting material, such as braided wire, which is covered by an outer insulating material.
collision A situation when two or more packets are detected at the same time on an Ethernet network.
Common Management Interface Protocol (CMIP) A protocol that is part of the OSI standards for network management to gather performance data on a network.
communications media The cabling or radio waves used to connect one network computer to another and transport data between them.
communications server A device that connects asynchronous serial devices to a network, providing only asynchronous routing.
community name A password used by network agents and the network management station so their communications cannot be easily intercepted by an unauthorized workstation or device.
Compressed Serial Line Internet Protocol (CSLIP) An extension of the SLIP remote communications protocol that provides faster throughput than SLIP.
computer virus Software that can spread throughout a computer, damaging files, file allocation tables, and other software components.
concentrator A device that can have multiple inputs and outputs all active at one time.
connectionless services Also known as Type 1 operation, services that occur between the LLC sublayer and the network layer, but provide no checks to make sure data accurately reaches the receiving node.
connection-oriented services Type 2 operation services that occur between the LLC sublayer and the network layer, providing several ways to ensure data is successfully received by the destination node.
Consultative Committee on International Telegraph and Telephone (CCITT) An international standards body that develops telecommunication standards for modems, digital telephone systems, and e-mail. For example, the CCITT X.400 standards are for international exchange of e-mail and the X.500 standards are for creating a worldwide e-mail directory. This is a branch of the International Telecommunications Union (ITU).
cyclic redundancy check (CDC) An error detection method that calculates a value for the total size of the information fields (header, data, and footer) contained in a frame. The value is inserted at the end of a frame by the data link layer on the sending node, and checked at the data link layer by the receiving node to determine if a transmission error has occurred.
data communications equipment (DCE) A network device that performs packet switching.
Data Encryption Standard (DES) A network encryption standard developed by the National Institute of Standards and Technology (NIST) and IBM.
Data Link Protocol (DLC) Available through Microsoft NT 4.0 and Windows 95, this protocol enables communications with an IBM mainframe or minicomputer.
data service unit (DSU) A device used with a CSU for communications over a telecommunications line. The DSU converts data to be sent over the line, and it converts data received from the line into a readable digital format.
data terminal equipment (DTE) Terminals, workstations, servers, and host computers that operate on a packet-switching network.
datagram A data transmission method that does not use a particular communication channel, causing data sent from one node to arrive at the destination node a different times, because each datagram may follow a different route to the destination. Datagrams do not use acknowledgment and are transmitted unattended.
defragmentation A software process that rearranges data to fill in the empty spaces that develop on disks and make data easier to obtain.
demand priority A data communications technique that transmits a packet directly from the sending node, through a hub, and to the receiving node, without making it available to other network nodes.
digital A transmission method that has distinct levels to represent binary 0s or 1s, such as On or Off or +5 volts and 0 volts.
discovery A process, used by routers, that involves gathering information about how many nodes are on a network and where they are located.
disk duplexing A fault tolerance method similar to disk mirroring in that it prevents data loss by duplicating data from a main disk to a backup disk; disk duplexing, however, places the backup disk on a controller or adapter different than is used by the main disk.
disk fragmentation A normal and gradual process in which files become spread throughout a disk and empty pockets of space develop between files.
disk mirroring A fault tolerance method that prevents data loss by duplicating data from a main disk to a backup disk. Some operating systems also refer to this as disk shadowing.
domain Network clients and resources used by the clients. User workstations and user groups compose the client side. File servers, print servers, and other network services are the resources.
domain name service (DNS) A TCP/IP application protocol that resolves domain computer names to IP addresses; or IP addresses to domain names.
driver Software that enables a computer to communicate with devices like NICs, printers, monitors, and hard disk drives. Each driver has a specific purpose, such as to handle Ethernet network communications.
dynamic addressing An addressing method in which an IP (Internet Protocol) address is assigned to a workstation without the need for the network administrator to hard-code it in the workstation’s network setup.
Dynamic Host Configuration Protocol (DHCP) A network protocol, DHCP that provides a way for a server to automatically assign an IP address to a workstation on its network.
dynamic routing A routing method where the router constantly checks the network configuration, automatically updates routing tables, and makes its own decisions (often based on guidelines pre-set by the network administrator) about how to route frames.
electromagnetic interference (EMI) Signal interference caused by magnetic force fields that are generated by electrical devices such as motors.
Electronic Industries Association (EIA) An organization that develops standards for electrical interfaces, such as serial interfaces on computers.
electronic mail (e-mail) Using mail software on a client to compose a message and send it to mail or post office software on one or more servers that forward the message to the intended destination. E-mail is possible due to networks and can span the globe thanks to the Internet.
encryption Turning data into an unintelligible sequence of characters. A key is used to translate the nonsense into the original information.
encryption key A digital password known to the sending node and the receiving node on a network.
enhanced mode When the computer processor is set to indirectly access computer memory, enabling it to run several programs at once.
enterprise network A network that reaches throughout a large area, such as a college campus, a city, or across several states, connecting many kinds of local area networks and network resources.
Ethernet A transport system that uses the CSMA/CD access method for data transmission on a network. Ethernet is typically implemented in a bus or star topology.
event management Used in network management software, a module where you can create filters and track designated network events, such as a device that is down, a partitioned segment, or network utilization over a specified percentage.
Event Viewer A tool with which to view events on an NT server or workstation that are recorded in the system, security, and application logs.
Extended Binary Coded Decimal Interchange Code (EBCDIC) A character coding technique used mainly on IBM mainframe computers, consisting of a specially coded 256-character set.
Fast Ethernet An Ethernet communications standard that operates at speeds up to 100 Mbps and is defined under the IEEE 802.3u standard (100BASE-X).
fat pipe Fiber-optic cable used on a network backbone for high-speed communications, such as between floors of a building.
fault tolerance Techniques that employ hardware and software to provide insurance against equipment failures, computer service interruptions, and data loss.
Fiber Distributed Data Interface (FDDI) A data transport method capable of a 100 Mbps transfer rate using a ring topology.
fiber-optic Communications cable consisting of one or more glass or plastic fiber cores inside a protective cladding material, and covered by a plastic PVC outer jacket. Signal transmission along the inside fibers is accomplished using infrared, or in some cases, visible light.
file server A network computer that makes software applications, data files, and network utilities available to other network nodes.
file transfer protocol (FTP) An application protocol within TCP/IP used to transfer data files from one computer system to another, such as from a workstation running a Microsoft operating system to a computer with the UNIX or IBM MVS operating system.
filter A capability in network monitoring software that enables the network manager to view only designated protocols, network events, network nodes, or other specialized views of the network.
firewall Hardware and software that protects portions of a network in two ways. One is by securing access to data and resources from outside intruders. The second is by preventing data from leaving the network through an inside source.
flow control A process that makes sure one device does not send information faster than can be received by another device.
frame Sometimes used interchangeably with the term packet, a unit of data formatted for transmission over a network.
frame relay A communications protocol that relies on packet-switching and virtual circuit technology to transmit data packets.
frequency division multiple access (FDMA) A form of multiplexing that creates separate channels on one communication medium by establishing different frequencies for each channel.
full backup A backup of an entire system, including all system files, programs, and data files.
gateway Hardware and software that enables communications between two different types of networked systems, such as between complex protocols or between different e-mail systems.
global group A type of Microsoft NT Server group used to make one Microsoft domain accessible to another, so that resources can be shared and managed across two or more domains.
group In Windows NT Server, a common entity that contains user accounts and network resources, such as file and print servers.
help desk Software that is used to keep data on hardware and software problems, how problems are solved, hardware and software setup information, and general computer documentation.
hertz The measurement of the frequency of the alternation of current or a radio wave.
home directory A dedicated location on a file server or a workstation for a designated account holder to store files.
hop The number of times a packet travels point-to-point from one network to the next. Another way to view a hop is the number of times the packet is regenerated, amplified, and placed onto another network by a source-route bridge (token ring) or router.
horizontal cabling As defined by the EIA/TIA-568 standard, cabling that connects to workstations and servers in the work area.
host A computer that has an operating system enabling multiple computers to access it at the same time. Programs and information may be processed at the host, or they may be downloaded to the accessing computer (client) for processing.
hot fix A data recovery method that automatically stores data when a damaged area of disk prevents that data from being written. The computer operating system finds another undamaged area on which to write the stored data.
hub A central network device used in the star topology to join single cable segments or individual LANs into one network.
Hypertext Markup Language (HTML) A formatting process that is used to enable documents and graphics images to be read on the World Wide Web. HTML also provides for fast links to other documents, to graphics, and to Web sites. The World Wide Web is a series of file servers with software such as Microsoft’s Internet Information Server (IIS), that make HTML and other Web documents available for workstations to access.
impedance The total amount of opposition to the flow of current. In coaxial cable, a 50-ohm impedance influences how fast a packet can travel in optimal conditions.
incremental backup A backup of new or changed files.
Institute of Electrical and Electronics Engineers (IEEE) An organization of scientists, engineers, technicians, and educators that has played a leading role in developing standards for network cabling and data transmissions.
Integrated Services Digital Network (ISDN) A standard for delivering data services over telephone lines, with a current practical limit of 64 Kbps and a theoretical limit of 622 Mbps.
intelligent hub A hub with network management and performance monitoring capabilities.
International Standards Organization (ISO) An international body that establishes communications and networking standards, and is best known for its contributions to network protocol standards.
Internet A world-wide network that is a collection of thousands of smaller networks tied together around the globe by a vast array of network equipment and communication methods.
Internet Control Message Protocol (ICMP) A protocol used to build information about the location of network workstations, servers, and other network equipment. It assists in determining the shortest path on which to send packets and it helps in locating network problems.
Internet Information Server (IIS) A Microsoft application that turns an NT server into a Web server for Internet and intranet communications.
Internet Packet Exchange (IPX) A protocol developed by Novell for use with its NetWare file server operating system.
intranet A private network within an organization. It uses the same Web-based software as the Internet but is highly restricted from public access. Intranets are currently used to enable managers to run high-level reports, to enable staff members to update human resources information, and to provide access to other forms of private data.
kilohertz Equal to 1000 hertz, a measurement of the frequency of the alternation of an electrical current or radio wave.
leased telephone line A line that is conditioned for high-quality transmissions and is a permanent connection without going through a telephone switch.
line of sight A type of signal transmission that is one where the signal goes from point to point, rather than one that bounces off the atmosphere to skip across the country or across continents. A limitation of line of sight is that transmissions are interrupted by large land masses, such as hills and mountains.
local area network (LAN) A series of interconnected computers, printers, and other computer equipment that share hardware and software resources. The service area is usually limited to a given floor, office area, or building.
local area transport (LAT) A protocol developed by DEC for virtual terminal communications.
local bridge A bridge that connects networks in close proximity and is used to segment a portion of a network to reduce heavy-traffic problems.
local group In Windows NT Server, a grouping of any combination of accounts, network resources, and global groups. It is used to manage accounts and resources within a single domain.
local router A router that joins networks within the same building or between buildings in close proximity, for example, on the same business campus.
locking An operating system process that prevents more than one user from updating a file or a record in a file at the same time.
logical link control (LLC) A sublayer housed in the data link layer of the OSI model and that initiates the communication link between two nodes as well as maintaining the link.
Management Information Base (MIB) A database of network performance information that is stored on a network agent for access by a network management station.
mapped drive A disk volume or folder that is shared on the network by a file server or workstation. It gives designated network workstations access to the files and data in its shared volume or folder. The workstation, via software, determines a drive letter for the shared volume, which is the workstation’s map to the data.
media access control (MAC) A sublayer of the OSI data link layer that examines addressing information contained in network packets.
megahertz Equal to 1 million hertz, a measurement of the frequency of the alternation of an electrical current or radio wave.
message switching A data transmission technique that sends data from point to point, with each intermediate node storing the data, waiting for a free transmission channel, and forwarding the data to the next point until the destination is reached.
metropolitan area network (MAN) A network that links multiple LANs within a large city or metropolitan region.
Microcom Network Protocol (MNP) A set of modem service classes that provide efficient communications, error correction, data compression, and high-throughput capabilities.
mission-critical A computer software application or a hardware service that has the highest priority in an organization.
modem A modulator/demodulator device that converts a transmitted digital signal to an analog signal for a telephone line and converts a received analog signal to a digital signal for use by a computer.
modular hub Also called a chassis hub, is one that contains a backplane into which different modules, such as such as retiming, bridge, routing, ATM modules can be inserted.
multiple master domain A domain model that consists of many domains in which domain management is located in two or more domains.
multimeter A device that measures a combination of electrical characteristics such as volts, ohms, and amperes.
multiplexer A switch that divides a communication medium into multiple channels so that several nodes can communicate at the same time. When a signal is multiplexed, it must be demultiplexed at the other end.
multiplexing A form of circuit switching where there are several physical channels connected to a switch called a multiplexer. Multiple computers also are connected to the switch, transmitting along the channels whose access is controlled by the switch.
multistation access unit (MAU) A central hub that links token ring nodes into a topology that physically resembles a star but where packets are transferred in a logical ring pattern.
Net Watcher A Microsoft monitoring tool used to view shared network resources and who is using them.
NetBIOS Extended User Interface (NetBEUI) A protocol that incorporates NetBIOS for communications across a network.
network A system of computers, communication devices, printers, and software linked together by communications cabling.
network agent A network device, such as a workstation or a router, that is equipped to gather network performance information to send to the network management station.
Network Basic Input/Output System (NetBIOS) A combination software interface and network-naming convention. It is available in Microsoft operation systems through the file, NetBIOS.dll.
network binding A process that identifies a computer’s network interface card or a dial-up connection with one or more network protocols to achieve optimum communications with network services. For Microsoft operating systems, you should always bind a protocol to each NIC that is installed.
Network Device Interface Specification (NDIS) A set of standards developed by Microsoft for network drivers that enables communication between a NIC and a protocol; and that enables the use of multiple protocols on the same network.
network file system (NFS) A UNIX-based network file transfer protocol that ships files as streams of records.
network interface card (NIC) An adapter card that enables a workstation, file server, printer, or other device to connect to a network and communicate with other network nodes.
network management station (NMS) A dedicated workstation that gathers and stores network performance data, obtaining that data from network nodes running agent software that enables them to collect the data. The NMS is loaded with network management software.
Network Monitor A Microsoft monitoring tool that captures and reports information about network performance.
Network Monitor Agent Microsoft software that enables a Microsoft workstation or server NIC to gather network performance data.
network traffic The number, size, and frequency of packets transmitted on the network in a given amount of time.
node Any device connected to a network, such as a microcomputer, mainframe, minicomputer, network equipment, or printer.
NWLink A network protocol that simulates the IPX/SPX protocol for Microsoft Windows 95 and NT communications with Novell NetWare file servers and compatible devices.
ohm meter A device that tests resistance and continuity in an electrical circuit.
one-way trust A domain trust relationship where one domain is trusted and one is trusting.
Open Datalink Interface (ODI) A driver that is used by Novell NetWare networks to transport multiple protocols on the same network.
Open Systems Interconnect (OSI) Developed by ISO and ANSI, a model that provides a framework for networked communications based on seven functional layers. It contains guidelines that can be applied to hardware and software network communications.
optical fault finder A device that measures power and distance characteristics in fiber-optic cable.
optical power meter A device that measures the light signal transmitted through fiber-optic cable.
packet A unit of data formatted for transmission over a network. A packet normally consists of a header containing information about its source and destination, the data to be transmitted, and a footer containing error-checking information.
packet assembler/disassembler (PAD) A device that converts data from a format used by a DCE (data communications equipment) to one that can be placed on an X.25 communications network; and it translates data received in an X.25 communications format to a format that can be read by a DCE.
packet switching A data transmission technique that establishes a logical channel between two transmitting nodes, but uses several different paths of transmission to continually find the best routes to the destination.
partition The process of shutting down an Ethernet segment because a portion of the segment is malfunctioning.
passive hub A network device that connects nodes in a star topology, performing no signal enhancement as the packet moves from one node to the next through the hub. Each time the signal moves through the hub it is weakened slightly because the hub absorbs some of it.
peer protocols Protocols used to enable an OSI layer on a sending node to communicate with the same layer on the receiving node.
peer-to-peer network A network where any computer can communicate with other networked computers on an equal or peer-like basis without going through an intermediary, such as a server or host.
Performance Monitor A Microsoft monitoring tool that captures and reports performance information about the computer that is running the monitor software and about the network to which that computer is connected.
permanent virtual circuit A data transmission method in which the communication channel stays connected at all times, even after the communication session is over.
permissions In Windows NT Server, privileges to control account or group access capabilities for reading, viewing, and changing files or folders.
Point-to-Point Protocol (PPP) A widely used remote communications protocol that supports IPX/SPX, NetBEUI, and TCP/IP for point-to-point communications (such as between a remote PC and an NT server on a network).
Point-to-Point Tunneling Protocol (PPTP) A remote communications protocol that enables connectivity to intranets (private virtual networks).
power budget For optical fiber cable communications, this is the difference between the transmitted power and the receiver sensitivity as measured in decibels. It is the minimum transmitter power and receiver sensitivity needed for a signal to be sent and received fully intact.
power supply A component in an electrical device that converts power from the wall outlet to the type and level of power required by the electrical device.
primary domain controller (PDC) An NT server that acts as the master server when there are two or more NT servers on a network. It holds the master database (called the SAM) of user accounts and access privileges.
primary rate interface (PRI) An ISDN interface that consists of switched communications in multiples of 1,536 Kbps.
primitive A command used to transfer information from one layer in an OSI stack to another layer, such as from the physical layer to the data link layer.
privileged mode A protected area from which the Windows NT operating system runs. Direct access to the computer’s memory or hardware is allowed only from this mode. Application programs that need to access memory and hardware issue a request to an operating system service rather than a direct memory or hardware instruction.
promiscuous mode Network devices that operate in this mode read frame destination address information before sending a packet onto other connected segments of the network.
protocol An established guideline specifying how networked data is formatted into a packet, how it is transmitted, and how it is interpreted at the receiving end.
protocol analyzer A device used to monitor one or more protocols transmitted across a network.
protocol data unit (PDU) The information transferred between layers in the same OSI stack.
public dial-up telephone line An ordinary telephone connection that is temporarily switched for the duration of the communication session.
radio frequency interference (RFI) Signal interference that is caused by electrical devices which emit radio waves at the same frequency as used by network signal transmissions.
real mode Setting a computer processor to run programs so they have direct access to memory locations at or below 1024K and so that only one program can be run at a time.
real-time application An application that involves immediate processing results, such as entering a new employee in a human resources database through an application that immediately updates the database as you are working.
redirector A Microsoft service used via the application layer to recognize and access other computers with operating systems such as Windows 3.11, Windows 95, Windows NT, LAN Manager, and LAN Server.
redundant array of inexpensive disks (RAID) A set of standards to extended the life of hard disk drives and to prevent data loss from a hard disk failure.
Registry A database used to store information about the configuration, program setup, devices, drivers, and other data important to the setup of a computer running Windows NT or 95.
Remote Access Services (RAS) Microsoft software services that enable off-site workstations to access an NT server through modems and analog telephone or ISDN telecommunication lines.
remote bridge A bridge that joins networks across the same city, between cities, and between states to create one network.
Remote Network Monitoring (RMON) A remote network monitoring standard that uses remote network nodes, such as workstations or network devices, to perform network monitoring, including gathering information for network protocol analysis.
remote router A router that joins networks across large geographic areas, such as between cities, states, and countries.
repeater A network device that amplifies and retimes a packet carrying signal so that it can be sent along all cable segments attached to the repeater.
request for information (RFI) A general planning document sent to vendors to obtain information about what services and products each vendor can offer.
request for proposal (RFP) A detailed planning document, often written from information received in RFIs, that is sent to vendors containing exact specifications for services and products that an organization intends to purchase.
resolution A process used to translate a computer’s domain name to an IP address and vice versa.
resource On a workstation, an IRQ, I/O address, or memory that is allocated to a computer component, such as a disk drive or communications port. On an NT server network, a resource is a file server, shared printer, or shared directory that can be accessed by users.
rights In Windows NT Server, high-level access privileges for activities such as to log on to a server, to shut down a server, and to create user accounts.
ring topology A network in the form of a continuous ring or circle, with nodes connected around the ring.
RMON management station A dedicated workstation that gathers and reports on RMON data collected by probes.
RMON probes Remotely located workstations, servers, and network devices equipped with RMON software used to monitor a network and send information to a RMON management station for analysis.
router A device that connects networks having the same or different access methods, such as Ethernet to token ring. It forwards packets to networks by using a decision making process based on routing table data, discovery of the most efficient routes, and pre-programmed information from the network manager.
sector sparing Available in Windows NT Server and NT Workstation for SCSI drives, a fault tolerance method that reserves certain hard disk sectors so they can be used when a bad sector is discovered.
security accounts manager (SAM) database Also called the directory services database, stores information about user accounts, groups, and access privileges on a Microsoft Windows NT server.
segment of cable A cable run within the IEEE specifications, such as one run of 10BASE2 cable that is 185 meters long and that has 30 nodes or less (including terminators and network equipment).
segmenting A technique to isolate and direct network traffic to reduce bottlenecks and to reduce the impact of a network malfunction on other portions of the network.
Sequence Packet Exchange (SPX) A Novell connection-oriented protocol used for network transport where there is a particular need for data reliability.
serial communications Data transmissions that use one channel to send data bits one at time. Terminals and modems use serial communications. The serial communications port on a PC conforms to the EIA/TIA-232 (formerly RS-232) standard for communications up to 64 Kbps.
Serial Line Internet Protocol (SLIP) An older remote communications protocol used by UNIX computers.
service data unit (SDU) The protocol data unit (PDU) with the control and transfer information stripped out.
shielded twisted-pair (STP) Cable that contains pairs of insulated wires that are twisted together, surrounded by a shielding material for added EMI and RFI protection, all inside a protective jacket.
Simple Mail Transfer Protocol (SMTP) An e-mail protocol used by systems having TCP/IP network communications.
Simple Network Management Protocol (SNMP) A protocol that enables computers and network equipment to gather standardized data about network performance and is part of the TCP/IP suite of protocols.
single master domain A relationship model in a domain or domains in which trusts are set up so that management control is centralized in only one domain.
small computer system interface (SCSI) A 32- or 64-bit computer adapter that transports data between the computer and one or more attached devices, such as hard disks. There are several types of SCSI adapters, including SCSI, SCSI-2, SCSI-3, SCSI wide, SCSI narrow, and UltraSCSI. All are used to provide high-speed data transfer to reduce bottlenecks within the computer.
SNMP Monitor A Microsoft network-monitoring tool that can query MIB (Management Information Base) information on network agents and store that information to put in ODBC compatible databases.
spanning tree algorithm Ensures packets are not transmitted in an endless loop and it enables packets to be sent along the most cost-effective network path as determined by: (a) the shortest path from source to the destination and (b) the most effective use of cable resources for the type of information sent.
spindle A rod attached to the center of a hard disk platter and to a motor used to rotate the rod and disk.
spread spectrum technology (SST) Communications technology used by wireless networks in place of cable for communications between network nodes. Network data are transmitted by means of reliable high-frequency radio signals.
standalone server An NT server that is used as a special purpose server, such as to store databases. It does no account logon verification.
star topology A network configured with a central hub and individual cable segments connected to the hub, resembling the shape of a star.
static addressing An IP addressing method that requires the network administrator to assign and set up manually a unique network address on each workstation connected to a network.
static routing A routing method that involves control of routing decisions by the network manager through pre-set routing instructions.
statistical multiple access A multiplexing technique that allocates the communication resources according to what is needed for the task, such as providing more bandwidth for a video file and less for a small spreadsheet file.
striping A data storage method that breaks up data files across all volumes of a disk set to minimize wear on a single volume.
subnet mask A method to show which part of the IP address is a unique identifier for the network and which part uniquely identifies the workstation. On a simple network, the subnet mask would be 255.255.0.0, which would indicate that the first two sets of digits (denoted by 255) are the network identification for that network and the third and fourth sets of digits (denoted by the zeroes) are used as the workstation identification.
switched megabit data service (SMDS) Also called switched multimegabit data service, a data transport method developed by regional telephone companies to provide cell-based, high-speed communications between metropolitan area networks.
switched virtual circuit A communication channel that is established for only as long as the communication session lasts.
synchronous communications Continuous bursts of data controlled by a clock signal that starts each burst (like a starter at a cross country foot race who fires a starting pistol at certain intervals to start different heats of runners on the same course). Each bit that is sent is synchronized at specific intervals.
Systems Management Server (SMS) A network management and client troubleshooting system developed by Microsoft.
Systems Network Architecture (SNA) A layered communications protocol used by IBM for communications between IBM mainframe computers and terminals.
synchronous optical network (SONET) A fiber-optic technology that allows for high-speed (over 1 Gbps) data transmission. Networks based on SONET can deliver voice, data, and video.
T-carrier A dedicated telephone line for data communications.
Telecommunications Industry Association (TIA) A group formed as a body within the Electronic Industries Association to develop telecommunications and cabling standards.
Telnet A TCP/IP application protocol that provides terminal emulation services.
terahertz Equal to 1 trillion hertz, a measurement of the frequency of the alternation of an electrical current or radio wave.
terminal A device that consists of a monitor and keyboard to communicate with a host computer that runs the programs. The terminal does not have a processor to use for running programs locally.
terminal adapter (TA) Popularly called a digital modem, a device that links a computer or a fax to an ISDN line.
time division multiple access (TDMA) A multiplexing method that enables multiple devices to communicate over the same communications medium by creating time slots in which each device transmits.
time domain reflectometer (TDR) A device that measures network cable characteristics such as distance, impedance, levels of RFI/EMI, and the presence of opens and shorts.
token ring Using a ring topology, a network transport method that passes a token from node to node. The token is used to coordinate transmission of data, because only the node possessing the token can send data.
topology The physical layout of the cable and the logical path followed by network packets sent on the cable.
transaction tracking Also called transaction logging or journaling, a fault tolerance method in which a log is kept of all recent transactions until they are written to disk. If a hard disk or system failure occurs, unwritten transactions are recovered from the log.
Transmission Control Protocol/Internet Protocol (TCP/IP) A protocol particularly well suited for medium and large networks. The TCP portion was originally developed to ensure reliable connections on government, military, and educational networks. It performs extensive error checking to ensure data is delivered successfully. The IP portion consists of rules for packaging data and ensuring it reaches the correct destination address.
trusted domain A domain that has been granted security access to resources in another domain.
trusting domain A domain that allows another domain security access to its resources, such as file servers.
trust relationships These establish how resources are accessed in Microsoft domains, providing a way to manage both resources and user accounts.
twisted-pair Flexible communications cable that contains pairs of insulated copper wires which are twisted together for reduction of EMI and RFI and covered with an outer insulating jacket.
two-way trust A domain relationship in which both domains are trusted and trusting.
uninterruptible power supply (UPS) A device built into electrical equipment or a separate device that provides immediate battery power to equipment during a power failure or brownout.
universal trust A domain relationship among three or more domains in which every domain is trusting and trusted with every other domain.
unshielded twisted-pair (UTP) Communications cable that has no shielding material between the pairs of insulated wires twisted together and the cable’s outside jacket.
virtual circuit A logical communication path established by the OSI network layer for sending and receiving data.
virtual LAN (VLAN) Using ATM switches, routers, and internetworking software, a network manager can configure a network into subnetworks of logical workgroups, independent of the physical network topology.
virtual memory Disk space allocated to link with memory to temporarily hold data when there is not enough free RAM.
voltmeter A device that tests the voltage in an electrical circuit.
Web browser A tool that enables the user to view or search for information and display text, graphics, sound and video from the World Wide Web. Web browsers also can be used to search for information through a private network. Microsoft Internet Explorer and Netscape Communicator are two examples of popular Web browsers.
wide area network (WAN) A far reaching system of networks that can extend across state lines and across continents.
Windows Internet Naming Service (WINS) A Windows NT Server service that enables the server to convert workstation names to IP addresses for Internet communications.
wiring closet A centrally located enclosed room dedicated to house network, telephone, and video cable and associated equipment.
wizard A set of automated dialog boxes and screens that take you, step-by-step, through a particular setup or administrative function on a computer running Microsoft software
workgroup As used in Microsoft networks, a number of users who share drive and printer resources in an independent peer-to-peer relationship.
workstation A computer that has its own CPU and may be used as a stand-alone computer for word processing, spreadsheet creation, or other software applications. It also may be used to access another computer such as a mainframe computer or file server, as long as the necessary network hardware and software are installed.
World Wide Web A vast network of servers throughout the world that provide access to voice, text, video, and data files.
X.25 A packet-switching protocol for connecting remote networks at speeds up to 64 Kbps.
Xerox Network System (XNS) A protocol developed by Xerox in the early networking days for Ethernet communications.