10Base2 An Ethernet topology using thin Ethernet coaxial cable, also known as
Thin Ethernet or thinnet. The maximum distance per segment is 185 meters. 10Base5 An Ethernet topology using thick Ethernet coaxial cable, also known as Thick Ethernet or thicknet. 10Base5 was once commonly used for backbones in
Ethernet networks. This is an older network architecture that has been replaced by 10BaseT, 100BaseT, and now 1000BaseT. The maximum distance per segment is 500 meters.
10BaseT An Ethernet topology using unshielded twisted-pair cable, also known as twisted pair. 10BaseT has become the most popular Ethernet cable, because many buildings are already wired for 10BaseT. It is inexpensive and easy to work with, and if the cable specifi cations are CAT 5, it can transmit data at 100 Mbps. The maximum distance per segment is 100 meters.
100BaseT An Ethernet topology using CAT 5 twisted-pair cable to transmit at 100 Mbps, also known as Fast Ethernet. The maximum distance per segment is 100 meters.
1000BaseT An Ethernet topology using CAT 5e twisted-pair cable to transmit at 1000 Mbps, also known as Gigabit Ethernet. The maximum distance per segment is 100 meters.
Access Control Entries (ACE) An entry within the access control list that specifi es an auditing entry or an access permission for a security principle such as specifi c user, or for a group of users on an object.
Access Control List (ACL) A list of security permissions or audit settings to an object.
Access Methods The rules governing the use of the physical network by various devices. An access method determines how data is submitted on the wire.
Two examples of access methods are token passing and CSMA /CD.
Access Permissions Access permissions are types of access to an object within an operation system. Windows includes a number of access permissions including read, execute, and modify.
Account An account, or user account, provides access to the network. It contains the information enabling a person to use the network, including user name and logon specifi cations, password, and rights to directories and resources.
Account Lockout A feature that locks out an account after a certain number of unsuccessful logon attempts (three bad attempts are a common choice). Typically, a locked account can no longer be used until the administrator unlocks it. This helps to prevent hackers from breaking into accounts.
Account Policies A set of rules for password usage and account lockout.
Account Restrictions Determine when and how a user gains access to the network.
ACE See Access Control Entries.
Acknowledgment (ACK) A packet of information sent from the recipient computer to the sending computer, for the purpose of verifying that a transmission has been received. An unsuccessful transmission will generate a negative acknowledgment (NACK).
ACL See Access Control List.
Active Directory Microsoft Windows 2000/2003 directory service holding network accounts, groups, and group policy objects.
Active Hub A hub device used in a star topology to regenerate the signal and distribute data to each node connected to the hub. Unlike a passive hub, the active hub requires electricity. See also Hub, and Passive Hub.
Active Partition Indicates which bootable partition is booted from when the system is powered on.
Adapter The term used for a card that is inserted into the system to provide functionality such as a network adapter, which provides connectivity to the network.
Address Resolution The process of fi nding the address of a host using another address form. For example, when the IP address is used it must be resolved to the
MAC address.
Address Resolution Protocol (ARP) Used to determine a host.s MAC address from its IP address. To accomplish this feat, ARP sends out a broadcast message (an ARP request packet that contains the IP address of the system it is trying to fi nd). All systems on the local network detect the broadcast message, and the system that owns the IP address for which ARP is looking replies by sending its physical address to the originating system in an ARP reply packet. The physical /IP address combo is then stored in the ARP cache of the originating system for future use. See also Media Access Control.
Administrator Account The account used to administer the settings on a
Windows Server and network. This account is created during install and has unlimited access to the server. Care must be taken when logged on to a server as an administrator, because administrator access rights include the capability to shut down the server and erase critical data.
Advanced Research Project Agency Network (ARPANET) Funded as a research project by the U.S. Department of Defense, ARPANET was created to enable networks to communicate with each other and to provide redundancy in case of war. As the fi rst internetwork, ARPANET was the precursor to the Internet.
American Standard Code for Information Interchange (ASCII) A representation of standard alphabetic and other keyboard characters in a computer-readable, binary format.
Analog A data transmission whose frequency varies and is usually associated with telephone communications.
Analog Modem Analog modems are used to connect to a remote network via a standard telephone (PSTN) line. Although there are many different types and makes of modems, they can be categorized into three areas: single external, single internal, and multiline rack mounted.
AppleTalk AppleTalk is the proprietary protocol developed by Apple Computer, and is rarely found in network environments where Apple computers are not present. AppleTalk is a routable protocol.
Application Layer OSI layer that provides a consistent way for an application to make a network request. Examples of application-layer protocols are HTTP, SMTP, and FTP.
Application Server A server that runs a networking application such as email or a database server. Application servers typically have a client that makes a connection to the application server from the user.s desktop.
Archiving A process that enables you to move old fi les off the fi le server to free up disk space for new fi les. If the old fi les are later needed, they can be unarchived and retrieved. Archived data can be saved to CD, DVD, WORM, or tape.
ArcNet See Attached Resource Computer Network.
ARP See Address Resolution Protocol.
ARPANET See Advanced Research Project Agency Network.
Array Controller The best way to incorporate disk mirroring is at the hardware level with what is known as an array controller. An array controller is an interface card that connects to both drives in a RAID solution.
ASCII See American Standard Code for Information Interchange.
Asynchronous Communication Communication that does not require both the sender and receiver to be online and participating in the communication at the same time.
Asynchronous Transfer Mode (ATM) A packet-switching network technology for LANs and WANs that can handle voice, video, and data transmissions simultaneously.
Attached Resource Computer Network (ArcNet) A bus network topology that is similar to Token Ring in that it uses a token to transmit data across the network. ArcNet transmits data at 2.5 Mbps and can run on coaxial, twisted-pair, and fi ber-optic cable. This networking standard used to be common but has lost popularity because of its limited transmission speeds.
Attachment Unit Interface (AUI) Enables a network card to be used with multiple types of media. The AUI connector is a female 15-pin D connector that looks very much like a joystick port. Also called a DIX (Digital-Intel-Xerox) connector.
Attributes A characteristic of a fi le. A fi le can be designated with different fi le system attributes or fi le system characteristics such as Read Only, System, Hidden, and Archive.
AUI See Attachment Unit Interface.
Back Door A method a hacker uses to gain access to a system. This back door may be available due to a vulnerability in the system or as a result of a previous attack.
Backbone The main cable that interconnects networks.
Backup The process of saving fi les to a separate location, usually an offl ine storage location or medium, such as tape.
Backup Domain Controller (BDC) A computer that contains a backup of a domain.s security policy and accounts database in a Windows NT 4.0 network. This database is maintained by the Primary Domain Controller. A BDC is not required but is recommended.
Backup Set A backup set is a group of fi les, directories, or disks selected for a single backup operation.
Bad Sector A damaged or nonworking area of a hard disk. If data has been saved to that area, it cannot be accessed.
Bandwidth The amount of data that the media can transfer. Bandwidth is usually measured in bits per second (bps).
Base I/O Address The memory address that identifi es where data will fl ow to and from the hardware device on the computer.
Baseband Transmission Technique used to transmit encoded signals over cable using digital signaling at the same frequency. See also Broadband Transmission.
Baseline A snapshot of your system or network under normal operating conditions that is used as a yardstick to measure future abnormalities.
BC See Bearer Code.
BDC See Backup Domain Controller.
Bearer Code (BC) An identifi er made up of the combination of TEI and SAPI.
It is used as the call reference and is dynamic, like the two identifi ers included within it.
Binary Representation Any value represented with just zeros and ones.
Binding The linking of network components on different levels to enable communication between those components. For example, binding a protocol to a network adapter allows the network adapter to communicate with that protocol.
Bit Order The order in which computers transmit binary numbers across a network. Computers can start at either end of a binary number when transmitting it across a network.
Blue Screen of Death (BSD) Text-mode stop messages that identify hardware and software problems that have occurred while running Windows operating systems.
BNC See British Naval Connector.
BOOT.INI File A fi le on Windows systems used to control the booting of the operating system and construct the Operating System selection menu.
Boot Partition The boot partition in Windows is the partition containing the operating system fi les.
Boot PROM (Programmable Read Only Memory) Boots the workstation if there is not a hard drive or disk to boot from.
Boot Protocol (BOOTP) The Boot Protocol, known as BOOTP, is used by diskless workstations. When a diskless workstation boots, it does so using an
EEPROM on the network card to allow it to load basic drivers and connect to the network. A BOOTP server, similar to a DHCP server, assigns the diskless workstation an address for the network to allow it to participate on the network.
Bootup The process a computer executes when powered up. Bootup includes the fi les that initialize the hardware and the starting of the operating system.
Bottleneck Indicates that a component within your system has limitations that impede the system as a whole from operating at its maximum potential.
Bridge An OSI layer-2 hardware device that connects two LAN segments of either the same or different topologies. Bridges look at the destination and source
MAC addresses of a network packet and decide whether to pass that packet on to the LAN segment. A bridge can be used to fi lter out traffi c for a local subnet and prevent it from being passed on to an unnecessary LAN segment.
British Naval Connector (BNC) Also known as a barrel connector, the connector type used in 10Base2 (Thin Ethernet) networks to connect two cable segments, creating a longer segment. The BNC connector is used to connect
IEEE 802.3 10Base2 coaxial cable to a hub. The BNC connector looks like a connector you would plug into your television.
Broadband Transmission Techniques used to transmit encoded signals over differing frequencies using analog signaling. See also Baseband Transmission.
Broadcast Data packets sent to all systems on a network.
Broadcast Storm Occurs when there are so many broadcast packets on the network that the capacity of the network bandwidth approaches or reaches saturation.
Brouter A brouter is a hybrid form of both a bridge and a router and has a connection to more than two networks. When the brouter receives a packet from one segment of the network, it must fi rst determine what the destination IP address is. If the packet is not destined for a port of the brouter, it sends it to the gateway address. If the packet is destined for a port of the brouter, it bridges the packet to the other port instead of routing it.
Browser (1) Application that uses HTTP to access URLs and to download and display web pages (documents that are usually written in HTML). (2) A computer that maintains a centralized list of network servers.
Browser Election The process that guarantees one and only one master browser in a workgroup or a domain subnet.
Browsing A process that enables computers on a network to fi nd each other.
BSD See Blue Screen of Death.
Buffer Space A reserved portion of RAM that provides room for the storage of incoming and outgoing data.
Bulk Encryption Key See Secret Key Cryptography.
Bus Topology A network topology that connects all computers to a single shared cable. In a bus topology, if one computer fails, the network fails. See also Star
Topology and Ring Topology.
Byte Order The order in which computers transmit larger binary numbers, consisting of two or more bytes, across a network. Computers can start at either end of a group of bytes when transmitting it across a network. See also Bit Order.
Cable Modem A network device that connects to a network or the Internet using standard TV coaxial cable.
Cache See Disk Caching.
Callback Security Security feature implemented within a Dial-In Server. When a user is confi gured to use callback and dials in to a Dial-In Server, the server disconnects the session and then calls the client back at a preset telephone number or at a number provided during the initial call.
Carrier Sense Multiple Access with Collision Detection (CSMA/CD) An access method used to submit data. To reduce collisions, CSMA /CD devices listen to the network before transmitting. If the network is .quiet. (no other devices are transmitting), the device can send its data. Because two devices can think the network is clear and start transmitting at the same time, resulting in a collision, all devices listen as they transmit. If a device detects another device transmitting at the same time, a collision occurs. The device stops transmitting and sends a signal to alert other nodes about the collision. Then, all the nodes stop transmitting and wait a random amount of time before they begin the process again.
Carrier Service Provides the transmission media. Carrier services are traditionally telephone companies.
Carrier Signal An analog signal whose characteristics.the frequency, the amplitude, and/or the phase.have been modulated to represent data.
Catalog Information describing the backup sets stored on the tape is collectively called a catalog. A catalog for a family is located on the last tape.
CAT 3 Cable CAT 3 is a grade of cable that enables networking, but CAT 5 is the better way to go. The key thing about CAT 3 is that it already exists in most offi ce buildings and homes. CAT 3 is a voice-grade cable used in phone networks. It can be used for networking up to 10 Mbps.
CAT 5 Cable Most UTP cable in today.s networks is CAT 5. CAT 5 is a standard that enables up to 100 Mbps data transmission. This is the standard UTP or STP cable type.
CDFS Read-only CD-ROM fi le system. On a CDFS volume, the fi les are burned into the volume or marked read only.
CD-ROM A device, similar to a musical compact disc, which stores data.
Cells A wireless network contains transmitters which extend a radio sphere around the transmitter.this range of coverage is called a .cell.. This cell can extend from a couple of feet to many miles.
Challenge Handshake Authentication Protocol (CHAP) An authentication protocol that uses an encryption algorithm to pass the authentication data to protect it from hackers. Because CHAP is so much more secure than PAP, it is used widely today on the Internet.
Channel Service Unit /Data Service Unit (CSU/DSU) A piece of hardware that sits between a network and a digital telephone line to translate data between the two formats. CSU/DSUs are most commonly used to attach a network router to a T1 or other digital telephone line.
Character-Based Setup The fi rst part of a Windows Server installation. During this phase, Windows Server performs an in-depth examination of your system.
Checksum A form of error checking that simply counts the number of bits sent and sends this count along. On the receiving end, the bits are once again counted and compared with the original count. If the two counts match, it is assumed the data was received correctly.
CISC See Complex Instruction Set Computing.
Class A IP Address An address class that supports 16 million hosts and has a fi rst octet that ranges between 1 and 126.
Class B IP Address An address class that supports 65,534 hosts and has a fi rst octet ranging from 128 to 191.
Class C IP Address An address class that supports 254 hosts and has a fi rst octet ranging between 192 and 223.
Class D IP address An address class used for multicasting applications. Class D addresses range from 224.0.0.0 to 239.255.255.255.
Class E IP Address An experimental address block that is reserved for future use. Class E addresses range from 240.0.0.0 to 254.255.255.255.
Client (1) The workstation accessing the resources in a client /server model. See also Client /Server Model. (2) The software that enables communications for various network services. (3) A computer that accesses resources on the network.
Client Services for NetWare (CSNW) CSNW is the client redirector that enables Microsoft workstations to interact with NetWare networks. See also
NWLink.
Client /Server Environment A client /server environment takes a centralized approach to the network operating system (NOS). If, as an administrator, you identify one machine as the network server, you can centralize network resource sharing. Clients then access the server.
Client /Server Messaging One program on one computer communicating with another program (usually on another computer).
Client /Server Model Model in which processing is requested by the client on the server. The server fulfi lls this request and sends the result back to the client.
The client requests the server to do the processing, for instance, number crunching.
Client /Server Network A network architecture, based on distributed processing, in which a client performs functions by requesting services from a server.
Coaxial (or Coax) Cable One of the three types of physical media that can be used at the OSI physical layer. A coaxial has one strand (a solid-core wire) that runs down the middle of the cable. Around that strand is insulation. There are two types of commonly used Ethernet coaxial cables: thickwire and thinwire. See also
Twisted-Pair Cable and Fiber-Optic Cable.
Command Line A character-mode interface for computer applications that relies on commands instead of a graphical interface to process information.
Complex Instruction Set Computing (CISC) Computers with processors that require large sets of processor instructions. Such processors (including
Intel 80xxx processors and most other processors on the market) use expanded instruction sets that require several execution cycles to complete. See also Reduced
Instruction Set Computing.
Compression A mathematical technique that analyzes computer fi les in order to compress them to a smaller size. Most backup systems as well as many fi le servers compress fi les to provide increased storage capacity.
Computer Bus The term used for the speed and type of interface the computer uses with different types of interface cards and equipment. The bus is actually the combination of wires, chips, and components that enables all the individual pieces to interact and make a computer what it is. The computer bus is the internal communication channel the computer uses to communicate between devices.
Different computers have different bus types.
Computer Virus A computer program built to sabotage or destroy a computer or network.
Concentrator A device that connects workstations to the path of the fi le server.
Concentrators typically have 8 to 12 ports to which workstations are attached.
Connectionless Communication A form of communication in which the destination computer does not notify the source when the information is received.
This type of communication can be unreliable, because there is no notifi cation to guarantee delivery. Connectionless communication can be faster than connection-oriented communication, because after information is sent, there is no second step to ensure proper receipt of information.
Connection-Oriented Communication Connection-oriented communication ensures reliable delivery of data from the sender to the receiver, without intervention required by either. Error correction and fl ow control are provided at various points from the source to the destination.
Container Object A container object can contain other objects and can inherit permissions from its parent container. See also Noncontainer Object and Object.
Conventional Memory The memory below 640K. If you have room, your LAN drivers are loaded in conventional memory.
Cookies Small fi les stored on the client computer that are automatically submitted to the web server for processing.
CRC See Cyclical Redundancy Check.
Cryptography See Public-Key Cryptography, Secret-Key Cryptography, and
Symmetric Cryptography.
CSMA/CD See Carrier Sense Multiple Access with Collision Detection.
CSNW See Client Services for NetWare.
CSU/DSU See Channel Service Unit /Data Service Unit.
Cyclical Redundancy Check (CRC) Form of error checking that involves running a byte or group of bytes through a mathematical algorithm to produce a single bit or byte to represent the data (a CRC). The CRC value is transmitted with the data. When the data reaches its destination, the receiver runs it through the same mathematical algorithm. The results are compared with the original CRC, and if they match, the receiving computer assumes the data are correct. If they do not match, the receiver must discard the data and try again.
DACCS See Digital Access Cross-Connect System.
Daily Backup Copies all selected fi les that have been modifi ed the day the daily backup is performed and does not mark them as having been backed up.
DAT See Digital Audio Tape.
Data Bus Pathway that carries data between the hardware components.
Data Link Control (DLC) A method that enables workstations to connect to
IBM mainframes and minicomputers in an NT environment. DLC has also been adopted by printer manufacturers to connect remote print devices to print servers, which is a second way that Windows uses DLC. Also works with Hewlett-Packard.s network-attached printers.
Data Link Layer OSI layer that handles the disassembling and the reassembling of frames on a network.
Data Terminal Equipment (DTE) Any device that converts information into digital signals for transmission and vice versa.
Database Management System (DBMS) A database environment that manages a database, including the organization, storage, security, retrieval, and integrity of data in a database.
Datagrams Used by the user datagram protocol (UDP), datagrams are self-contained, independent pieces of data that contain enough information to be routed from the source computer to the destination computer without help from either. The network uses the self-contained information of the data to determine how to send the datagram. A datagram is just like a piece of postal mail.
You drop mail in the slot, and the stamp and address are enough for the postal service to route the mail to your recipient. However, the post offi ce might lose a piece of mail, and there is no way to track when or where the mail was lost. Because datagrams use a connectionless protocol such as UDP, there is no guarantee that the datagram will reach its destination.
DBMS See Database Management System.
DECnet DECnet is a proprietary protocol developed by Digital Equipment
Corporation for use primarily in WANs. You can run DECnet on an Ethernet network, but it is done infrequently. DECnet is a routable protocol.
Default Gateway A default gateway is required when the client system needs to communicate outside its own subnet. Normally, the default gateway is a router connected to the local subnet, which enables IP packets to be passed to other network segments. If the default gateway is not confi gured in the DHCP server, it defaults to 0.0.0.0. The default gateway is needed only for systems that are part of an internetwork. Data packets with a destination IP address neither on the local subnet nor elsewhere in the routing table are automatically forwarded to the default gateway.
Demand Paging The process of bringing information from disk or memory into a working set on an as-needed basis.
Device Drivers Small programs called upon when the system needs to communicate with the various hardware components in the system.
Device Manager A confi guration tool that manages devices within Windows.
New devices can be automatically detected and installed (if they are Plug and Play compliant) or manually added (if they are not Plug and Play compliant).
Device Sharing Prevents inbound calls from going to anything but the specifi ed device. Device sharing is particularly useful in the small home offi ce where there is usually only one phone line but multiple phone-enabled devices such as phones, fax machines, or modems.
DHCP See Dynamic Host Confi guration Protocol.
Dial-Up Networking (DUN) Dialing-out service that is made available when
RAS is installed as a service. DUN enables you to connect to any dial-up server using the Point-to-Point Protocol (PPP) as a transport mechanism, enabling
TCP/IP, NetBEUI, or IPX /SPX network access over your analog modem, ISDN, or X.25 Pad devices.
Dial-Up Networking Server Enables Windows 98 to host a single dial-up network connection. Any client with support for PPP can dial in using IP, IPX, or
NetBEUI as the connection protocol. Windows 98 can then act as a server sharing its fi les and printers, just as it does on a LAN, or it can act as a gateway for an IPX or NetBEUI network.
Differential Backup Backs up only the fi les that have changed since the last full or differential backup and does not modify the archive bit. See also Full Backup.
Digital Access Cross-Connect System (DACCS) The combination of all of the T-1 and T-3 lines.
Digital Audio Tape (DAT) A hardware option for tape backup. DATs can be 4 mm or 8 mm.
Digital Linear Tape (DLT) A hardware solution for tape backup and storage that enables multiple tapes to be loaded into the system, providing unattended backups and easy access for keeping data in online storage.
Digital Voltage Meter (DVM) Used to test the continuity of a connection cable to see if there are any shorts in it.
Direct Memory Access (DMA) A process whereby some devices can directly access memory on the system without the intervention of the CPU.
Directory Number (DN) The 10-digit phone number or address the telephone company assigns to any ISDN line. Unlike analog lines, where a one-to-one relationship exists, the DN is only a logical mapping.
Directory Path The path to a directory on a fi le system, which could include the server, volume, and other names leading to the directory.
Directory Replication The process of replicating the directory database from one system to another for fault-tolerance reasons.
Directory Service A directory service is responsible for maintaining the directory of objects for an environment. Active Directory and eDirectory are examples of directory services.
Directory Synchronization The process of replicating, or synchronizing the directory database to a remote system.
Directory Tree The fi le structure, including directory and subdirectory layout below the root directory.
Discretionary Access Access control when the person who created the fi le or folder is the owner and is responsible for securing those fi les and folders.
Disk Administrator A program that creates and manages partitions.
Disk Cache Manager Manages disk caching that results in reducing the amount of I /O traffi c to the hard disk. It does this by storing frequently used data in physical memory so that it doesn.t have to be read each time from the hard disk.
Disk Caching Storing frequently used data in physical memory so that it doesn.t have to be read each time from the hard disk.
Disk Duplexing Similar to disk mirroring except that it uses two disk controller cards.one card for each drive in the mirror set. This provides redundancy in case one of the controllers fails. See also Disk Mirroring.
Disk Mirroring Provides redundancy by mirroring data from one hard drive to another. If a crash or other problem occurs on the active drive, the operating system automatically begins to use the backup drive and notifi es you of the switch.
Disk Striping with Parity See Redundant Array of Inexpensive Disks.
Diskless Workstation The diskless workstation is a concept that has been around for some time. Designed for use in fairly large environments, it originally had two goals. The fi rst was to enhance security on the network by removing local storage from the end user and requiring that all data and applications be stored on servers. By managing user access to this information via server permissions, the LAN administrator can more effectively control the environment. The second goal of diskless workstations was the cost of mass storage. By removing the cost of local storage, particularly as workstation populations increased, companies could save money. This has become less of an issue as the cost of mass storage has decreased.
Distributed Applications Applications that split processing between computers on a network, such as a client /server application, in which processing is divided between the client computer and a more powerful server computer.
Normally, the part that runs on the client computer is called the front end, and the part that runs on the server computer is called the back end.
DLC See Data Link Control.
DLL See Dynamic Link Library.
DLT See Digital Linear Tape.
DMA See Direct Memory Access.
DN See Directory Number.
DNS See Domain Name System.
Domain A group of computers containing domain controllers that share account information and have one centralized accounts database. (Not to be confused with
Internet domains, such as microsoft.com.)
Domain Controller A system that holds the Active Directory database.
Domain Model The structure of Microsoft domains and user accounts in a
Microsoft network environment.
Domain Name System (DNS) A service for mapping IP addresses to fully qualifi ed domain names. It resolves host names to IP addresses, and vice versa (with reverse lookups).
Domain Name System (DNS) Zone File The database fi le that contains all records created in the defi ned zone.
Dotted-Decimal Representation Consists of four 8-bit fi elds written in base 10, with dots (periods) separating the fi elds. Each 8-bit fi eld is represented by a number ranging from 0 to 255.
Driver A driver is a piece of the operating system that enables the operating system to communicate with the device or coordinates the communications between hardware and the computer. There are different types of drivers for modems, sound cards, and just about any other component in a computer. For example, a driver enables a LAN adapter to work.
DriveSpace A Windows 98 disk drive compression software package. With
DriveSpace, you can take all or part of a hard disk and create a new compressed drive. All data stored on the compressed drive is automatically compressed, giving you more free space.
DTE See Data Terminal Equipment.
Dumb Terminals Terminal workstations are sometimes referred to as dumb terminals. A dumb terminal is a system with no internal devices such as disks and processors. The dumb terminal has only a keyboard on which to enter information and a monitor on which typed or processed data are displayed. The data typed is sent to the terminal server and the screen information is changed, causing the new screen image to be sent to the dumb terminal, which then displays the new screen image on the monitor.
DUN See Dial-Up Networking.
Duplexing Duplexing ensures fault tolerance.not just with your data but also with your disk controller. With traditional mirroring, there is one disk controller. If the controller fails, the server is down until that component is replaced. Duplexing gives you a second controller. Each drive is connected to its own controller. If a controller fails, you still have an intact confi guration.
DVM See Digital Voltage Meter.
Dynamic Host Confi guration Protocol (DHCP) A dependable, fl exible alternative to manual TCP/IP confi guration that provides PCs with automatic confi guration of the TCP/IP parameters such as IP address, subnet mask, and default gateway.
Dynamic Link Library (DLL) A module of executable code that is loaded on demand. DLLs are used in Microsoft Windows products.
Dynamic Routing Protocols that advertise the routes they are familiar with and pass on the metrics, number of other routers, or hops required to get from their host to another network, either directly or indirectly through another router.
ECP See Extended Capabilities Port.
Edge Connector The portion of an expansion board inserted into an expansion slot when the card is seated in the computer. The number of pins as well as the width and depth of the lines differ depending on the various types of interfaces (e.g., ISA, EISA, PCI, Micro Channel).
EIDE See Enhanced IDE.
EISA See Extended Industry Standard Architecture.
Election Datagram A packet that includes that system.s browser election criteria. All current browsers and potential browsers receive the datagram. If a browser has better election criteria than it receives, it sends out its own election datagram and enters an election in progress.
Electronic Mail (email) Mail messages transmitted electronically from one network user to another, or across the Internet.
Emergency Repair Disk (ERD) Disk that can help repair Windows systems.
Emergency Startup Disk Provides a bootup option for Windows 95/98 if the server will not boot from its hard disk.
Encapsulation The process of encoding data for transmission across the network.
Encrypted Authentication Authentication of a user or other object that does not involve passing credentials in clear text. With encrypted authentication, the username and password are passed to the authentication server in an encrypted format.
Encryption An algorithm that hides the contents of a message, or other fi le or communication, by deliberately scrambling the elements that compose the item.
The item must then be decrypted to its original form before it can be read.
End-to-End Communication Communication on networks that are concerned only with the two ends of the conversation dealing with each other directly (for example, a telephone call).
Enhanced IDE (EIDE) EIDE is a disk drive interface that can support up to four 8.4-GB drives.
Environment Subsystem Provides support for the various application types that can be run, such as POSIX, Win32, and OS/2. It mimics the original environment the application expects to see.
EPROM See Erasable Programmable Read-Only Memory.
Erasable Programmable Read-Only Memory (EPROM) A set of software instructions built into the interface card to perform its functions. The software in the EPROM can sometimes be upgraded. Every interface card, whether a network card, a video card, or a sound card, comes with EPROM, which is a set of software instructions built into the interface card to perform its functions. An EPROM is sometimes fl ashable. This means that the software in the EPROM can be upgraded by downloading an update from the manufacturer and then using a utility to write the update to the fl ash memory.
ERD See Emergency Repair Disk.
Error Checking Used when sending data across a network to ensure that the data received is identical to the data that was sent originally. See also Parity Bit,
Checksum, and Cyclical Redundancy Check.
ESMTP See Simple Mail Transfer Protocol Extensions.
Establishment When a session is established, three distinct phases are involved.
In establishment the requestor initiates the service and the rules for communication are established. Once the rules are established, the data transfer phase may begin.
Both sides know how to talk to each other, the most effi cient methods, and how to detect errors, all because of the rules defi ned in the fi rst phase.
Ethernet A networking technology defi ned by the Institute of Electrical and
Electronic Engineers (IEEE) as IEEE standard 802.3. This technology is the most popular data link layer protocol because of its speed, low cost, and worldwide acceptance.
Event Logs Log fi les containing the system, security, and application events.
Executive Services Windows Executive Services (also called System Services) acts as an interface between the kernel and the environmental subsystems. It is composed of the following components: Object Manager, Security Reference
Monitor, Process Manager, Local Procedure Call Facility, Virtual Memory Manager, and I /O Manager.
Explorer The Windows shell and fi le system navigation tool.
Export Server The computer that provides the directories to be replicated with directory replication features in Windows NT. These directories are kept in the export directory located by default at %systemroot%SYSTEM32\REPL\EXPORT.
Extended Capabilities Port (ECP) Parallel port mode that provides high-speed printing and support for ECP-compliant devices.
Extended Industry Standard Architecture (EISA) A standard for the PC bus that extends the 16-bit ISA bus (AT bus) to 32 bits; it also provides bus mastering. Designed to be backward compatible with ISA devices, EISA is the data bus of choice for PC servers in non-IBM environments for high performance and throughput.
External Modem The external modem is the modem most commonly used today. Many ISPs use pools of external modems to enable dial-in access. These modems are also common in server hardware. Many IT workers include modems in production systems to allow for a backup communications link or for remote access.
External Transceiver With an external transceiver, the actual media connection is made external to the NIC using a small device that attaches to the
NIC via an extension cable. These types of connections use an Attachment Unit
Interface (AUI) connector, also called a Digital-Intel-Xerox (DIX) connector, on the back of the NIC. The AUI connector is a female 15-pin D-connector that looks very much like a joystick port. An AUI connector enables a network card to be used with multiple types of media. A common implementation is to use this confi guration for an Ethernet card that can be attached to twisted-pair, thickwire, or thinwire coax by simply changing the external transceiver type.
Family Set A family set is a collection of related tapes containing several backup sets.
FAQs See Frequently Asked Questions.
Fast Ethernet See 100BaseT.
FAT See File Allocation Table.
FAT32 See File Allocation Table 32.
Fault Tolerance The ability of ensuring that data and resources remain functional in an emergency. For example, if a cable segment breaks, traffi c will be rerouted. This fault tolerance means that the network going down due to a cable fault is almost impossible.
Fiber-Distributed Data Interface (FDDI) A high-speed token-passing network architecture that is much faster and more fault tolerant than Token Ring and can cover more distance. This technology uses fi ber-optic cabling to reach speeds of 100 Mbps. FDDI is an alternative to standard Ethernet implementations, often used as a high-speed backbone to connecting LANs.
Fiber-Optic Cable One of three types of physical media that can be used at the physical layer to carry digital data signals in the form of modulated pulses of light.
An optical fi ber consists of an extremely thin cylinder of glass, called the core, surrounded by a concentric layer of glass, known as the cladding. For most fi ber-optic cables, the conductive element is a form of special glass fi ber, rather than copper or some other conductive metal. The beauty of fi ber-optic cable is that it is immune to electronic and magnetic interference and has much more bandwidth than most electrical cable types. There are two fi bers per cable.one to transmit and one to receive. See also Coaxial Cable and Twisted-Pair Cable.
FIFO See First In, First Out.
File Allocation Table (FAT) A fi le system predominantly used for operating systems such as DOS, Windows 3.x, and Windows 95. FAT is universally accepted and accessible through other operating systems. To support backward compatibility, newer versions of Windows fully support the FAT fi le system. See also Virtual File
Allocation Table.
File Allocation Table 32 (FAT32) Windows 95 OSR2 and above support a 32-bit upgrade to the FAT fi le system that originally came from DOS. The benefi ts of FAT32 include optimal use of disk space and support for larger partition sizes over the maximum 2-GB size supported by FAT.
File and Print Server File and print servers control and share printers and large amounts of data. These servers are typically high-powered computers that are built specifi cally for the purpose of moving fi les between disk and network as quickly as possible. File and print servers also check the access control list (ACL) of each resource before enabling a user to access a fi le or use a printer. If the user or a group to which the user belongs is not listed in the ACL, the user is not allowed to use the resource.
File Server A network computer that runs the network operating system and services requests from the workstations.
File System The network operating system.s rules for handling and storing fi les.
File Transfer Protocol (FTP) A protocol designed primarily for transferring data across a network. FTP denotes both a protocol and a utility used for this purpose. It was created to quickly and effi ciently transfer data fi les from one host to another without impacting the remote hosts. resources.
Finite-State Automation (FSA) Processes status messages between each layer to coordinate communications.
Firewall Software or hardware that prevents unauthorized traffi c between two networks by examining the packets that travel on both networks. Firewalls look at the address and port information in the packet and then determine whether that type of traffi c is allowed.
Firewire An external connection standard geared toward higher-speed devices than USB. Capable of supporting videodisk players and external storage boxes, it is a very promising addition to future computers. See also USB.
First In, First Out (FIFO) The fi rst data in the buffer will be the fi rst out when the buffer becomes full.
Forest The top level of the Active Directory structure. A forest consists of one or more trees that are made up of domains. All domains in the forest share the same schema and global catalog.
Four-Octet Address The 32-bit IP address is broken into four octets that can be represented in binary (11010100 00001111 10000100 01110101) or decimal (212.15.132.117) format.
FQDN See Fully Qualifi ed Domain Name.
Fragmentation (1) Occurs when there is unused space within contiguous pages. (2) The process in which networks chop or fragment large pieces of data into more manageable units before transmission. When data are fragmented, it is important to ensure that all the pieces make it to the other end in the right sequence. If they are not in order, it is sometimes possible to re-sequence the data into the right order.
Frame Relay A packet-switched protocol.
Frequently Asked Questions (FAQs) Appear in specifi c areas of bulletin boards and web sites and contain answers to frequently asked questions about a product or service. FAQs are used in newsgroups to cover questions that have appeared often.
FSA See Finite-State Automation.
FTP See File Transfer Protocol.
Full Backup Backs up every fi le on the specifi ed volume or volumes. Full backups should be run frequently, and at least one current copy should be stored offsite.
Full-Duplex Dialogs Used by OSI session layer to enable data to fl ow in both directions simultaneously.
Full Synchronization In a full synchronization, the PDC sends a copy of the entire directory service database to a BDC.
Fully Qualifi ed Domain Name (FQDN) The complete DNS namespace path to a computer is known as a FQDN.
Gateway A device or service that translates data from one format to another.
GDI See Graphics Device Interface.
Gigabit Network Gigabit networks operate at 1000 Mbps, or 1 gigabit per second (Gbps). This is sometimes known as .gigabit to the desktop. and is extremely expensive to implement for large networks. This type of cabling is usually employed only as a backbone between buildings if Fast Ethernet connection between the buildings might cause a bottleneck.
Gigabyte (GB) The equivalent of one billion bytes.
Global Groups Created on domain controllers and used to organize the users.
Graphics Device Interface (GDI) Graphics engine that controls the display of graphics on the monitor and printers. It is responsible for communication between applications and the graphics devices.
Group Accounts Accounts used for grouping users who perform the same function or require access to the same resources. If it were not for group accounts, you would have to grant access to resources on a per-user basis.
Groupware Any software that enhances a group.s capability to collaborate in the performance of a task.
Guest Account Used for limited access for remote users or users from other domains. Disabled by default, the guest account provides low-level access to the computer for users that do not have a user account of their own.
Half-Duplex Dialogs Used by the OSI session layer to enable data to fl ow in two directions, but only one direction at a time. With half-duplex dialogs, replies and acknowledgments are possible.
Handshaking Connection-oriented services must ensure that data is sent reliably across the network. Handshaking takes place at the beginning of a communication session. During handshaking, the two computers determine the rules for communication, such as transmission speed and which ports to use.
Handshaking also determines the proper way to terminate the session when fi nished.
This ensures that communication ends in an orderly manner.
Hardware Compatibility List (HCL) A list composed of hardware devices that have been tested for compatibility with a given operating system.
Hardware Profi le An alternative confi guration you can select from a startup to specify various options. Laptop users employ one hardware profi le for the docked confi guration and another for the undocked, or travel, confi guration.
HCL See Hardware Compatibility List.
HDLC See High-level Data-Link Control.
Heterogeneous A mixed networking environment involving different operating systems such as Windows, UNIX, Novell NetWare, and networking protocols and hardware platforms.
High-Level Data-Link Control (HDLC) Protocol used to encapsulate the data stream as it passes through the PPP connection.
Home Directory An option for a user account that can give the user an accessible place to store fi les.
Host A system or device that participates on the network.
Host ID The portion of the 32-bit address that identifi es the device on a TCP/IP network.
Hosts File In early TCP/IP networks, all known hostnames and their associated
IP addresses were stored in a simple text fi le called hosts. In most UNIX installations, the hosts fi le is located in the /etc directory and is also commonly referred to as /etc /HOSTS. The hosts fi le contained one line for each IP address and at least one associated name. The hosts fi le design allowed multiple names for the same IP address. Therefore, hosts contains mappings of remote hostnames to IP addresses. The hosts fi le provides a static lookup of a hostname for the associated IP address. Notice also that the hosts fi le is fl exible in that multiple names can be associated with one IP address.
Hot-Swappable Parts Parts that can be replaced without shutting down the system.
HTTP See Hypertext Transfer Protocol.
HTTPS See Hypertext Transfer Protocol, Secure.
Hub The device used in a star topology that connects the computers to the LAN.
Hubs can be passive or active. See also Active Hub; Hybrid Hub; Passive Hub.
Hybrid Hub A hybrid hub is a hub that can use many different types of cables.
For example, a hybrid hub may have a number of UTP ports and a connector for coax.
Hypertext Transfer Protocol (HTTP) HTTP is the protocol used on the
Internet to allow clients to request web pages from web servers and allow for client interaction with those web servers. HTTP is a stateless protocol, meaning that the web servers are not aware of what a client has or has not requested and cannot track users who have requested specifi c content. This system does not allow for good interaction with the web server but does allow for retrieving the HTML pages stored on web sites.
Hypertext Transfer Protocol, Secure (HTTPS) HTTPS allows you to connect to a web site and receive and send content in an encrypted format using
Secure Sockets Layer (SSL). HTTPS is most commonly used on e-commerce sites to allow you to send you personal information without worrying that an Internet hacker is viewing this information, especially credit card numbers and other confi dential data. You can determine when HTTPS is being used because the address of the Web site starts with https:// and not http://, which is the regular
HTTP protocol. Another sign that HTTPS is in use: In Internet Explorer, a lock appears in the status bar of a page; the lock is either closed or locked. HTTPS is not used for an entire e-commerce site because the encryption and decryption processes slow the connection time; consequently, only pages containing personal information use HTTPS.
ICMP See Internet Control Message Protocol.
IDE See Enhanced IDE; Integrated Drive Electronics.
IETF See Internet Engineering Task Force.
IEEE See Institute of Electrical and Electronics Engineers.
IIS See Internet Information Service.
IMAP See Internet Message Access Protocol.
Impersonation Technique for a server process to access objects that it doesn.t have permissions to. If the client process has proper access permissions, the server process impersonates the client process in order to access the object.
Import Computer A system that receive the replicated fi les and directories from the export server with Windows NT.s directory replication feature. The directories are kept in an import directory located by default at systemroot%SYSTEM32\
REPL\IMPORT.
Incremental Backup Backs up all the fi les that have been changed since the last backup and clears the archive bit.
Industry Standard Architecture (ISA) An older bus architecture that supported 16-bit cards and ran at 8 MHz.
Information Store One of the four core components of Microsoft Exchange
Server. The Information Store consists of two databases, the public Information
Store (pub.edb) and the private Information Store (priv.edb). This is where all electronic messages are stored.
Inherited Permission Permissions inherited from the parent folder for a fi le or folder.
Input /Output (I/O) Addresses Spaces in memory designated for a device.s own use.
Input /Output (I/O) Base Address The I /O base address is the starting address for a series of registers used to control the card. A common I /O address for a network card is 300h. Care must be taken to ensure that this address is not already in use by another device, or the adapter will fail.
Input /Output (I/O) Manager Part of the Windows Executive Services, responsible for all input and output for the operating system.
Institute of Electrical and Electronics Engineers (IEEE) A large and respected professional organization that is also active in defi ning standards.
Institute of Electrical and Electronics Engineers (IEEE) 802.2 The LLC sublayer is used by other protocols defi ned by the 802 committee. This sublayer allows network-layer protocols to be designed separately from the low-level physical-layer and MAC sublayer protocols. The LLC adds header information that identifi es the upper-layer protocols sending the frame. The header can also specify destination processes for the data.
Institute of Electrical and Electronics Engineers (IEEE) 802.3 The IEEE standard that defi nes CSMA /CD, or the Ethernet architecture.
Institute of Electrical and Electronics Engineers (IEEE) 802.5 The IEEE standard that defi nes Token Ring.
Institute of Electrical and Electronics Engineers (IEEE) 802.11 The IEEE 802.11 standard addresses wireless networking. This standard includes the WAP devices and the wireless NICs that are used to send and receive broadcasts from the cell or WAP device. The WAPs and wireless NICs can be set to use different frequencies to allow for cell overlap. This technology does not include the technology used by cell phones to manage movement of PCs or mobile devices. The wireless NIC is set to a specifi c frequency and must be changed manually in order to communicate with another cell. This means that a PC cannot be moved from one cell area to another without changing frequency, unless for some reason the cells operate on the same frequency and have no overlap of coverage area.
Institute of Electrical and Electronics Engineers (IEEE) 802.1x A wireless authentication standard that uses external authentication services such as
RADIUS.
Integrated Drive Electronics (IDE) One of two common interface types in tape drives and hard drives. IDE is mainly used in the slower and lower-capacity
QIC-style tape drives. See also Enhanced IDE; SCSI.
Integrated Services Digital Network (ISDN) Connections that take place over digital lines and provide faster and more reliable connectivity. The primary benefi t of ISDN is its speed and reliability. ISDN is commonly found in two speeds: 64 Kbps and 128 Kbps.
Interactive Mode Interactive mode is used when you have more than one item in the DNS database you will be querying. Interactive mode allows you to enter a command-line state that will keep prompting you for more commands until you type
Exit at the NSLOOKUP command prompt to return to a standard DOS command prompt and exit the NSLOOKUP utility.
Interference Noise that disturbs the electrical signals sent across network cables.
Internal Modem A modem that is installed into the system, usually in the form of a PCI card.
Internet Control Message Protocol (ICMP) ICMP is the protocol in TCP/IP that enables systems on a TCP/IP network to share status and error information.
Internet Engineering Task Force (IETF) Group responsible for the operation, management, and evolution of the Internet. The steering committee of the IETF is known as the Internet Engineering Steering Group (IESG).
Internet Explorer See Microsoft Internet Explorer.
Internet Information Service (IIS) Microsoft.s web server product. IIS provides full-featured SMTP server, FTP Server, and an HTTP Server.
Internet Layer TCP/IP layer that is responsible for handling the communication from one computer to another computer. It accepts a request to send data from the transport layer. The Internet layer consists of two protocols, the Internet Protocol (IP) and the Internet Control Message Protocol (ICMP).
Internet Message Access Protocol (IMAP) IMAP is another protocol similar to POP that allows clients to retrieve messages from a mail server. (IMAP is on its fourth iteration, IMAP4.) IMAP allows email retrieval for the purpose of storing the mail somewhere other than on the mail server. IMAP can be used with Microsoft
Outlook to retrieve email and store it in a data fi le on the local PC.
Internet Network Information Center (InterNIC) The central authority responsible for issuing all network IDs that will be used on the Internet. InterNIC operates under contract with the National Science Foundation (NSF).
Internet News Service A service that enables an older version of Exchange to participate in USENET newsgroups. Newer versions of Exchange support the NNTP protocol.
Internet Protocol (IP) A common protocol that sets up the mechanism for transferring data across the network. Provides packet delivery for all other protocols within the TCP/IP suite.
Internet Protocol (IP) Address Uniquely identifi es a computer on the network. It is 32 bits long, with four octets separated by dots. This number is then converted to binary and used as a unique identifi er.
Internet Protocol CONFIG (IPCONFIG) A command-line tool to view and troubleshoot TCP/IP settings. See also WINIPCFG.
Internetwork Packet Exchange (IPX) The native transport protocol for
Novell.s NetWare. IPX is also available in the Windows environment.
Internetwork Packet Exchange/Sequenced Packet Exchange (IPX/SPX)
A protocol that was primarily used by Novell NetWare networks, but can also be used by other networks (such as Microsoft networks) as a routable protocol or to connect to Novell networks.
Internetworks A network of networks, such as the Internet. Repeaters, bridges, and routers are devices used to link individual LANs together to form larger internetworks. See also Bridges, Repeaters, and Routers.
InterNIC See Internet Network Information Center.
Interprocess Communications (IPC) Methods of communication between one program and another. Depending on the IPC method being used, this communication can even be across a network. IPC is often used in the client /server environment as a means of communication between the server and the client across the network.
Interrupt Request (IRQ) Used by the device to interrupt the processor and request service.
Interrupt Request (IRQ) Lines Hardware lines over which devices send interrupt signals to the microprocessor.
Intersite Communication Communication that uses messaging connectors to connect two Exchange sites.
Intrasite Communication Communication that takes place among servers in the same Exchange site. Intrasite server communication uses Remote Procedure
Calls. RPCs can be used over several protocols, including IPX /SPX, TCP/IP, and
NetBEUI.
I/O See Input /Output.
IP See Internet Protocol.
IPC See Interprocess Communications.
IPCONFIG See Internet Protocol CONFIG.
IPX See Internetwork Packet Exchange.
IPX/SPX See Internetwork Packet Exchange/Sequenced Packet Exchange.
IRQ See Interrupt Request.
ISA See Industry Standard Architecture.
ISDN See Integrated Services Digital Network.
Jetpack Windows Server utility that can be used to compact a WINS or DHCP database.
Jumper A jumper is a plastic piece with metal inside that connects two metal posts on the card to complete a circuit.
Kilobits per Second ( Kbps) A data transfer speed of 1024 bits per second.
Kernel Also called microkernel, it refers to the core code in an operating system.
This is the most important part of the operating system and is responsible for all functions on the system, such as creating, managing, and scheduling threads.
Kernel Mode Also called Privileged Mode, the Kernel Mode has direct access to the hardware. Some components of Windows that used to run as User Mode components now run as Kernel Mode components. These are the Window Manager,
GDI, and graphics device drivers.
Key Management Server An integrated component within older versions of
Exchange Server. It is used to provide advanced security to an Exchange Server organization. The Key Management Server uses public-key cryptography and secret-key cryptography.
Lag The slowing of network performance usually caused by increased demand for available bandwidth.
LAN See Local Area Network.
LastKnownGood The confi guration that was saved to a special control set in the
Registry after the last successful logon to Windows.
LCP See Link Control Protocol.
Lease Duration The lease duration specifi es how long a DHCP client can use an
IP address before it must renew it with the DHCP server. This duration can be set for an unlimited time period or for a predetermined time period. You have the option of confi guring a scope to reserve a specifi c IP address for a DHCP client or even for a system on the network that is not DHCP enabled.
Least Signifi cant Bit When a computer starts reading at the last digit of a binary number, it is using the least signifi cant digit. When a computer starts with the fi rst digit, it is using the most signifi cant digit.
Legacy System An existing system that either needs updating or is no longer capable of maintaining required performance.
Link Control Protocol (LCP) Used by PPP to establish, test, and confi gure the data link connection.
LLC See Logical Link Control.
LMHOSTS File A text fi le that resides on the hard drive of the client and helps map NetBIOS names to IP addresses.
Load The amount of data present on the network. Also known as network traffi c.
Local Area Network (LAN) Consists of any two or more computers joined to communicate within a small area, usually not larger than a single building. See also
Virtual Local Area Network.
Local Area Network (LAN) Driver Provides the software to enable the NIC to communicate with the network.
Local Groups Groups located in the local SAM database of a Windows system that are used to assign permission to resources on that system.
Local Procedure Call Facility Responsible for passing information between processes.
Local Security Authority The heart of the Windows security subsystem. It creates security access tokens, authenticates users, and manages the local security policy.
Log Off (or Log Out) The procedure for terminating your session with the system.
Log On (or Log In) The procedure for checking in to the network so that you can access fi les and other network information. When you have access to the network, you are said to be logged on.
Logical Link Control (LLC) The 802 model breaks the data link layer into two sublayers: Logical Link Control (LLC) and Media Access Control (MAC). The LLC layer starts and maintains connections between devices. When you send data from your workstation to a server on the same network segment, it is the LLC sublayer that establishes a connection with that server.
Logon Scripts Used to start applications, map network drives, or set environment variables when the user logs onto the network.
Long File Name Capability Frees you from the restrictive 8.3-naming scheme that was a part of DOS and older versions of Windows. With longer fi le names, you can adopt a more descriptive naming scheme.
Loopback Address Any address that starts with 127.x.x.x and is used to verify that the TCP/IP software stack has been loaded and is functional on the system.
Loopback Test A test that verifi es that the TCP/IP stack was installed correctly and is working. A stream of data is sent out and loops back around into the card.
The data is then compared to determine whether the data received is the same as the data that was sent.
Loose Source Routing An additional tracert option. The -j option can be used to force the outbound datagram to pass through a specifi c router and back.
This enables you to trace the round-trip route for a destination. A normal tracert follows the route until it reaches its destination or times out. When you specify this option, tracert follows the path to the router specifi ed and returns to your computer.
MAC See Media Access Control.
Mail Client Software application that retrieves the messages from the mailbox and, in most cases, deletes them from the mailbox. In addition, most mail clients enable you to send outgoing email, and have some type of message decoding built in.
Some popular mail clients include Microsoft Outlook, Eudora, and Pegasus.
Mail Routing Mail transfer from one location to another.
Mailslot Mailslots are an easy way for one computer to send information to many clients. A server can open a mailslot and write data to it. Other computers on the network can connect to the mailslot and read from it. The server sends the information out from the mailslot, but cannot be sure who is listening. A mailslot is much like a bulletin board. Anyone can post a note to it and walk away, and anyone can read the note; you just don.t know how many people might have seen it.
Management Information Base (MIB) Defi nes management objects for a network device.
Mandatory Logon Windows uses mandatory logon to force users to log on before it grants access to the system.
Master Domain Model All user accounts are located in a single domain called the master domain. Resources, such as printers and fi les, are shared in other domains called resource domains. This model allows for centralized administration.
MAU See Multistation Access Unit.
Maximum Port Speed Defi ned by the kilobytes per second that the modem can support. Maximum rates are defi ned primarily by the modem hardware; however, the current public telephone network has an upper limit of 56 Kbps through an analog modem.
MCA See Microchannel Architecture.
Media Access Card See Network Interface Card.
Media Access Control (MAC) The MAC layer is a sublayer of the data link layer and determines which computer may speak and when.
Media Access Layer Address The media access layer address, or hardware address, is a 12-digit hexadecimal number consisting of digits 0 through 9 and letters
A through F. It is a hexadecimal number assigned to the network card. The address consists of two pieces: The fi rst signifi es the vendor it comes from, the second is the serial number unique to that card. For the exam you will not need to know how these numbers break down; you just need to know what the address is.
Media Filter Used on Token Ring networks to change the type of media from Type 1 (shielded twisted pair) to Type 3 (unshielded twisted pair) or vice versa.
Megabits per Second ( Mbps) Used to measure throughput or communication speed. Mbps is a communications rate of 1,048,576 bits per second.
Member Server A Windows server that is part of the domain and does not have
Active Directory installed.
Memory Physical memory is RAM (random-access memory); virtual memory is hard disk space acting as though it were additional RAM.
Mesh Topology In a mesh topology, every workstation has a connection to every other component of the network.
Message Transfer Agent (MTA) A core component of a mail server. The MTA is responsible for delivering messages between servers.
Metropolitan Area Network (MAN) The term metropolitan area network is not often used any more; it refers to a network that spans a single city or metropolitan area.
MIB See Management Information Base.
Microchannel Architecture (MCA) The 32-bit data bus released by IBM in 1988 with IBM.s PS/2 product line. MCA was a totally new architecture that was not backward compatible with ISA cards. MCA adapters are more expensive and offer higher performance than the ISA adapters.
Microsoft Backup Microsoft utility for backing up and restoring fi les from your hard disk to both removable and nonremovable disks and tapes.
Microsoft Batch 98 The program created by Microsoft to help create the fi les required for Windows 98 automated setup. Microsoft Batch 98 is included in the
Windows 98 Resource Kit.
Microsoft Challenge Handshake Authentication Protocol (MS-CHAP)
A form of the Challenge Handshake Authentication Protocol. It uses the same type of encryption methodology but is slightly more secure. The server sends a challenge to the originating host, which must return the user name and an MD-4 hash of the challenge string, the session ID, and the MD-4 hashed password.
Microsoft Exchange Server Microsoft.s messaging and collaboration product.
Exchange supports Internet protocols such as SMTP, NNTP, POP3, IMAP4, and
MAPI.
Microsoft Infrared In Windows 9x, a wireless transmission used for network connectivity and for printing to infrared-ready printers. Infrared devices can now be used in Windows 9x just like devices that are normally connected directly with a cable.
Microsoft Internet Explorer (IE or MSIE) Microsoft.s Web browser.
Windows 98 integrates IE into the desktop.
Microsoft Proxy Server Proxy Server enables a single connection to the
Internet to be shared by many users, enabling outbound FTP and web access (and other supported TCP/IP ports). Proxy Server accomplishes this by making requests for Internet resources on behalf of users so that only a single TCP/IP address appears to be initiating Internet access.
Microsoft System Information (MSI) A utility that provides easy read-only access to detailed information regarding the Windows 98 operating system, computer hardware, and even third-party software.
MIME See Multipurpose Internet Mail Extension.
Mirroring Duplicating information to another hard disk. If one hard drive fails, the other hard drive is immediately available with the very same information.
MODEM See Modulator/Demodulator.
Modulator/Demodulator (MODEM) A device used to translate digital signals from the computer into analog signals that can travel across a telephone line. Also known as data circuit-terminating equipment. See also Analog Modem; External
Modem; Internal Modem; Unimodem.
Most Signifi cant Bit When a computer starts reading the fi rst digit of a binary number, on the far left, it is using the most signifi cant bit. When a computer starts reading the last digit, on the far right, it is using the least signifi cant digit. Also, known as the high order bit.
MS-CHAP See Microsoft Challenge Handshake Authentication Protocol.
MSI See Microsoft System Information.
MSIE See Microsoft Internet Explorer.
MTA See Message Transfer Agent.
Multi-Homed System Refers to a computer that is confi gured with more than one network adapter.
Multilink Channel Aggregation Feature of Windows that multiplies the total bandwidth between the remote PC and the host by combining two or more modem or ISDN lines. The only issue with using this technology is that there must be a separate telephone or ISDN line for each modem or ISDN device that is used.
Multi-Modem Adapters with Windows Server (Multilink) Combines two or more physical links, most commonly analog modems, into a logical bundle, which acts as a single connection to increase the available bandwidth and speed of the link.
Multiple Master Domain Model Managed much like the master domain model, except it can handle more users. The multiple master domain is actually two or more master domain models joined by a two-way trusts.
Multiport Bridge See Switch.
Multiprocessing Capability of the system to increase processing power by adding more processors. See also Symmetric Multiprocessing.
Multipurpose Internet Mail Extension (MIME) See Non-MIME.
Multipurpose Internet Mail Extension (MIME) Attachment A type of
Internet message. MIME messages are made up of headers and bodies. MIME is the standard method of sending and receiving messages across the Internet, regardless of mail server type.
Multistation Access Unit (MAU) A central hub in a Token Ring LAN.
Multitasking The capability to run several applications at once.
Multi-Vendor Gateways Provide a translation method between one type of mailbox server to another type of mail client. The gateway enables clients such as
Microsoft Outlook to read data from hosts that are not the same as Outlook.
NAT See Network Address Translation.
NBTSTAT A utility used to troubleshoot name resolution between NetBIOS names and the IP address.
NCP See NetWare Core Protocol.
NDIS See Network Driver Interface Specifi cation.
NDS See Novell Directory Services.
Near-Line Backups These backups differ from offl ine backups in that they are kept on devices connected to the network for faster restoration of fi les. They require more effort to restore than accessing a fi le from a hard disk, but less effort than restoring a fi le from an offl ine backup.
NetBIOS Extended User Interface (NetBEUI) A nonroutable transport layer protocol used on a number of operating systems prior to Windows 2000.
NetBIOS See Network Basic Input /Output System.
NetBT NetBIOS over TCP/IP. A software standard and naming convention to use NetBIOS services over the TCP/IP protocol.
NETSTAT A TCP/IP utility for relating protocol statistics and current active connections.
NetWare Novell.s network operating system.
NetWare Connect (NRN) Used to connect to NetWare services via IPX /SPX.
NetWare Core Protocol (NCP) The core protocol used in NetWare for accessing shared resources on the server.
NetWare Directory Services (NDS) Novell.s directory services with
NetWare 4.x and 5.x.
Network Two or more computers linked so that they can communicate.
Network Adapter See Network Interface Card.
Network Address Translation (NAT) NAT is a service that allows requests from private addresses to be translated to a public address, thus hiding internal network resources.
Network Basic Input /Output System (NetBIOS) A networked extension to PC BIOS. NetBIOS enables I /O requests to be sent and received from a remote computer. Commonly called an application program interface (API).
Network Driver Interface Specifi cation (NDIS) A network device driver specifi cation, NDIS provides hardware and protocol independence for network drivers. A benefi t of NDIS is that it offers protocol multiplexing, which enables multiple protocol stacks to coexist in the same host.
Network Dynamic Data Exchange (NetDDE) Enables two applications to communicate, with a link always maintained.
Network File System (NFS) A UNIX protocol for fi le sharing that enables a user to use network disks as though they were connected to the local machine.
Network Infrastructure The physical equipment that hooks computers into a network. This includes the cables, hubs, routers, and software used to control a network.
Network Interface Card (NIC) Also called an adapter card, interface card, or media access card. It is installed in a computer to enable it to communicate with other computers over a network. A NIC changes the parallel signals inside the computer into serial signals that go over the network cable.
Network Interface Layer The lowest level in the TCP/IP model. It accepts the datagram from the Internet layer and transmits it over the network.
Network Layer Layer 3 of the OSI model, responsible for logical addressing and routing.
Network Map A detailed map of what.s on the network. Includes an inventory of machines and other hardware, a map of cable layout, and other information to document the network.
Network Monitor A Windows tool that .sniffs out. packets on the network and helps diagnose any problems concerning protocols.
Network Neighborhood An application available from the Windows 95, 98, and NT desktops that enables you to view computers in a workgroup or domain and to access the resources they are sharing. This icon has been replaced by My Network
Places in Windows 2000/XP.
Network News Transfer Protocol (NNTP) NNTP is used to send and retrieve news articles or news feeds on the Internet in newsgroups.
Network Operating System (NOS) An operating system that permits and facilitates the networking of computers. Manages and controls access to shared resources such as printers and folders on the server. Popular examples of a network operating systems are Novell Netware, Windows 2003, and Linux.
Network Segmentation A bridge is a simple way to accomplish network segmentation. Placing a bridge between two different segments of the network decreases the amount of traffi c on each of the local networks. Although this does accomplish network segmentation, most network administrators opt to use routers or switches. Bridges segment the network by MAC addresses. When one of the workstations connected to Network 1 transmits a packet, the packet is copied across the bridge as long as the packet.s destination is not on Network 1. A bridge uses a bridge routing table to calculate which MAC addresses are on which network.
Network Terminator 1 (NT1) Device located at the end-user side of the ISDN connection.
Network Terminator 2 (NT2) Placed between an NT1 device and any adapters or terminal equipment.
Network Time Protocol (NTP) Used to synchronize the clocks of PCs on a network or Internet. This is accomplished by confi guring a server to be the time server, which then is the server from which all other PCs on the network synchronize their time.
New Technology DETECT (NTDETECT) The hardware recognition program used by the Windows operating system during the bootup process.
New Technology File System (NTFS) A secure fi le system developed for
Windows. NTFS is transaction orientated, enables permissions to be assigned to both fi les and directories, and has the capability to compress fi les. It can be read only by Windows NT based operating systems such as Windows 2000, XP, and 2003.
New Technology Virtual DOS Machine (NTVDM) A 32-bit application run in a separate memory space that is capable of being multitasked with other applications (thereby increasing performance). This process runs DOS applications and 16-bit Windows applications.
Newsfeeds See Pull Feed; Push Feed.
NFS See Network File System.
NIC See Network Interface Card.
NNTP See Network News Transfer Protocol.
Node Each device on a network is an individual node. It can be a workstation, a printer, a router, or a fi le server.
Noncontainer Object A noncontainer object doesn.t contain other objects.
See also Container Object and Object.
Non-MIME A type of Internet message usually encoded as BINHEX or
UUENCODE. These are both older standards used to send binary images over the
Internet. They still are the method of choice with Internet POP clients such as
Eudora and most Macintosh mail readers.
Normal Backup A normal backup, also called full backup, copies all selected fi les and marks each fi le as having been backed up. With this type of backup, you can restore fi les easily because the most current fi les will be on the last tape.
NOS See Network Operating System.
NRN See NetWare Connect.
NSLOOKUP The NSLOOKUP command is a TCP/IP utility used to troubleshoot DNS name resolution problems.
NT See Network Terminator.
NTDETECT See New Technology DETECT.
NTFS See New Technology File System.
NTP See Network Time Protocol.
NTVDM See New Technology Virtual DOS Machine.
NWLink Microsoft.s implementation of Novell.s IPX /SPX protocol suite.
NWLink is a routable transport protocol for Microsoft networks and for connecting to NetWare networks through CSNW or GSNW. See also CSNW.
Object In Windows, just about everything is an object. A fi le is an object and so is a window. Objects have a type, various attributes, and a set of operations. They can be physical devices (such as a COM port) or they can be abstract (such as a thread). Windows controls access to objects. See also Container object and
Noncontainer object.
Object Manager Responsible for the creation and use of objects, including the naming, managing, and security for objects.
Offl ine Backups Backups that are kept offl ine. They are removed from the operation of the server and require the medium, usually tape, to be loaded in order to restore.
Offl ine Storage Tape backups are called offl ine storage, which means the data are copied to tape cartridges stored external to the computer and the data are not readily accessible. The data must be copied from the tapes back to the hard disk to be accessible.
Offsite Storage A place in a separate location from the fi le server, used to store backup tapes. A complete backup should always be kept off site.
Onboard Transceiver Onboard transceivers are transceivers built onto the network interface card.
Online Backups Backups that are stored online so that they are immediately available.
Open Protocol Standards Nonproprietary. For example, because TCP/IP is not tied to an operating system, any vendor developing a new operating system with a network component can refer to the RFCs to build a TCP/IP component.
Open Systems Interconnect (OSI) The Open Systems Interconnect (OSI) model is a group of standards for network hardware and software . This is the most common network model used in PC networks and consists of seven layers: application, presentation, session, transport, network, data link, and physical.
OSI See Open Systems Interconnect.
Outlook Web Access Client A web based application that allows users to view their Exchange mailbox data from a web browser.
Overhead The control attached to packets transmitted across a network.
Overhead data includes routing and error-checking information. Overhead also refers to the bandwidth used to sustain network communications.
Packet Small, manageable pieces of data that are transmitted over the network as a whole. The packet must include a header section, a data section, and, in most cases, a cyclic redundancy check (CRC) section, also called a trailer.
Packet Burst Used with IPX when a packet burst-enabled source sends multiple packets across a network without waiting for an acknowledgment for each packet.
Instead, one acknowledgment is sent for the group of packets.
Packet Internet Groper (PING) Utility for verifying IP-level connectivity.
Page The size of the smallest portion of memory that can be managed, which is 4 KB.
Paging File A fi le used by Windows to move an unused portion of memory to the hard disk and to retrieve the data when it is needed. The paging fi le is actually a fi le called PAGEFILE.SYS; by default it is located in the root directory of the drive you specify in the Virtual Memory dialog box.
PAP See Password Authentication Protocol.
Parity Bit A basic method of checking for errors with transmitted data. Before sending data, the number of individual bits that make up the data are counted. If there are an even number of bits, a parity bit is set to one and added to the end of the data so that the total of the bits being sent is odd. If there are an odd number of bits, the parity bit is set to zero and added to the end. The receiving computer adds up the bits received, and if there are an even number of bits, the computer assumes that an error has occurred. The parity method is not foolproof, because if an even number of bits is corrupted, they will offset each other in the total.
Partial Synchronization The automatic, timed replication to all domain controllers of only those directory database changes that have occurred since the last synchronization.
Partition A logical division of a physical disk that is treated as though it were a separate hard disk. After partitioning the hard disk, you need to decide which partition will be the system partition and which will be the active partition. See also
Active Partition and System Partition.
Passive Hub A hub device used in a star topology that connects machines to the network and organizes the cables, but does not regenerate the signal.
Passive Topology A bus is a passive topology. That means that the computers on a bus topology only listen or send data. They do not re-send or regenerate data.
Consequently, if one computer on the network fails, the network is still up.
Pass-Through Authentication Occurs when your credentials are not in the local directory service database.
Password The key to access the network during logon.
Password Authentication Protocol (PAP) An authentication protocol in which the client authenticates itself to a server by passing the username and password to it. The server then compares this information to its password store.
Because the password is passed in clear text, this is not recommended in an environment where security concerns are an issue.
PC A computer designed for individual use.
PCI See Peripheral Component Interconnect.
PCMCIA See Personal Computer Card Bus.
PDC See Primary Domain Controller.
Peer Resource Sharing In Windows 9x, the capability to simulate a server by sharing its fi les, drives, and printers across a network.
Peer-to-Peer Environment Each workstation on the network is equally responsible for managing resources and can share its resources with other systems on the network.
Peer-to-Peer Network See Peer-to-Peer Environment.
Peer Web Services A scaled-down version of the Internet Information Server (IIS) that enables you to publish web pages on a Windows 95 computer.
Performance Monitor A utility that tracks the usage of resources by the system components and applications and provides performance information about the network to help locate bottlenecks, determine which resources are too taxed, and plan upgrades to the system.s capacity.
Performance Tuning The art of maximizing the performance of an existing confi guration to achieve the optimal outcome.
Peripheral Component Interconnect (PCI) A 32-bit bus architecture that runs at 33MHz.
Permissions Permissions are assigned to users on a resource such as fi le or printer.
A permission decides on someone.s level of access to that resource.
Personal Computer (PC) Card Bus The bus architecture used in laptops to expand the computer.s capabilities. PC card bus is also known as PCMCIA; it runs at 33 MHz and is 16 bit.
Phonebook Entry Stores the confi guration information required to connect to a remote network. Entries are stored as individual dial-up connections in a phonebook fi le.
Physical Layer Bottom layer of the OSI model that is concerned only with moving bits of data on and off the network medium.
PING See Packet Internet Groper.
Plain Old Telephone Service (POTS) The standard analog telephone system, such as the one used in most houses.
Platform A type of computer system. For example, Intel x86 and UNIX are platforms.
Plug and Play With the introduction of Windows 95 came the Plug and Play operating system. Plug and Play has been around for a while. The Plug and Play operating system and the Plug and Play BIOS work hand in hand to confi gure expansion components such as NICs. The premise behind Plug and Play software is to make confi guration by the end user minimal if not nonexistent.
Point-to-Point Protocol (PPP) A serial protocol used for sending information over a dial-up connection. This protocol enables the sending of IP packets, supports compression, enables IP address negotiation, and is the successor to the older SLIP protocol.
Point-to-Point Protocol Multilink Protocol (PPP-MP) Protocol used to enable multiple ISDN devices or multiple modems using separate phone lines to aggregate their bandwidth. By using two or more devices for a single dial-up link, the bandwidth of the devices is combined, thereby increasing the total bandwidth.
Point-to-Point Transmission (PPT) Many computer networks use point-topoint transmission methods, where there may be one to dozens of points between the source and the destination of a message. (Email is a good example of this.)
Each point is concerned only with transferring data to the next point downstream.
Point-to-Point Tunneling Protocol (PPTP) An Internet standard enabling multiple protocols, such as NetBEUI and IPX, to be encapsulated within IP datagrams and transmitted over public backbones such as the Internet. PPTP enables the secure transfer of data from a remote client to a private server by creating a multi-protocol virtual private network (VPN).
POP See Post Offi ce Protocol.
Port Numbers Preassigned TCP/IP port numbers on the server (although they can be changed). They are preassigned so they can expect traffi c on a corresponding port relating to the service that is using that port. Values less than 1026 are known as .well-known ports..
Portability The capability of a system, such as Windows NT, to be ported to other hardware platforms.
Portable Operating System Interface (POSIX) A standard developed by the Institute of Electrical and Electronic Engineers (IEEE) for fi le naming and identifi cation based on UNIX. In order to be POSIX-compliant, the software must fulfi ll certain requirements, such as case-sensitive fi lenames, hard links, and additional time stamping.
POSIX See Portable Operating System Interface.
Post Offi ce Protocol (POP) POP is the protocol for downloading mail from the mail server to the client. A POP3 mail server holds the mail in a maildrop until the workstation is ready to receive the mail.
POTS See Plain Old Telephone Service.
PPP See Point-to-Point Protocol.
PPP-MP See Point-to-Point Protocol Multilink Protocol.
PPT See Point-to-Point Transmission.
PPTP See Point-to-Point Tunneling Protocol.
Preemptive Multitasking A method of multitasking that has the capability to prioritize the order of process execution and preempt one process with another.
Presentation Layer OSI layer that ensures that data sent by the application layer and received by the session layer is in a standard format. If it is not, the presentation layer converts the data.
Primary Domain Controller (PDC) The NT Server maintaining the master copy of the directory service database for the domain. It handles synchronization with the Backup Domain Controllers.
Print Device The actual hardware that prints the document. The three basic types of print devices are raster, PostScript, and plotter.
Print Driver The software that enables an application to communicate with printing devices. Print drivers are composed of three fi les that act together as a printing unit: printer graphics driver, printer interface driver, and characterization data fi le.
Printer Pooling An effi cient way to streamline the printing process. One software interface can send print jobs to a pool of printing devices, of which only one printing device actually prints the document.
Printing Software Software that manages a specifi c printing device (or devices, in case of printer pooling). The printer determines how the print job gets to the printing device.via parallel serial, USB port, or the network.
Print Job Source code consisting of both data and commands for print processing.
All print jobs are classifi ed into data types. The data type tells the spooler what modifi cations need to be made to the print job so it can print correctly on the printing device.
Print Monitor Controls access to the printing device, monitors the status of the device, and communicates with the spooler, which relays this information via the user interface. Controls the data going to a printer port by opening, closing, confi guring, writing, reading, and releasing the port.
Print Processor Completes the rendering process. See also rendering.
Print Queue The line that handles printing requests and supplies fi les to the printing device in their proper order.
Print Router Routes the print job from the spooler to the appropriate print processor.
Print Server Controls network printing and services printing requests. Print servers can be hardware devices or a software solution.
Print Spooler A service that intercepts print jobs to the printer and redirects them to disk or memory until the print device is ready for them.
Process A program that has its own set of resources.
Process Manager Responsible for process and thread objects, including deleting, creating, and managing these objects. A process is a program, or a part of a program, that has an address space, contains objects, and spawns threads that need to be processed.
Properties A characteristic of an object. For example, a user object has a City property which describes the city that the user is from.
Protocol A set of rules governing formatting and interaction that enables machines to communicate across a network. Windows supports several protocols, including TCP/IP, IPX /SPX, and DLC.
Protocol Stacks Protocols are grouped together to form protocol stacks, which are capable of doing everything from receiving data from an application to putting the data onto the network medium.
Proxy Server A local server between the client workstation and the Internet.
A proxy server provides security, remedies the need for each workstation to have a direct connection to the Internet, and enables several computers to use a single
Internet connection.
PSTN See Public Switched Telephone Network.
Public Folders Used by the Exchange Server to facilitate collaborative workfl ow processes.
Public-Key Cryptography Consists of a public key and a private key. The public key is given freely to anyone who needs it, and the private key is kept secret by the key.s owner and is stored in the user.s security fi le.
Public Switched Telephone Network (PSTN) The technical name for the medium you use every day to make phone calls and send faxes. The Remote
Access Service enables connections across several media. The most common of these is PSTN.
Public Wireless Networks Public data networks operated by third parties that receive a monthly fee from users in exchange for providing wireless data service.
Pull Feed A newsfeed that occurs when the local host initiates the communication to start the replication of messages.
Pull Partner All WINS replication is a pull activity. A pull partner is a WINS server confi gured to make a request for database updates at a given time interval to other WINS servers.
Push Feed A newsfeed that occurs when the service provider confi gures its servers to send news messages to your server.
Push Partner A WINS Service that sends update notifi cation messages to its partner when its WINS database has changed.
Quarter Inch Cartridge (QIC) A tape cartridge format common for backup tapes.
RAID See Redundant Array of Inexpensive Disks.
Random Access Memory (RAM) Short-term storage memory, physically residing in the computer on memory chips. Because computer applications use RAM in their processing, the amount of RAM in a computer is a major determinant of how well the computer works.
RARP See Reverse Address Resolution Protocol.
Real-Time Scanning An option on virus-protection software that scans every fi le that is accessed, opened, saved, or downloaded.
Redirector Also called a requester, a redirector is software that accepts I /O requests for fi les and then sends the request to a network service on another computer.
Reduced Instruction Set Computing (RISC) Enables fast, effi cient processing of a small number of instructions. Processors such as DEC Alpha, MIPS, CISC, and
PowerPC are all based on the RISC design.
Redundant Array of Inexpensive Disks (RAID) Minimizes the loss of data when problems occur in accessing data on a hard disk. RAID is a fault-tolerant disk confi guration in which part of the physical storage contains redundant information about data stored on the disks. Standardized strategies of fault tolerance are categorized in RAID levels 0 through 5. Each level offers various mixes of performance, reliability, and cost. The redundant information enables regeneration of data if a disk or sector on a disk fails or if access to a disk fails. RAID 0 has no redundant information and therefore provides no fault tolerance. RAID 5 is also known as disk striping with parity.
Registry A central database of all software and hardware settings on a Windows system.
Registry Editor A Microsoft tool (REGEDIT.EXE or REGEDT32.EXE) to view and modify the Registry.
Remote Access Service (RAS) The dial-up service running on a server that enables users to access the network remotely by telephone lines.
Remote Procedure Call (RPC) An IPC mechanism used by programmers to create an application consisting of multiple procedures; some run on the local computer, and others run on remote computers over a network. Also, a request sent to a computer on the network by a program, requesting the computer to perform a task.
Rendering The process of translating print data into a form that a printing device can read.
Repeater Connects network cables by regenerating signals so they can travel additional distances.
Request for Comment (RFC) Documents that publish the standards for
TCP/IP.
Reservation An IP address that is reserved for a specifi c DHCP client.
Resource Domains A domain in the master domain model (multiple master domain and the complete trust models) that has control of its own resources. The master domain controls account information, and resource domains control resources, such as printers and fi les, within their domain. Resource domains were popular in the Windows NT environment.
Reverse Address Resolution Protocol (RARP) Enables a machine to learn its own IP address by broadcasting to resolve its own MAC address.
RFC See Request for Comment.
RG-58 See Thinnet.
Ring Topology A network topology that connects the computers in a circular fashion. If one computer fails, the entire network fails, so this topology is rarely used.
Terminators are not necessary in a ring topology. Signals travel in one direction on a ring while they are passed from one computer to the next. Each computer checks the packet for its destination and passes it on as a repeater would. If one of the computers fails, the entire ring network goes down. See also Bus Topology and Star
Topology.
RISC See Reduced Instruction Set Computing.
RJ-45 The RJ-45 connector is used with twisted-pair cables. It looks like a telephone connector but is wider. There are eight pins, hence there are eight wires.
Ethernet implementations can use either four or all eight wires. If only four wires are used, the pins you should know are 1, 2, 3, and 6. An RJ-45 patch cable can be plugged directly into the back of a twisted-pair network adapter, or less commonly, it can be attached to an external transceiver. The patch cable usually runs to a wall receptacle, which is wired back to a patch panel and ultimately back to a wiring hub.
Roaming Profi le The roaming profi le enables you to keep your user preferences in one location so that any changes you make to the profi le are used on any computer that you log on to. Gives users the same desktop environment on any workstation they log on to.
Roaming User A user who logs on to the network at different times from different computers.
Root (1) The top level of a directory structure, above which no references can be made. (2) The administrative account found in UNIX /Linux.
ROUTE Command that can be used to add, modify, delete, and display route information for one or all interfaces. Used to confi gure network routing tables.
Router A device that connects more than one physical network, or segments of a network. As packets reach the router, the router reads them and forwards them to their destination, or to another router.
Routing The process of forwarding a packet from one segment to another segment until it arrives at its fi nal destination. A router makes decisions as to where to send network packets by looking at the network addresses of the packets it receives before passing them on.
Routing Table The list of available routes known by the router. Used by routers to determine whether data are destined for the local network or not.
RPC See Remote Procedure Call.
RS-232C Null Modem Cable Null modem cables, or LapLink cables, can be used to connect the RAS server serial port directly to the serial port of the client machine.
SAM See Security Access Manager; Security Accounts Manager.
SAPI See Service Address Point Identifi er.
Satellite A communication satellite functions as an overhead wireless repeater station that provides a microwave communications link between two geographically remote sites.
Scaleable The capacity to change with the network. As requirements change, a scaleable network can grow or shrink to fi t the requirements.
Script Used to describe programs, usually those written in an interpreted language, as opposed to a compiled language.
SCSI See Small Computer System Interface.
Secret-Key Cryptography Encrypts and decrypts messages using a single secret key called a bulk encryption key in the Key Management Server. Two examples of secret key cryptography are DES and CAST. The Key Management Server supports
CAST 40 and CAST 64. DES and CAST 64 are available only in North America.
Security Access Manager (SAM) Database A database that maintains all user, group, and workstation accounts in a secure database along with their passwords and other attributes.
Security Accounts Manager (SAM) A set of routines responsible for managing the directory service database.
Security Descriptors Describe the security attributes for an object and have the following parts: Owner security ID (identifi es the owner of the object, which enables that person to change the permissions for the object); Security ID of the primary group (only used by the POSIX subsystem); Discretionary access control list (identifi es the groups and users who are allowed and denied access); and the System access control list (specifi es which events get logged into the security log fi le.)
Security ID (SID) Uniquely identifi es each user, workstation, and server on the network.
Security Reference Monitor Component of the Windows operating system that is responsible for checking access on objects, manipulating rights, and generating audit messages.
Segment A portion of the network that carries network broadcasts.
Serial Line Internet Protocol (SLIP) A TCP/IP protocol that provides the capability to transmit IP packets over a serial link, such as a dial-up connection over a phone line.
Server A computer that provides shared resources to network users.
Server Alert Used to send notifi cation messages to users or computers. Server alerts are generated by the system and relate to server and resource use. They warn about security and access problems, user session problems, printer problems, and server shutdown because of power loss when the UPS service is available.
Server Manager A utility not only for managing servers but also for managing workstations and the domain.
Server Message Block (SMB) File sharing protocol in Windows.
Server Mirroring Duplicating a complete server to reduce the demand on the main server.
Service Address Point Identifi er (SAPI) Identifi es the particular interface on the switch that devices are connected to.
Service Pack A program that provides new functionality, adds more capability, or corrects a bug in an earlier release. Service packs provide software updates in between full releases of the program.
Service Profi le Identifi er (SPID) An alphanumeric string that identifi es the
ISDN terminal capabilities by pointing to a memory location that stores details about the device.
Services A service is a discrete unit of functionality provided by the Windows operating system.
Session Layer Layer 4 of the OSI model that manages dialogs and sessions between computers.
Sessions A session is a reliable dialog between two computers. Because connection-oriented services can provide reliable communication, they are used when two computers need to communicate in a session. Sessions are maintained until the two computers decide that they are fi nished communicating. A session is just like a telephone call. You set up a telephone call by dialing (handshaking), you speak to the other person (exchange data), say .Goodbye,. and hang up when fi nished.
SFC See System File Checker.
Share A setting to make resources such as printers, CD-ROM drives, and directories available to users on the network.
Shared Processing When the processing for a task is done not only on the client, or only the server, but on a combination of both the client and the server.
Share-Level Security Used to give other users access to your hard disk via the network. The four types of share permissions are No Access, Read, Change, and Full
Control.
Shell A program that provides communication between a server and a client or a user and an operating system.
Shielded Twisted Pair (STP) A twisted-pair cable that has foil wrap shielding between the conducting strands and the outer insulation.
SID See Security ID.
Simple Mail Transfer Protocol (SMTP) Protocol used to send mail over the
Internet.
Simple Mail Transfer Protocol Service Extensions (ESMTP) ESMTP is an extension to the SMTP protocol. Systems that support ESMTP support a richer command set.
Simple Network Management Protocol (SNMP) An Internet standard for monitoring and confi guring network devices. An SNMP network is composed of management systems and agents.
Simplex Dialogs Used by the OSI session layer to enable data to fl ow in only one direction.
Single Instance Storage A message is sent to more than one recipient on a server, and the message is stored only once on the server. The Exchange Server.s
Information Store uses single instance storage.
SLIP See Serial Line Internet Protocol.
Small Computer System Interface (SCSI) A high-speed interface used to connect peripherals such as hard disks, scanners, tape drives, and CD-ROM drives. SCSI enables up to seven devices to be connected in a single chain. See also
Integrated Drive Electronics (IDE).
SMB See Server Message Block.
SMDS See Switched Megabit Data Service.
SNA See Systems Network Architecture.
Sniffer Network monitoring tool that analyzes the traffi c on the network and can help solve problems that are infrastructure related.
SNMP See Simple Network Management Protocol.
SONET See Synchronous Optical Network.
SPID See Service Profi le Identifi er.
Star Bus Topology If you replace the computers in a bus topology with the hubs from star topology networks, you get a star bus topology.
Star Ring Topology Also called star wired ring, the smaller hubs are internally wired like a ring and connected to the main hub in a star topology.
Star Topology All computers are directly cabled to a hub. See also Bus Topology and Ring Topology. One advantage of a star topology is the centralization of cabling.
Stateless The most effi cient type of network communication, a protocol that needs no information about communications between sender and receiver.
Static Entries Entries that are manually added. This could apply to statically confi gured routers in which the routing table is updated manually by the network administrator or the ARP cache can be manually updated.
Static Routing Confi guration method used by early routers. It required programming exactly which networks could be routed between which interfaces, especially if there were many network interfaces.
STP See Shielded Twisted Pair.
Stripe Sets Without Parity Like volume sets, except that they provide performance gains. They can combine 2 to 32 areas of free space as a single volume.
However, the free space must be on different hard disks, and each hard disk must contain the same amount of free space that you want to use for the size of the stripe set.
Striping Data RAID 5 uses a method of striping data across several hard disks, with parity information also included. This parity information is striped across the drives, rather than being stored on a single hard disk.
Subnet Mask Determines which bits in the IP address apply to the network ID and which bits are part of the host ID.
Subnetting The breaking up of the IP address range into multiple IP address ranges.
Swap File See Paging File.
Switch A network device that is similar to a hub but only forwards the data to the port on the switch that the destination address is connected to. Switches are used instead of hubs to increase performance on the network.
Switched Megabit Data Service (SMDS) SMDS technology transports data in 53-byte calls at data rates of 1.544 to 45 Mbps.
Symmetric Cryptography Both the sender and receiver use a single key.
Symmetric Multiprocessing (SMP) A multiprocessor operating system in which there is no master processor in that all threads, including system threads can be scheduled to run on any processor.
Synchronous Communication Sends all data in a steady stream and uses a clock signal to interpret the beginning and end of a packet.
Synchronous Optical Network (SONET) A fi ber-optic network communications link. SONET supports rates as high as 13.22 Gbps.
System Administrator Manages the network. It is this person.s responsibility to ensure that network functions are running smoothly.for example, that backups are complete, network traffi c is running smoothly, and drive space is available when needed.
System File Checker (SFC) Windows tool for automatically checking that all system fi les are in order and that none are corrupt.
System Partition In Windows, where the hardware specifi c fi les needed to boot are located. The active partition is the system partition on Intel-based computers.
Systems Network Architecture (SNA) The basic protocol suite for IBM.s
AS/400 and mainframe computers.
T1 A widely used digital transmission link that uses a point-to-point transmission technology with two-wire pairs. One pair is used to send and one to receive. T1 can transmit digital, voice, data, and video signals at 1.544 Mbps.
T3 Similar to T1 but designed for transporting large amounts of data at high speeds. T3 is a leased line that can transmit data at 45 Mbps.
TA See Terminal Adapter.
Task Manager Tool for observing and deleting processes; also provides a more granular level of detail when looking at processes and threads, including the option of removing or setting the priority of individual processes.
T-Connector A T-shaped device used in Thin Ethernet cabling to connect the thinnet cable to the NIC.
TCP/IP See Transmission Control Protocol /Internet Protocol.
TDR See Time Domain Refl ectometer.
TE See Terminal Equipment.
TechNet A technical support CD-ROM published by Microsoft. TechNet is a searchable database of all of Microsoft.s articles and documentation on nearly all
Microsoft products.
Telephony Advanced Programming Interface (TAPI) TAPI enables communication applications on a computer to control functions of the telephone and manages all signaling between the computer and a telephone network.
Telnet A terminal emulation program used to remotely connect to an application or server.
Template A template is a partially completed object, designed to help you start a task. Windows Server provides templates to help the new administrator confi gure objects and complete other tasks.
Terminal Adapter (TA) Connects TE2 devices to an ISDN network. TA connects through the R interface to the TE2 device and through the S interface to the ISDN network.
Terminal Endpoint Identifi er (TEI) Identifi es the particular ISDN device to the switch. This identifi er changes each time a device is connected to the ISDN network.
Terminal Equipment 1 (TE1) Any device that can connect directly to ISDN.
Terminal Equipment 2 (TE2) Any non-ISDN ready device that requires a terminal adapter to work with ISDN.
Terminator To prevent packets from bouncing up and down the cable, devices called terminators must be attached to both ends of the cable. A terminator absorbs an electronic signal and clears the cable so that other computers can send packets on the network. If there is no termination, the entire network fails.
TFTP See Trivial File Transfer Protocol.
Thick Ethernet See 10Base5.
Thicknet See 10Base5.
Thickwire Coaxial Cable See 10Base5.
Thin Ethernet See 10Base2.
Thinnet See 10Base2.
Thinwire Coaxial Cable See 10Base2.
Thrashing Occurs when information is being swapped in and out of memory, to and from the paging fi le, at a tremendous rate. It.s caused by a defi ciency of RAM.
Thread The smallest unit of code in a process.
Throughput A measure of the rate at which data are transferred across a network, expressed in bits per second (bps).
Thunking Process used by Windows to translate 16-bit calls into 32-bit calls and vice versa.
Time Domain Refl ectometer (TDR) A device that sends an electronic pulse down the network cable. The pulse is refl ected when it reaches a fl aw or the end of the cable.
Timeout Interval Timeout intervals are used to interpret the time to travel between hops. A normal LAN usually lists devices as being less than 10 milliseconds away. By default, 2 seconds is the timeout before a .reply timed out. message is generated. You can use the -w option to raise this value for troubleshooting.
Timeout Value The timeout value determines the amount of time in milliseconds the program will wait for a response before moving on. Using this option will enable you to understand a little more about the problem that is occurring. For example, if you notice that many responses are timing out, you can raise this value. If after raising this value, remote devices are responding, this could be a good indication that you have a bandwidth problem.
Token An electronic marker packet, used in ArcNet and FDDI networks, that indicates which workstation is able to send data on a Token Ring topology.
Token Ring A networking topology that is confi gured in a circular pattern and circulates an electronic token on the ring to pass data. A Token Ring network has great reliability, but it is costly compared to other network architectures.
Tone Generator Used to perform tests on phone and network lines by clipping to a wire, terminal panel, or standard modular jack. Aids in the identifi cation of wires during the wire-tracing process.
Topology The physical layout of a network. Common topologies include bus, ring, and star.
Tracert Utility commonly used to locate failures along a TCP/IP communications path by tracing the route from origin to destination. Each router interface encountered is echoed to the screen along with some statistical information about the path timing.
Transceiver The portion of the network interface that actually transmits and receives electrical signals across the transmission media. It is also the part of the interface that actually connects to the media. See also External Transceiver;
Onboard Transceiver.
Transceiver Type The transceiver type setting is required for network adapters that are capable of attaching to more than one media type. Typical cards of this nature include Ethernet cards that have both twisted-pair and coaxial connectors.
One of the more common oversights in confi guring a NIC, this setting renders the card nonfunctional if confi gured for the wrong media connection. To alleviate this problem, some cards of this type have an auto setting that causes the card to search for the transceiver that has media connected to it.
Transmission Control Protocol/Internet Protocol (TCP/IP) Transmission
Control Protocol /Internet Protocol (TCP/IP) is the most common protocol used today. A routable protocol, TCP/IP is the protocol on which the Internet is built.
TCP/IP is very robust and is commonly associated with UNIX systems. TCP/IP was originally designed in the 1970s to be used by the Defense Advanced Research
Projects Agency (DARPA) and the U.S. Department of Defense (DOD) to connect systems across the country. This design required the capability to cope with unstable network conditions. Therefore, the design of TCP/IP included the capability to reroute packets.
Transport Layer (1) The OSI layer that ensures reliable delivery of data to its destination. The transport layer consists of two protocols: the transmission control protocol (TCP) and the user datagram protocol (UDP). (2) TCP/IP layer that is located at layer 3 of the TCP/IP model. The main responsibility of the Transport layer is to provide communication from one application to another application.
Tree A hierarchy of domains in Active Directory that share the same DNS namespace.
Trivial File Transfer Protocol (TFTP) Similar to the fi le transfer protocol, but does not require user authentication.
Trunk The cable used in a bus topology is called a trunk, a backbone, or a segment.
Trusted Domain The domain that contains the directory service database, thereby containing the user accounts. A user logging in to one domain can be authenticated by another domain if a trust relationship was previously established.
Trust Relationship A connection between two domains. Once a trust is established, users from one domain can be given permission to access resources on another domain.
Tunneling When a PPP session is established, PPTP creates a control connection between the client and the remote PPTP server.
Twisted-Pair Cable A cable type in which conductive wires are twisted to help reduce interference. There are two types of twisted pair: shielded and unshielded. See also Coaxial Cable and Fiber-Optic Cable.
UART See Universal Asynchronous Receiver/Transmitter.
UDP See User Datagram Protocol.
Unattended Backup The backup program launches at a scheduled time, does the specifi ed backup, then terminates.
UNC See Universal Naming Convention.
Uniform Resource Locator (URL) Provides the address to a document on the
World Wide Web.
Unimodem With Windows 95/98/ME, an additional subsystem called unimodem is available to simplify dial-up networking. Unimodem provides an easy, centralized mechanism for installing and confi guring modems.
Uninterruptible Power Supply (UPS) A battery backup system commonly used on fi le servers to protect in times of power outages.
Universal Asynchronous Receiver/Transmitter (UART) The hardware pieces designed for the computer to send information to a serial device.
Universal Naming Convention (UNC) A standardized way of connect to a shared resource on a computer. The syntax is always \computername\sharename.
Universal Serial Bus (USB) An external bus standard that enables devices to be added and automatically installed and confi gured without the need for user intervention or rebooting. USB enables up to 127 simultaneous connections, with connection speeds between 12 and 400 Mbps.
UNIX UNIX is a powerful multitasking operating system that can run many processes in the background while enabling users to work in the foreground on an application. The multiuser feature enables many users to use the same machine. The last feature, networking capability, is becoming standard in operating systems developed since 1995. UNIX has been the leader in several powerful and diverse utilities that have ported over to other operating systems.
Unshielded Twisted Pair (UTP) A twisted-pair cable that does not have any shielding between the conducting strands and the outer insulation.
UPS See Uninterruptible Power Supply.
URL See Uniform Resource Locator.
USB See Universal Serial Bus.
User Any person who accesses the network.
User Account Represents a user who accesses the resources on a computer or network. User accounts do not have to represent individuals; they can also be accounts for services, such as a QL Server account.
User Datagram Protocol (UDP) UDP offers a connectionless datagram service that is an unreliable .best effort. delivery. UDP does not guarantee the arrival of datagrams, nor does it promise that the delivered packets will be in the correct sequence. Applications that don.t require an acknowledgment of data receipt use UDP.
User Environment Profi le Enables you to control the system environment according to which user is logged on.
User Mode Also called nonprivileged processor mode. This is where applications and the various subsystems are run. User Mode is designed to prevent applications from bringing down the operating system.
Username A name used by a user to log on to a computer system.
User Profi le Stores user preferences, such as screen savers and last documents used, and environmental settings, such as program groups and network connections.
The user profi le is the set of stored characteristics that set the default desktop confi guration for each individual user account. See also Roaming and Local.
User Right Enables the user to perform specifi c operations on the computer. You set user rights to control which operations a user or group performs. Some vendors may use the term .system privileges..
UTP See Unshielded Twisted Pair.
Vampire Tap Thickwire uses a connection method that typically involves an external transceiver connected to the adapter.s AUI port. This external transceiver has a connection called a vampire tap. The vampire tap consists of a pin that is inserted into the hole drilled in the cable and a clamp that holds the tap onto the cable. One of the challenges of this type of connection is to position the tap so that it contacts the center conductor without shorting to the shield surrounding it. These diffi culties, as well as the cost and size of thickwire cable, have rendered it largely obsolete, although it can occasionally be found in existing installations.
Verify Operation Used to compare fi les on the hard disk to fi les that have been backed up to tape.
Virtual Circuit Virtual circuits establish formal communication between two computers on an internetwork using a well-defi ned path. This enables two computers to act as though there were a dedicated circuit between the two, even though in fact there is not. The path the data takes while being exchanged between the two computers might vary, but the computers do not know this; they do not need to. Since the virtual circuit uses connection-oriented communication, all the points that comprise the circuit ensure that the data gets through unharmed, even if those points change while the virtual circuit is in place.
Virtual File Allocation Table (VFAT) Enables the use of long fi lenames, while maintaining the 8.3 naming convention for older applications viewing the same fi le.
Released with the Windows 95 operating system.
Virtual Local Area Network (VLAN) A Virtual Local Area Network creates a small grouping of PCs that are required to communicate with one another only on a larger network. This is accomplished by specifying the ports on the switch that the
PCs are connected to. The switches limit the VLAN members to communicating only with other PCs within the same VLAN.
Virtual Memory Created by Windows to simulate RAM on a computer when more memory is needed. It does this by using the computer.s hard disk as needed.
Virtual Memory Manager (VMM) Responsible for the use of virtual memory and the paging fi le in the system.
Virtual Private Network (VPN) Provides tunneling through a public network with a secure communications channel. VPNs use PPTP or other protocols for secure connections to a remote network. By using PPTP or a similar tunneling protocol you are able to tunnel through an Internet or LAN connection without compromising security.
Virus Signature File A database of known viruses that the antivirus software uses when scanning fi les to eliminate viruses. The virus signature fi le must be kept current.
VLAN See Virtual Local Area Network.
VMM See Virtual Memory Manager.
Volume A logical division of space on a physical drive that is treated as a single unit. A volume is a part of a hard disk used to store information.
Volume Sets The combining of different-sized areas of free space as a single volume (drive letter) from any type of hard disk (IDE, SCSI, or ESDI). Volume sets don.t provide any fault tolerance or performance gains. They are simply used to combine multiple areas of free space as one single volume.
VPN See Virtual Private Network.
WAP See Wireless Access Point.
Well-Known Ports See Port Numbers.
Wide Area Network (WAN) Multiple local area networks (LANs) linked over a broad physical distance, ranging from a few miles to across the world. TCP/IP is the primary WAN protocol and was developed to provide reliable, secure data transmissions over long distances.
Win32 The primary subsystem for Windows, it is responsible for all user input and output. The Win32 subsystem is also responsible for receiving requests from the other environment subsystems.
Windows Internet Naming Service (WINS) The Windows Service that provides a map between NetBIOS computer names and IP addresses. This permits
Windows networks to use either computer names or IP addresses to request access to network resources.
Windows Scripting Host Windows technology that enables an administrator to use more robust, language-independent commands in logon scripts through ActiveX scripting.
Windows Update Web site to which you can connect to view available updates for your system. You may install the updates from the system as well.
WINIPCFG The Windows 9x-based graphical utility used to display the current
TCP/IP confi gurations on the local workstations and to modify the DHCP addresses assigned to each interface. See also IPCONFIG.
WINS See Windows Internet Naming System.
Wireless Access Point (WAP) A network device that allows wireless clients to connect to the wireless network. Wireless clients connect to the access point and send data to other hosts on the network through the access point.
Wireless Bridge Provides wireless connectivity of remote Ethernet networks and is fully transparent to network protocols and applications.
Wireless Connectivity Connectivity is achieved without cable connections.
Wireless Networking A network confi gured to use communication techniques such as infrared, cellular, or microwave, so that cable connections are not required.
Wireless Topology A wireless topology is one in which few cables are used to connect systems. The network is made up of transmitters that broadcast the packets using radio frequencies. See Cells.
Workgroup A group of computers that are each individually managed.
Workstation The client machine used to access a network.
Write Once, Read Many (WORM) An optical storage medium that permits you to write to it only once but to read from it many times. CD-ROM drives are
WORM devices.
X.25 A protocol that runs on a worldwide network of packet-forwarding nodes that deliver X.25 packets to their designated X.121 addresses. X.25 networks transmit data with a packet-switching protocol, bypassing noisy telephone lines.