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This page contains answers to common questions handled by our support staff, along with some tips and tricks that we have found useful and presented here as questions. All of the following are suggestions and the user makes the final decision whether to implement them or not. Always make a backup of your computer before attempting any changes. If you have any doubts about making changes, wait and talk to someone experienced with your type of changes.
Note: In these answers we will follow a few shorthand conventions for describing user-interface procedures. Key combinations will be presented like this: Ctrl+Alt+Delete, which means that you should press and hold down the Control key, the Alt key, and the Delete key at the same time. Menu selections will be presented like this: File->Open, which means that you should open the File menu, and then make the Open selection.
| 10Base-2 | The type of coaxial cable most often used for Ethernet Networks. Also known as thinnet or cheapernet. The maximum length of a single segment is 185 meters (600 feet). |
| 10Base-5 | The original Ethernet coaxial cable, now used mostly as the backbone for larger networks. Also know as yellow cable or thick cable. The maximum length of a single segment is 500 meters (1640 feet). |
| 10Base-T | An Ethernet network that uses twisted pair (also known as RJ-45) cabling between a network interface card and a hub to connect the network together. This runs at a speed of 10 Mbps. The maximum length of a single length segment is 100 meters (330 feet). |
| 100Base-FX | The Ethernet standard for high-speed fiber-optic connections. |
| 100Base-T | The Ethernet networking standard that supports a data transmission rate of 100Mbps and is backward compatible to 10Base-T networks. 100Base-T is based on the IEEE 802.3u standard and is commonly referred to as Fast Ethernet. |
| 100Base-T4 | An alternative standard for 100Mbps Ethernet using four-pair Category-3 cable. |
| 100Base-TX | An Ethernet network that uses twisted pair (also known as RJ-45) cabling between a network interface card and a hub to connect the network together. This runs at a speed of 100 Mbps. It uses two-pair Category-5 twisted pair cable. |
| 100VG AnyLan | A standard for 100Mbps Ethernet that isn't as popular as 100Base-T. It uses twisted pair cable just like 100Base-T and 100VG AnyLan. |
| 1000Base-T | A new standard for 1000Mbps Ethernet using four-pair Category-5 unshielded twisted pair cable. 1000Base-T is also known as Gigabit Ethernet. |
| 2B1Q | Two Binary One Quaternary. A line coding technique used in traditional telecommunications offerings including ISDN. The 2B1Q line coding is used for some DSL, including SDSL, HDSL and IDSL. |
| 2B+D | Refers to Basic Rate Interface (BRD) configuration of ISDN; two B(earer) channels of 64Kbps each, plus one D(elta) channel of 16Kbps. |
| 32-Bit | Components or applications that work with data 32 bits at a time. A 32 bit operating system such as OS/2 Warp, Windows 95, Windows NT, Windows 2000, Windows 98, Windows ME, or Windows XP works with information in 32 bit groups. |
| 404 Error | The page that loads when you type in a URL that doesn't exist, denoting that the web page or object you are looking for isn't available under that name. |
| 802.2 | The forgotten IEEE standard. The more glamorous 802.3 standard relies upon 802.2. |
| 802.3 | The IEEE standard known as Ethernet. |
| 802.11g | Upcoming wireless networking specification designed to be compatible with 802.11b and 802.11a technologies, with transmission speeds from 25Mbps to 54Mbps. |
| 16550 | UART (serial port) chip that supports speeds up to 115200bps (115.2Kbps). |
| 16650 | UART (serial port) chip that supports speeds up to 230400bps (230.4Kbps) a good choice for external ISDN TAs. |
| 16750 | UART (serial port) chip that supports speeds up to 460800bps (460.8Kbps) also a good choice for external ISDN TAs. |
| AAUI | Apple Attachment Unit Interface. A type of connector used in some Apple Ethernet netwroks. |
| AC | Alternating Current. An electrical current that regularly and systematically reverses, or alternates, its direction of travel. The direction in which an electrical current flows is referred to as its polarity. One cycle or hertz is complete when the current has made two complete changes of polarity; in other words, the current has traveled both directions. |
| Access Point | The network hub device for a wireless network. |
| Access Rights | A list of rights that tell you what you can and can't do with network files and directories. |
| Account | You need an account to access a network. The network knows who you are and what rights you have on the network by your account. |
| ACPI | Advanced Configuration and Power Interface. An industry specification for the efficient handling of power usage by both desktop and mobile PC's. ACPI specifies how a computer's BIOS, operating system, and attached peripherals communicate with each other about power usage. ACPI can allow for a variety of power-saving features to activate when required. For example, the user can specify at what time a device, such as a display monitor is to turn off or on, or the operating system can lower the CPU clock speed during times when applications don't require the full processor clock speed. In order for the ACPI to work on your computer, your BIOS must include the ACPI software, and the operating system must be ACPI compatible. ACPI is designed to work with Windows 98, Windows 2000, and windows XP (both Home and Professional). |
| Active Directory | The directory service in Windows 2000. |
| Active Server Pages | An Internet feature from Microsoft that enables you to create Web pages with scripts that run on the server rather than on the client. Also known as "ASP". The latest version is called ASP.NET. |
| Activity | A light on some broadband modems used to display data transfer taking place. |
| Acronym | An abbreviation made up of the first letters of a series of words. |
| Adapter Card | An electronic card you can plug into one of the adapter slots in all computers. This will give it some new capabilities such as displaying millions of colors, talking to other computers over the phone lines or cable or accessing a network. |
| Add-Ons | Also known as plug-ins, these are small applications that enhance the capabilities of your existing browser or provide it with new functions. These programs attach to your browser but don't become part of it. |
| Address Book | A list of users you regularly communicate with thru your e-mail system. |
| Address Book Provider | A MAPI address book provider provides access to any existing central database that holds information on all users and recipients in a messaging system. The Exchange directory is an example of an address book provider. |
| Address List | A collection of recipients in the address book, organized by their recipients container. Also see Personal Address Book, Global Address List. |
| Address Space | A set of address information associated with a connector or gateway that identifies a certain type or group of recipients and the route that messages to those recipients should take. The address space exists so Exchange MTA can determine how to get a message to its final destination. Also see Connector. |
| Administrator | The person responsible for setting up the network and keeping it running. Also known as the Network Manager. |
| Administrator Program | A graphical user interface (GUI) that administrators use to manage and configure Microsoft Exchange Server objects such as sites, servers and organizations. |
| ADSL | Asymmetric Digital Subscriber Line. DSL that supports high speed data communications speeds of up to 8Mbps downstream and up to 640Kbps upstream. ADSL can deliver simultaneous high speed data POTS voice service over the same telephone line. ADSL is the most widely deployed by ILECs. |
| ADSL Forum | This industry organization is made up of computer and telecommunication companies that define DSL standards for submission to standards bodies. This group is responsible for accelerating ADSL technologies, products and services as well as promoting the technology. |
| ADSL Lite | Nickname for G.lite. A DSL based on the new G.lite standard that supports 1.5 Mbps downstream and 348 Kbps upstream. |
| Advanced Security | This gives administrators and users the ability to protect and verify messages. |
| AFP | Apple Filing Protocol. A protocol used by Apple Computers. |
| AFT | Adapter Fault Tolerance |
| AGP | Accelerated Graphics Port. This is an interface specification that enables 3D graphics to display quickly on PC's. The main area that AGP has benefited is the gaming industry, allowing creation of gaming environments that are more realistic and contain real world elements such as clouds, smoke and fog. |
| ALB | Adaptive Load Balancing |
| Algorithm | A list of instructions that can be used to accomplish a task. |
| Alias | Typically, a shorthand version of the mailbox owner's name, its used to address messages. This item is specified in the Recipient property page. |
| Allocation Unit | Windows allocates space to files one allocation unit at a time. The allocation unit is typically 2.048KB to 4.096KB, depending on the size of the disk. Also known as a cluster. Netware and Windows NT/2000 can use allocation schemes that are more efficient than standard Windows. |
| Always On | Refers to a DSL or cable connection as a dedicated connection. There is no dial-up process to connect to the Internet because the computer is linked directly to the Internet. |
| Analog | The opposite of digital. Telephone data is analog because it uses high and low tones. |
| Analog Modem | Converts digital computer signals to analog telephone signals and back. It is the common type of modem supplied with most computers; also called a dial-up modem. |
| ANSI | American National Standards Institute. This is a nongovernmental organization that develops and publishes standards for voluntary use in the United States. |
| Antivirus Program | A program that searches for viruses on your computer or network and if found allows you to delete or quarantine them or possibly do nothing but warn you. |
| AOL | America on Line. The largest ISP and online service in the U.S. |
| Apache | The most popular Web Server on the Internet. It comes free with most versions of the Linux operating system. |
| API | Application Programming Interface |
| APPC | Advanced Program-to-Program Protocol |
| Apple Talk | Apple's networking system for Macintoshes. |
| Applet | A small application or utility that performs useful tasks, but is designed for use within larger programs. |
| Application | A self contained software program that performs a set of clearly defined tasks controlled by the user. |
| Application Layer | The highest layer of the OSI reference model, which governs how software communicates with the network. |
| Archive Bit | A flag that is kept for each file to indicate whether the file has been modified since it was last backed up. |
| ARCnet | A slow but steady network topology developed originally by Datapoint. ARCnet uses a token passing scheme similar to Token Ring. |
| Areal Density | The number of bits of data that can be recorded onto the surface of a disk or platter usually measured in square inches. |
| ARM | Automatic Reliability Monitoring |
| ARP | Address Resolution Protocol |
| ARPAnet | The ancestor of the internet. It was developed by the U.S. Department of Defense to allow communication in case of nuclear attack. |
| ASCII | American Code for Information Interchange. A 7-bit code standard for representation of characters, numbers, symbols and control characters, for use in data communication and data storage. |
| Asymmetric-Key Encryption | Encrypting a file using a widely known key called a public key. A private key, known only to the recipient, is used to decrypt the file. |
| Asymmetrical | Refers to upload speeds for Internet services running slower than download speeds. |
| AT/ATA | Name of standard interface and protocol for hard drives. See also IDE. Advanced Technology Attachment is generally used as a synonym for EIDE, as is UltraATA. |
| ATA | AT Attachment |
| ATAPI | AT Attachment Packet Interface (Enhanced IDE) |
| AT Command Set | In communications, a group of instructions that activate certain functions on a modem. Although the AT command set originally was developed for the Hayes modem, it has become the standard for all modems. |
| Athlon | A competitor to Intel's Pentium CPU chip manufactured by AMD. |
| ATM | Asynchronous Transfer Mode. A standard for high speed digital backbone networks. ATM networks are widely used telecommunications and large companies for backbone networks that consolidate data traffic from multiple feeders, such as DSL lines, and different types of media including voice, video and data. |
| Attachment | A file, including an application, graphic element, image or sound, that accompanies an e-mail message. |
| Attributes | Characteristics that are assigned to files. DOS alone provides four: system, hidden, read-only and archive. Network operating systems generally expand the list of file attributes. |
| ATX | An industry wide open specification for a desktop computer's motherboard. ATX improves the motherboard design by taking the small AT motherboard that has been an industry standard and rotating the layout of the microprocessor and expansion slots by 90 degrees. Doing this allows space for more full-length expansion cards and improves cooling. Also specified is a double height space at the rear of the chassis to allow for more possible I/O arrangements for a variety of devices such as LAN connections and USB ports. The new layout is also cheaper to manufacture and uses fewer cables. |
| AUI | Attachment Unit Interface. The large connector found on older network cards and hubs that is used to attach yellow cable via a transceiver. |
| Authentication | Validation of a user's Window NT/2000/2003 server log in information. Also see Trust Relationship. |
| Autoexec.bat | A batch file that DOS executes automatically every time you start your computer. |
| Autoexec.ncf | A batch file that Netware executes automatically every time you load the server software. |
| Autosetup | DirecPC's setup program. It must be run to configure the system initially. If you run it later, it might indicate you are being switched to a new gateway (and maybe a new satellite). |
| AWG | American Wire Gauge. A thickness measurement for copper wiring. The heavier the gauge, the lower the AWG number and the better the quality of the line in terms of supporting a longer distance for a DSL signal. Many local loops use 24 AWG or 26 AWG copper wires. |
| Azimuth | The angle in degrees, measured along the horizon from true (not magnetic) north and the point on the horizon directly below the satellite. It is always measured clock-wise and always is a positive number (0-360). It is one of the settings required to point to a DirecPC satellite dish. |
| Backbone | A trunk cable used to tie sections of a network together. The backbone is often 100Mbps Fast Ethernet. It is usually high speed to handle heavy traffic between local area network segments. |
| BackOffice | A suite of Microsoft programs designed to run on server computers based on Windows NT/2000/2003 Server. |
| Backup | A copy of your important files made for safe keeping in case something happens to the original files. This is something you should do at the end of every day. |
| Backup Copy | A copy of a program or file that is stored separately from the original. If the original files or media are lost, the backup copy may be used for recovery. |
| Bandwidth | The capacity a network or data connection has for carrying data. For analog transmission, bandwidth is the difference between the highest and lowest transmission frequencies possible. It is measured in cycles per second or hetz (Hz). Bandwidth is usually expressed in terms of a digital transmission, and is measured in bits per second (bps). The larger the bandwidth number, the faster the digital transmission. |
| Banias | Low voltage processor designed for ultraportable and thin-and-light notebooks. 2003/1 |
| Banner | A fancy page that is printed between each print job so that you can easily separate jobs from one another. |
| Banner | Can be a portion of a web page, with scrolling or rolling advertising. |
| Batch File | In DOS, a file that contains one or more commands that are executed together as a set. You create the batch file by using a text editor (like DOS Edit command) and run the file by typing its name at the command prompt. |
| Battery Backup | Also referred to as a UPS (uninterruptable power supply), this is a useful accessory for computers and for ISDN connections used for voice phone calls. |
| BBS | (1) Bios Boot Specification (2) Bulletin Board System. Computers accessible to outside users for trading software and communicating through typed messages over their modem. BBSes come in all sizes, from basement dial-in operations run by hobbyists to regional or national systems run by full-time system operators for profit. There are tens of thousands of BBSes in the United States alone. BBSes get their name from the way messages are "posted" for others on the system to read. Users can reply to posted messages or create their own. These conversations are called threads. Most BBSes are designed around particular needs. |
| B-Channel | Bearer channel, one of two 64Kbps channels used for data on an ISDN connection. |
| BCC | Blind Carbon Copy |
| BDC | Backup Domain Controller |
| Benchmark | A repeatable test you use to judge the performance of your network. The best benchmarks are the ones that closely duplicate the type of work you routinely perform on your network. |
| Bender | A reflector used by some fixed-base wireless broadband providers to reflect microwave data to subscribers who don't have a direct line of sight to the transmitter. Benders cannot return traffic, and thus can only be used for one-way communications. |
| BER | Bit Error Rate |
| Best Effort | This is Internet access service that doesn't have a Quality of Service (QoS) guarantee. Most DSL service is a best effort class of service but QoS is emerging as a premium DSL service by some ISPs. |
| BFO | (1) Beat Frequency
Oscillator (2) Blinding Flash of the Obvious [slang] |
| Binary | The name of a number system made up of only two digits, usually 0 and 1. Computers use the binary system extensively to store, receive and transmit data. The number "1" in binary is written as 1. The number "2" is written as 10, where the one is in the "twos" position and a zero is in the "ones" position. The numbers one to 10 in the binary system would be: 1, 10, 11, 100, 101, 110, 111, 1000, 1001, 1010. |
| Bindings | The connection between a network adapter and a network protocol. When you install a network card on a computer running Windows, Windows will bind the installed network protocols to the card so the card can be used on a network. |
| BIOS | Basic Input/Output System (Pronounced bye-0se). A special piece of software built into most computers. BIOS routines control the startup process and other basic functions, such as the keyboard, display and disk drives. On older computers, the BIOS is stored in ROM, which is not erased when the power to the computer is shut off. Newer computers store BIOS on flash ROM, which a user can erase and rewrite if the user needs to update the BIOS. |
| BISDN | Broadband ISDN |
| BISYNC | Binary Synchronous Communications Protocol |
| Bit | Short for binary digit, the smallest unit of computer storage. A bit is a single digit in a binary number, either 1 or 0, often called "on" or "off". |
| Bit Density | Expressed as bits per inch (BPI), the number of bits that can be written onto one inch of track on a disk surface. |
| Bit Map | A type of graphics file in which one or more bits are used to describe the color of each square that makes up the image. Each square represents one pixel. Image resolution is defined by the number of pixels contained within a square inch, commonly referred to as dpi (dots per inch). Lowering resolution can result in individual pixels being viewable; raising resolution can result in files of gargantuan size, with little improvement in quality. One kind of bit-mapped file, with the extension ".BMP", is used extensively in the Windows operating environment / system. |
| Block Sync | A cable modem term used for the signal light indicating that the cable modem is connected properly to the cable network. If this light is blinking, you have lost your connection and must wait until it comes on again. |
| Blog | Short for web log. A blog is an online journal, displayed on a web page. It can be a personal diary, a commentary, a way to broadcast knowledge or information. |
| Blue Screen of Death | What you see when the system really, really crashes. A beautiful blue screen with an error message in white. |
| Bluetooth | A technical industry standard allowing portable devices to interconnect with each other and with home and business devices. With a special chip, PDAs (personal digital assistants), notebook computers, cell phones and other devices can connect with a short-range wireless connection. To install this technology, manufacturers must have their products approved by the Bluetooth Special Interest Group. |
| BMC | Baseboard Management Controller |
| BMP | Bit Map. A type of graphics file in which one or more bits are used to describe the color of each square that makes up the image. The native bit map is the file format Microsoft uses in its OS. BMP supports bit maps with 1, 4, 8, or 24 bits of data per pixel so BMP files can be monochrome, grayscale or full color. Data can be stored in raw format using 4 or 8 bit RLE compression, which is lossless. BMP format is suitable for line drawings and simple color images. One kind of bit-mapped file, with the extension ".BMP", is used extensively in the Windows operating environment / system. |
| BNC T-Connector | This item is a metal connector in the shape of the letter " T ". One end Plugs into the external end of a network card on the back of a computer's case. The other ends form the top of the " T " and connect with network cables. This connector is used with coaxial cable on 10Base-2 networks. |
| BOD | Beginning of Data. Electronic or magnetic sign, a part of the low-level format on tape. BOD signals the start of data. |
| BOM | Beginning of Media. Electronic or magnetic sign, a part of the low-level format on tape. BOM signals the beginning of media. |
| Bonding | (1) Using two or more analog modems (and/or ISDN TAs) to make a single internet connection. The total speed of the connection is the sum of the modem's speeds, but each modem requires its own telephone line. Most ISPs do not support bonding. |
| Bookmark | A saved web site address. When using a bookmark and clicking on the specific web site, the user can quickly return to those pages when necessary without retyping the address again. |
| Boot | To turn on a computer and cause it to start executing the basic startup software, usually housed in the BIOS. Booting up a computer is the first step to using it, as the computer must load certain information in its memory before running more advanced programs. A user might reboot a computer that has crashed in an effort to regain control. |
| Boot Disk | A diskette that contains the necessary part of the operating system so the computer can boot up. Most computers with hard drives boot from that, but older computers might boot from diskettes in the A: or B: drive. It is a good idea to keep a bootable diskette handy in case something goes wrong with the hard drive, as most computers first check the diskette drives for bootable diskettes before checking the hard drive. A faulty hard drive can be bypassed this way. |
| Boot Record | A file system table of the FAT and NTFS file systems, containing information about one partition. (Often refered to as Boot sector, Boot block or Boot Track). |
| Boot Up | This is the process of initializing, testing and configuring a PC during start up. See "Boot" |
| Bottleneck | The slowest link in your network, which causes work to get jammed up. The first step in improving network performance is identifying the bottlenecks. |
| BPI | Bits Per Inch |
| bps | Bits Per Second. A measurement of data transmission speeds. As the name implies, bps is the number of bits that pass a certain point in one second. Some of today's fastest modems transfer information over phone lines at 56Kbps (kilobits per second). |
| BRI | Basic Rate Interface. The lower-cost form of ISDN. BRI uses two 64Kbps B(earer) channels and one D(elta) channel to provide 128Kbps upload/download connection when used with an ISP that supports both B-channels. |
| Bridge | A device that enables you to link two networks together. Bridges are smart enough to know which computers are on which side of the bridge, so they only allow those messages that need to get to the other side to cross the bridge. This device improves performance on both sides of the bridge. |
| Bridge Tap | An extension to a local loop generally used to attach a remote user to a central office switch without having to run a new pair of wires all the way back. Bridged taps are fine for POTS but severely limit the speed of digital information flow on the link. |
| Bridgehead Server | A Microsoft Exchange Server computer that acts as an endpoint of a connection between two exchange sites. It is responsible for routing messages through the site connection. |
| Broadband | A term used to describe a high capacity network that can carry several services on the same line. Such as data, voice and video, DSL is broadband. |
| Browser | An application used on a PC to view web pages and transfer files over the internet. common browsers include Internet Explorer, Netscape Navigator, Mozilla, and Opera. |
| Browser Cache | The folder on your hard drive used as temporary storage for pages, pictures and other files downloaded from the internet. Windows Internet Explorer uses C:/Windows/Temporary Internet Files as its browser cache location in many cases.. Netscape Navigator and Communicator use a folder called Cache that can be found in various locations. |
| Browser Synchronization | The process of download new content for sites you have selected to view offline with Internet Explorer 5.x or higher or with DirecPC Turbo Webcast. |
| BSP | Boot Strap Processor |
| Buffer | A temporary storage area in a computer's memory, usually RAM, that holds recent changes to files and other information to write to the hard drive later. Because hard drives are relatively slow compared to RAM, buffers speed up performance. However, power outages generally wipe buffers clean; saving a file moves the information to the hard drive. Print buffers allow printing in the background while the user moves to another application or document. Some transmission protocols use buffers. Incoming data might be stored in a buffer until they are verified. |
| Burstable | Speeds that can exceed the CIR speed guaranteed with some broadband wireless services. It allows your computer to download as fast as the connection permits rather than being capped at a fixed maximum speed. |
| Bursty | Refers to the nature of Internet traffic. Because much Internet activity is the transfer of small amounts of data, a service that doesn't cap (limit) your speed can go fast when there is little traffic. |
| Bus | The circuitry on a motherboard that carries data from one component to another. The term usually refers to the circuits that connect the components to the CPU and RAM. Another type of bus is the expansion bus that connects the expansion cards to the CPU and RAM. This can also be a type of network topology in which network nodes are strung out along a single run of cable called a segment. 10Base2 and LocalTalk networks use a bus topology. |
| Button | An illustration that resembles a hardware button and is meant to be clicked on to produce an action. |
| Byte | A unit of data consisting of 8 bits. |
| CA | Certificate Authority. In Exchange advanced security, the CA is the central process that generates the public and private key pairs. The CA is responsible for creating and maintaining security key pairs and special certificates. Also see Certificate. |
| Cable Binder | A bundle of local loop wires that runs along telephone poles or underground from the Central Office (CO). |
| Cable Modem | A modem that uses your TV connection instead of a phone line to connect to the Internet. |
| Cache | (Pronounced cash). A bank of high speed memory set aside for frequently accessed data. The term "caching" describes the placement of data in the cache. Memory caching and disk caching are two common methods PC's use. Whenever data us accessed from or committed to main memory, a copy, along with the address, is saved in the cache with the associated main memory address. A memory cache maintains a list of frequently accessed data, complete with the address of that data. When the processor attempts to access an address, the cache checks its stores. If the memory cache holds the requested address (a cache hit), it returns the data to the processor. If not (a cache miss), a traditional memory access takes place. Disk caching works essentially the same way but uses conventional main memory instead of high-speed memory. These days, many microprocessors today have built in memory caches, which are called primary or L1 (Level 1) caches. External cache memory also can be added; this is called secondary or L2 (Level 2) caches. |
| Caching Server | A device used by most cable providers to store frequently requested pages at the local cable provider's head end, allowing users to get the page faster than if the Internet had to be accessed separately for each user's request for the same information. |
| Call Forwarding | Originally designed to allow a call to follow you to another number, This telephone company service can also be used to send to an Internet mail box to leave messages for a user whose phone is busy because their online. You must install software such as CallWave to use this feature with an Internet connection. |
| CAP | Carrierless Amplitude Phase. A modulation transceiver technology used in ADSL systems. |
| Capacity | The amount of information, measured in bytes that can be stored on a hard drive. Also known as storage capacity. |
| Carbon Copy | A function of an e-mail program that allows a sender to send a copy of an e-mail to additional recipients. |
| CAT3 | Category-3. An inexpensive form of unshielded twisted pair that is suitable only for 10Mbps 10BaseT networks. Shouldn't be used on new installations. |
| CAT5 | Category-5. The higher grade of 10BaseT cable that is suitable for 100Mbps 100BaseTX networks and gigabit Ethernet 1000BaseT networks. |
| Category-3 | An inexpensive form of unshielded twisted pair that is suitable only for 10Mbps 10BaseT networks. Shouldn't be used on new installations. Also known as CAT3. |
| Category-5 | The higher grade of 10BaseT cable that is suitable for 100Mbps 100BaseTX networks and gigabit Ethernet 1000BaseT networks. Also known as CAT5. |
| CAV | Constant Angular Velocity |
| CD | Compact Disk. Optical storage device for storing data and sound. Also see Platter. |
| CD-DA | Compact Disk Digital Audio |
| CD-I | Compact Disk Interactive |
| CD-R | CD Recorder, Compact Disk Recordable |
| CD_ROM | CD Reader, Compact Disk Read-Only Memory |
| CD-RW | CD Rewriter, Compact Disk ReWriteable. A drive that can write CD-rewriteable and CD-recordable media. It's great for making low cost backups of your computer. |
| CCD | Charge-Coupled Device. An instrument with semiconductors arranged so the output (electrical charge) from one semiconductor is the input of the next semiconductor. This type of array is used as the light-detecting component in many digital cameras, video cameras, and optical scanners. |
| Central Office | Also called the Central Switch, CO and Telephone Exchange. The location where telephone calls are switched to the rest of the telephone network. It's also where DSL and ISDN equipment must be installed to permit these services. |
| Central Switch | Also called the Central Office, CO and Telephone Exchange. The location where telephone calls are switched to the rest of the telephone network. It's also where DSL and ISDN equipment must be installed to permit these services. |
| CERT | Computer Emergency Response Team. CERT was established in direct response to the threat the internet worm created. Its mission is to study internet security vulnerabilities, handle computer security incidents, and publish security alerts. CERT is an excellent resource for information about viruses and how to handle them. See www.cert.org |
| Certificate | An authentication method used in security that contains information that actually authenticates a signed or sealed message. A certificate is only available to security enabled users. It primarily houses the user's public key and is transported through the Exchange network via the directory service. A certificate is meant to verify authenticity. Also see Certificate Authority, key. |
| Certificate Authority | In Exchange advanced security, the CA is the central process that generates the public and private key pairs. The CA is responsible for creating and maintaining security key pairs and special certificates. Also see CA, Certificate. |
| Certified Netware Engineer | A person who has studied and passed the official exam offered by Novell. Also known as CNE. |
| CGM | Computer Graphics Metafile. Designed by several standards organizations and ratified by ANSI (American National Standards Institute), CGM provides a standard method for exchanging vector graphics. CGM supports three different file formats: character encoding, for minimal size and speed of transmission; binary encoding, for speed of access during import into a graphics program; and clear text encoding for easy editing. Although bit maps can be embedded within the file, CGM is primarily a vector file. CGM has no built in compression but each of the three file formats produces different file sizes. |
| Channel | A path for digital transmission signals. Within digital services such as DSL, multiple channels can share the same pair of wires. Channels are created using multiplexers. |
| Chat | What you do on the network when you talk live with another network user. |
| Chat Room | A location on the internet where you can talk to a person or group of people in real time either via typing or voice if your computer is equipped with a microphone. |
| Checkbox | A small square that the user clicks on to indicate a choice. Similar in function to a radio button. |
| Checksum | A calculated value transmitted with data to check for errors in the transmission. |
| ChkDsk | A DOS command that checks the record-keeping structures of a DOS disk for errors. |
| CIDR | Classless Internet Domain Routing. In response to the limitations of A, B and C classes of IP Addresses, InterNIC implemented CIDR (which is pronounced "cider"). CIDR allows IP Addresses to be broken down into smaller subnets than the class C network, with 256 IP Addresses. CIDR networks are described as slash x networks, where x represents the number of bits in the IP address range. |
| CIP | Client Installation Point. A shared directory on a file server to which users can connect in order to install the Microsoft Exchange Client. Also see Network Share. |
| Ciphertext | Encrypted or encoded data. Data is changed into this code for security reasons; it isn't readable without the appropriate password to decode it. |
| CIR | Committed Information Rate. The minimum speed guaranteed for a connection with some broadband wireless Internet services. |
| Circuit | A path thru a network from source to destination and back. In a circuit switched network, this path uses a fixed route and a fixed amount of bandwidth for the duration of the connection between the two endpoints. |
| Clawhammer | AMD processor that will be the first to bring 64 bit computing to the desktop. 2003/2 |
| Clean Rooms | A closed-in area containing sensitive equipment. The air is filtered to keep out dust and other particles, and people wear protective clothing to avoid inadvertently contaminating the equipment. The computer facilities of many companies, particularly those with important data such as customer accounts, are set up as clean rooms, as are areas where highly sensitive equipment such as microprocessors are made. |
| CLEC | Competitive Local Exchange Carrier. A competitor to ILECs offering telecommunications service. As for DSL service, the CLECs offer data communications service. |
| Click | What you do in Windows to get things done. You click on icons, buttons, links, etc. |
| Client | In a LAN (Local Area Network), a computer that retrieves information from or uses resources provided by the server. Unlike a "dumb" terminal used to access information from a mainframe in older systems, a client is capable of running applications and is a complete computer system in its own right. More generally, a client is a program or task that calls upon a service provided by another program or computer. In short, a computer that has access to the network but doesn't share any of its own resources with the network. |
| Client Installation Point | A shared directory on a file server to which users can connect in order to install the Microsoft Exchange Client. Also see Network Share. |
| Client-Server | A computer system for which part of the work happens on a client computer and part of it happens on a server computer. To be a true Client-Server Application, real work must be done on the server. Any server based network can loosely be called client-server but in a true client-server system, at least part of the real work is done on the server not just file access. An example of this would be a client-server database, a database query is processed on the server and just the results of the query are sent back to the client computer. |
| Client-Server Architecture | In a client-server system, the client sends requests to a server, the server carries out the instructions and the results are sent back to the client. Client-server is the underlying architecture of Microsoft Exchange Server. Also see Shared File Architecture. |
| Cluster | A group of disk sectors (usually two to eight) the operating system or disk controller treats as one entity. It sometimes refers to a group of computer terminals connected to a computer system or controller, as well. Also see Allocation Unit. |
| CLV | Constant Linear Velocity |
| CM | Corrective Maintenance. Maintenance actions carried out to restore a defective item to a specified condition. 2. Tests, measurements, and adjustments made to remove or correct a fault. |
| CMC | Common Message Calls. A set of 10 high level functions for quick and easy implementation of simple messaging. |
| CMOS | Complementary Metal Oxide Semiconductor. An electronic component used for random-access memory (RAM) and fast data switching. CMOS semiconductors are made of two metal-oxide, field effect transistors for high speed and low power use. These devices can be damaged by static electricity. |
| CO | Central Office. A telephone company facility within which all local telephone lines terminate and which contains the equipment required to switch customer telecommunications traffic. For DSL service, DSLAM equipment is typically set up at the CO to support DSL service for lines terminating at the CO. |
| Coaxial Cable | A wire conductor surrounded by a cylindrical conductor and either insulating rings or dielectric material, the entire cable is covered with a shield that blocks interference. Extremely durable, coaxial cabling lets users simultaneously transfer voice, data, and video signals. Available in thin (for 10Base-2 networks) and thick (for 10Base-5 networks) versions, thin coaxial is the most commonly used cabling. Providing more capacity than twisted-pair cabling, coaxial cable is also more expensive. |
| CODEC | Compressor / Decompressor. Any technology used to compress and decompress data, which can be done with hardware, software or a combination of both. Different technologies perform this in different ways. For example, MPEG (Moving Picture Experts Group) is a video codec that compresses full-motion digital video; it requires special hardware for decompression. |
| Cold Boot | A cold, also known as a cold start, is when you turn on a computer after it's been shut off. |
| COM | Communications Port. Serial communications outlets, or ports , used to connect devices such as modems and serial printers to your computer. |
| COM1 | The first communications port on a computer. |
| COM Port | Also called a RS-232 Serial Port. This port is used for most external analog modems and for most ISDN TAs. USB is preferred when available. |
| Commissioning | DirectPC's term for setting up your directPC satellite modem and account. |
| Common Message Calls | A set of 10 high level functions for quick and easy implementation of simple messaging. |
| CompactFlash | A type of removable storage card (also known as flash memory) for digital cameras. Many digital cameras accept CF cards but others use a different memory type such as smart media card or a Sony Memory Stick. CF cards come in two varieties, Type I and Type II. Cameras designed for CF Type I can only use the 5mm-thick Type I cards. Cameras designed for CF Type II can use either Type I or the newer Type II (9mm-thick) cards. |
| Compressed File | See "Compression", "Zip" |
| Compression | Any method of condensing information so it can be stored in less space or transmitted in less time. Many large graphics and sound files are compressed so they can be downloaded faster. |
| CompTIA | Computing Technology Industry Association |
| Computer Crash | Popular expression, used about almost any computer or hard disk problem. See also disk crash. |
| Computer Name | A unique name assigned to each computer on a network. |
| Computer Virus | A dangerous computer program with the characteristic feature of being able to generate copies of itself, and thereby spreading. Additionally most computer viruses have a destructive payload that is activated under certain conditions. |
| Config.sys | A text file that specifies the drivers (software that lets computers communicate with hardware) and system parameters used in MS-DOS and OS/2. Config.sys controls some aspects of the OS' (operating system's) behavior, and it contains commands about how to do things such as work with new hardware or adjust memory. This file is read when the OS loads, and the instructions in the file are carried out by the OS loader. The file can be changed using any text editor. |
| Connector | A component of Microsoft Exchange that routes messages between Microsoft Exchange Server sites and other messaging systems. For example, the Internet Mail connector enables Microsoft Exchange users to send and receive messages with other users on the Internet. Also see Address Space. |
| Console | In NetWare, the file server's keyboard and monitor. Console commands can be entered only at the server console. |
| Console Operator | A NetWare user working at the file server's console. |
| Container | In the Microsoft Exchange Administrator program, a container is an object that contains other objects. For example, the recipients container is composed of recipient objects. |
| Control Panel | A Windows application that enables you to configure various aspects of the Windows operating system. |
| Conventional Memory | The first 640Kb of memory on a DOS based computer. |
| Cookie | A small data file stored on your computer by web browsers to help personalize your surfing experience. They are also used to identify you when you revisit a web site. |
| Corrupt Copy | Some times whilst transferring data from a damaged disk, the damaged disk releases the expected amount of raw data but in a seemingly random order. Such a copy is worthless. The problem is due to a physical damage to the disk, which causes errors in the location/addressing information. |
| CPE | Customer Premises Equipment. A telecommunications term that refers to any equipment located at the customer's premises. DSL modems, routers and bridges are CPE. |
| CPU | Central Processing Unit. The computer's control unit or microprocessor, it's "brain". The CPU, a silicon chip often enclosed in a plastic casing, interprets and carries out instructions. |
| CRC | Cyclical Redundancy Checking |
| Crimp Tool | A special tool used to attach connectors to cables. Most tool kits should have one. |
| CrossFireX | CrossFireX allows you to link up to four ATI GPUs to produce a single video output. While regular SLI, 3-WaySLI, and Quad SLI let you link two, three or four nVidia GPUs. You will need to make sure you have enough PCIe x16 slots in your case to handle all the cards and that your power supply can provide the required power for them. |
| Crosstalk | The interference induced on a signal on one line that is caused by the transfer of energy from a second line located near the first. Crosstalk is a factor in the delivery of different types of DSL service within the same cabling bundle. |
| CRT | Cathode Ray Tube. The display screen used in most televisions and standard computer monitors. An electron beam moves across the back of the screen, lighting up phosphor dots inside the class tube, which causes an image to be displayed. |
| Crash | An unexpected (and usually very annoying) shutdown either of a program or the whole system, which usually results in data loss. |
| Crush K8 | Chipset from nVidia designed to take advantage of Clawhammer. |
| CSMA/CA | Carrier Sense Multiple Access with Collision Avoidance |
| CSMA/CD | Carrier Sense Multiple Access with Collision Detection. This is the traffic management technique used by Ethernet. A network transmission scheme in which multiple network devices can transmit across the cable simultaneously. |
| CSNW | Client Services for NetWare |
| CSRC | Computer Security Resource Center. The National Institute of Standards and Technology maintains CSRC, which is part of the U.S. Department of Commerce. The site maintains an up-to-date list of links to virus resources around the world, as well as its own security bulletins detailing techniques and guides for managing your computer system. See csrc.nist.gov/virus |
| CSU/DSU | Channel Service Unit / Data Service Unit |
| CTS | Clear to Send. A hardware signal that indicates the receiving unit is ready to accept the information from the sending unit. |
| Custom Recipient | A recipient in a foreign system whose address is specified in the address book. For example, if your Microsoft Exchange system is connected to a different email system by way of the Internet Mail connector, the recipients in that email system have custom recipient address entries in the address book. |
| Cut and Paste | Copying text, images, etc from a page into a temporary storage area [your clipboard] and then pasting it into another document or into another application. |
| Cyberspace | A term often used to refer to the Internet or that mysterious place where you send, receive and access data via your Internet connection. |
| Cylinder | On a disk, all tracks with the same radius are referred to as a cylinder. |
| Daisy Chain | A means of connecting computer components, in which the first component is connected to the second, which is connected to the third and so on. Hubs can be daisy chained in 10baseT and 100baseT Ethernet systems. |
| DAP | Directory Access Protocol |
| DAT | Digital Audio Tape. A type of tape often used for network backup. |
| Database | A collection of data stored and formatted in a way that makes it easy to retrieve the information. |
| Data Block | A series of data elements handled as one unit. Typically a data block on disk is 512 bytes long (synonymous with sector). On tape the block size is normally greater and variable. |
| Data CLEC | A Competitive Local Exchange Carrier that focuses on IP data communications links and doesn't provide traditional voice telecommunications. |
| Data Compression | Any method of condensing information so it takes up less storage space or transmits in less time. Many large graphics and sound files are compressed so they can be downloaded faster. Also called data compaction. |
| Data Destruction | Removal/destruction of information stored on a storage medium. |
| Data Link Layer | The second layer of the OSI model, responsible for transmitting bits of data over the network cable. |
| Data Recovery | The salvaging of data stored on damaged media , such as magnetic disks and tapes. Many companies specialize in data recovery service and their specialists and engineers can often restore a surprisingly high percentage of the data on damaged media. |
| DBMS | Database Management Systems |
| DC | Direct Current. An electrical current that flows in one direction. For example, batteries are a direct current source. |
| DCD | Digital Color Decoder. Measured by Bits and also known as Color Depth, this is the ability of the scanner's hardware to translate the scanned image's digital data into color. |
| DCE | Data Communications Equipment. Data communications equipment; the technical term for modem-to-modem connection. |
| D-Channel | ISDN's Delta Channel, which is used for signaling and making connections. |
| DCLEC | Digital or Data Compression Local Exchange Carrier. A type of CLEC that competes with other telephone companies for digital services. |
| DDE | Dynamic Data Exchange. A two-way connection between multiple programs that lets the programs actively exchange data while both programs are running. This exchange of data without user intervention is known as conversation. Available with Windows and OS/2, this feature lets users use one program to manipulate data in another program. |
| DDR SDRAM | Double-Data-Rate Synchronous Dynamic Ram. |
| DDS | Digital Data Service, Digital Data Storage |
| Decode | Transforming encoded information into information that is readable to a program or a user. |
| Decompression | The process of restoring compressed data to its original form. This task must be accomplished with a program that recognizes the format of the compressed file. |
| Decryption | The process of translating data back into its original language. |
| Dedicated Line | A phone line that isn't shared by a phone and a computer. |
| Dedicated Server | A computer used exclusively as a network server. Also refers to a server used exclusively as a single website server. |
| Deerfield | Intel's low cost 64 bit processor that will target servers. |
| Default | The predetermined configuration of a hardware device or software application. |
| Default Gateway | The address that the IP uses if the destination address is not on the local subnet. The default gateway is usually the router's IP address. |
| Defect Management | A general methodology of eliminating data errors on a recording surface by mapping out known defects on the media. The defective areas are rendered inaccessible, so that when information is written to the disk, it is stored to non-defective locations on the disk. See G-List and P-List. |
| Defragment | Reorganizing a hard drive or diskette so individual applications or files aren't fragmented or scattered. This fragmentation occurs because of the way information is stored in little pieces on a disk. |
| Degausser | Equipment employing a strong magnetic field to perform data erasure. |
| Delayed Write | A disk caching technique in which data written to disk is placed in cache memory and actually written to disk later. |
| Delegate | In Microsoft Exchange, a delegate is a person with permission to manage and/or send email for another user. |
| Deleted File | When a file is deleted using the operating system command or Delete-key, it is only the reference to the file that is deleted. The space previously occupied by the file content will be free to be used by any new file. It is possible to recover the deleted file until a new file has occupied the space. |
| Delivery Receipt | A notice confirming that a message has been delivered to its intended recipient. Also see Read Receipt. |
| Demarcation Point | The point at the customer premises where the line from the telephone company meets the premises wiring. From the demarcation point, the end user is responsible for the wiring. |
| Demodulation | The process of interpreting the variations of a modulated carrier signal into digital transmissions. |
| DES | Data Encryption Standard |
| Desktop | In a GUI, a desktop refers to the files and programs loaded on the computer. The desktop contains pictures, also known as icons, that show cabinets, files, folders and programs. You can arrange the icons on the desktop by clicking and dragging the objects. |
| Device Driver | A program that lets a hardware peripheral, known as a device, communicate with a computer. Some device drivers, such as those for the monitor and keyboard, come with the computer, while others, such as those for a CD-ROM drive or sound card, came packaged with their corresponding devices. Users can obtain device drivers, as well as updates for the device drivers, from the component's manufacturer. |
| DHCP | Dynamic Host Configuration Protocol. A protocol that allows IP addressing information to be dynamically assigned by a server to clients on an as needed basis. IP addresses for a network are stored in a pool of available IP addresses, which are allocated when a computer on the network boots up. The DHCP server functionality is built into most DSL routers. |
| Dial-Up | To establish a temporary connection with a network or another computer using a modem connected to a telephone line. Dial-up access usually requires a software application in addition to the modem and phone line. |
| Dial-Up Modem | Converts digital computer signals to analog telephone signals and back. It is the common type of modem supplied with most computers; also called a dial-up modem. |
| Dial-Up Networking | Used in Microsoft Windows 95, 98, NT and 2000 for making PPP dial-up modem connections to the Internet. If you have a PCI or USB DSL modem that uses PPP over DSL, you need to use DUN (Dial-Up Networking). |
| Differential Backup | A type of backup where only the files that have changed since the last full backup are backed up. |
| Digital | The opposite of analog. Data is represented by 0 (off or low) and 1 (on or high). Computers must use an analog modem to convert digital data into analog form for transmission over ordinary phone lines. |
| Digital Camera | A digital camera stores pictures digitally rather than on film like a traditional camera. |
| Digital Color Decoder | Measured by Bits and also known as Color Depth, this is the ability of the scanner's hardware to translate the scanned image's digital data into color. Also see DCD. |
| Digital Loop Carrier | A technique for extending voice-grade telephone lines a longer distance from a telco's central office without expensive signal boosters. It also is used to reduce the need to re-cable to add capacity. A digital loop carrier connection isn't suitable for high-speed connections such as ISDN or DSL. |
| Digital Media Adapter | Device from Intel that will wirelessly connect PCs to televisions. |
| Digital Signature | An advanced security feature of Microsoft Exchange that enables users to verify the source of messages and to verify that the contents of the message have not been modified during transit. Also see Signing, Key, Encryption. |
| Digital Subscriber Line | Technology used to transmit digital data on regular copper phone lines. DSLs can be used to provide connections to the Internet or LANs (local area networks) or for videoconferencing. The technology deferrers from ISDN (Integrated Services Digital Network) lines in that it can send analog and digital over the phone line. ISDN is digital only and has to convert analog voice phone calls to digital signals. With DSL, the analog voice phone calls and digital signals can coexist on the same wires. |
| Digital Zoom | Most digital cameras aimed at consumers give users the option of using either optical or digital zoom capabilities. Many models offer both types. Digital zoom is less preferable because it requires that the camera's embedded software only take a section of an image and magnify it to full size. Digital zoom is not a true zoom. |
| DIMM | Dual Inline Memory Module |
| DIP Switch | A bank of switches used to configure an older adapter card. Modern cards configure themselves automatically, so DIP switches aren't needed. |
| DirecDuo | A satellite dish used with DirecPC and/or DirecTV. The same dish can support either or both services at once. |
| DirecPC | A broadband solution that uses geo-synchronous satellite technology. It was developed by Hughes Network Systems. |
| Directory | (1) An organized catalog of files and
subdirectories contained on a hard drive or removable disk. The main
directory is called the root directory; all subdirectories stem from it.
Directories are found in the hierarchical file schemes common to most
operating systems. Such file systems store data as if in a file
cabinet. The root directory is the file drawer, subdirectories are
the folders in that drawer and individual documents are files in those
folders. File names can be organized within a directory in many
ways, such as alphabetically and by type, size or date. In graphical
interfaces, such as Windows, folders can be displayed as icons. (2) The Microsoft Exchange directory stores all the information about an organizations resources and users such as recipients, sites and servers. Other Exchange components use the directory to address and route messages. On an Exchange server, the directory, also called Directory Service (DS), is a Windows NT service [MSExchangeDS]. It is one of the four core Microsoft Exchange Server services. Also see Information Store, Message Transfer Agent, System Attendant. |
| Directory Object | In Microsoft Exchange, a record in the directory such as a mailbox, a server or a distribution list. Every object has properties that can be defined. |
| Directory Replication | The process of updating the directories of all Microsoft Exchange servers within and between Exchange sites. |
| Directory Replication Bridgehead Server | A Microsoft Exchange server, which is a specialized bridgehead server, that acts as the endpoint of a directory replication connection between its site and a remote site. This server requests directory updates from the remote Exchange site. |
| Directory Service | The Microsoft Exchange directory stores all the information about an organizations resources and users such as recipients, sites and servers. Other Exchange components use the directory to address and route messages. On an Exchange server, the directory, also called Directory Service (DS), is a Windows NT service [MSExchangeDS]. It is one of the four core Microsoft Exchange Server services. Also see Information Store, Message Transfer Agent, System Attendant. |
| Directory Synchronization | In Microsoft Exchange, the process synchronizing an Exchange server directory with the directories from MS Mail systems either PC or AppleTalk. On an Exchange server this is managed by a Windows NT/2000/2003 service, the Directory Synchronization Agent (MSExchangeDXA). |
| DirecTV | A satellite TV system developed by Hughes Network Systems that can coexist with DirecPC when a DirecDuo dish is used. |
| Disk |
(1) Used synonymous with hard disk. (2) Can be used about any storage media where the actual media is a circular disc - hard or soft kernel, magnetic or optical technology. (3) Circular platters. The actual media. See Platter. |
| Disk Crash | As a popular expression this term is used about almost any problem with the computer or the hard disk. More correctly it should be used synonymous with head crash. |
| Distribution List | In Microsoft Exchange, a distribution list (DL) is a collection of recipients commonly addressed together as a single recipient. A DL makes it easier and more convenient to manage and address multiple recipients. Administrators can create DLs that are available in the address book. Users can create DLs and add them to their personal address book. |
| Dithering | A graphic technique that uses a mixture of colored or shaded dots to create a new color. For example, the ratio of blue dots to yellow dots in a contained area will determine the shade of green. |
| DIX | Digital / Intel / Xerox |
| DL | Distribution List. In Microsoft Exchange, a distribution list (DL) is a collection of recipients commonly addressed together as a single recipient. A DL makes it easier and more convenient to manage and address multiple recipients. Administrators can create DLs that are available in the address book. Users can create DLs and add them to their personal address book. |
| DLC | Digital Loop Carrier. A telecommunications structure deployed where ever an ILEC needs more capacity. DLCs consist of a box containing line cards that concentrate individual lines within a given area and then send the traffic over a high speed digital connection. DLCs are commonly deployed in new buildings, office parks and residential subdivisions. |
| DLL | Dynamic Link Library. An executable subroutine stored as a file separate from the programs that use it. DLLs, which are loaded into memory only when needed, are used extensively in Windows and OS/2. The DLL file name extensions are .DLL, .DRV, and .FON. |
| DLT | Digital Linear Tape |
| DMA | Direct Memory Access. A means of transferring data from a storage device, such as a hard drive or a tape drive, to memory without passing the information through the processor. |
| DME | Distributed Management Environment |
| DMT | Discrete Multi-Tone. ADSL modulation technique standardized by the ANSI T1E1.4 standard and used in ADSL systems. |
| DNAL | Dedicated Network Access Line |
| DNAR | Directory Number Analysis Reporting |
| DNC | Dynamic Network Controller |
| DNS | Domain Name System. The name resolution service for IP addresses that provides the friendlier text-based addresses for Internet resources. DNS uses a distributed data base containing FQDNs and addresses. Also the naming system used on the internet, where a network is given a domain name and individual computers are given host names (computer names). |
| DNS Service | The configuration of user friendly text domain names to IP addresses by an ISP using the Domain Name System. |
| DOCSIS | Data Over Cable Systems Interface Standard. Also known as CableLabs Certified Cablw Modems. A standard for cable modems that allows the same cable modem to be used on any system that supports the DOCSIS standard. |
| Domain | In Windows NT/2000 network, one or more network servers that are managed by a single network directory. Minimally composed of a Windows NT/2000 primary domain controller. Also can mean, in the Internet, a name assigned to a network. |
| Domain Controller | A windows NT/2000 domain controller is the Windows NT/2000 server computer that maintains the security database for a domain and authenticates domain logons. Windows NT/2000 domains can have one primary domain controller (PDC) and one or more backup domain controllers (BDC). |
| Domain Name | The identifying title given to a system of computers, usually including the top domain and all of its subdomains. For example, a domain name, such as socrates.nd.edu, indicates that Socrates network is found at the University of Notre Dame (nd), which is an educational institution (edu). The user friendly text name used instead of a numeric IP address for an Internet address. |
| Domain Name Server | On the Internet, a central computer to which all other computers of a domain or sub-domain are ultimately linked. The domain name server translates the domain name into an Internet Protocol (IP) address to direct information from within the domain to other computers on the Internet. It also translates IP addresses into domain names. |
| Domain Name System | The name resolution service for IP addresses that provides the friendlier text-based addresses for Internet resources. DNS uses a distributed data base containing FQDNs and addresses. Also the naming system used on the internet, where a network is given a domain name and individual computers are given host names (computer names). |
| DOS | Disk Operating System. An operating system designed for early IBM-compatible PC's. |
| Dot Matrix Printer | Once the mainstay printer for PC's, they use multiple pins striking the printer ribbon to print but dot matrix printers have given way to laser printers and inkjet printers. High speed matrix printers still have a place on the network, though and matrix printers have the advantage of being able to print multiple part forms. |
| Download | The process of transferring a file or data from one PC or device to another. A download can also be carried out over the Internet. |
| Download Manager | A type of program that speeds up downloads and can schedule downloads for off-peak periods. |
| Downstream | The direction of data flow on a data communications link that occurs from the network down to the user. In the case of Internet access, downstream is the capacity or speed of data flowing from the Internet to the end user's PC or LAN. |
| Downtime | The opposite of uptime. When your Internet service or computer isn't working. |
| DPCM | Differential Pulse Code Modulation |
| DPCS | Digital Personal Communications Services. See PCS. |
| DPI | Dots Per Inch. Also known as Pixels Per Inch (PPI). This is the unit of measurement for the density of the square inch of an image. The higher the DPI, the higher the quality of the image. |
| DQDB | Distributed Queue Dual Bus |
| DR | Delivery Receipt. A notice confirming that a message has been delivered to its intended recipient. Also see Read Receipt. |
| DRAM | Dynamic Random Access Memory |
| DRBS | Directory Replication Bridgehead Server. A Microsoft Exchange server, which is a specialized bridgehead server, that acts as the endpoint of a directory replication connection between its site and a remote site. This server requests directory updates from the remote Exchange site. |
| Drive |
(1) Often used synonymously with disk. (2) For removable media, the term is used about the fixed housing unit. Examples: floppy drive, tape drive. |
| Driver | A program that lets a hardware peripheral, known as a device, communicate with a computer. Some device drivers, such as those for the monitor and keyboard, usually come with the computer, while others, such as those for a CD-ROM drive or a sound card, come packaged with their corresponding device. Device drivers, as well as updates for the device drivers, also can be obtained from the manufacturer of the component. |
| DriveSpace | A disk compression feature of Windows 9x, Me, and DOS 6.2. DriveSpace compresses file data so that files require less disk space. This compression increases the effective capacity of the disk, quite often by a factor of 2:1 or more. |
| Drop Damage | Shock to a hard drive may cause the platters to become displaced, or damage to heads or the magnetic coating of the platters. Dropping a hard drive may also damage to the mechanics within the drive such as the motor. As a consequence, the drive is unable to position the heads correctly along the recorded signals. A shock may later lead to a head crash. |
| Drop Down Menu | A list of choices that drops down when you select its key word. Almost every modern application has a drop down menu called "File". |
| DS | Directory Service. The Microsoft Exchange directory stores all the information about an organizations resources and users such as recipients, sites and servers. Other Exchange components use the directory to address and route messages. On an Exchange server, the directory, also called Directory Service (DS), is a Windows NT service [MSExchangeDS]. It is one of the four core Microsoft Exchange Server services. Also see Information Store, Message Transfer Agent, System Attendant. |
| DS1 | Digital Signal 1. The signaling portion of the T-1 carrier. It includes 24 64Kbps (DS0) signals. |
| DS3 | Digital Signal 3. The signaling portion of the T-3 carrier. It includes 28 DS1 signals, which equals 672 64Kbps (DS0) signals. |
| DSL | Digital Subscriber Line. Technology used to transmit digital data on regular copper phone lines. DSLs can be used to provide connections to the Internet or LANs (local area networks) or for videoconferencing. The technology deferrers from ISDN (Integrated Services Digital Network) lines in that it can send analog and digital over the phone line. ISDN is digital only and has to convert analog voice phone calls to digital signals. With DSL, the analog voice phone calls and digital signals can coexist on the same wires. |
| DSLAM | Digital Subscriber Line Access Multiplexer. |
| DSL Bridge | A device that combines one or more networks into a single seamless network. Also referred to as a DSL modem. |
| DSL forum | This industry organization is made up of computer and telecommunication companies that define DSL standards for submission to standards bodies. This group is responsible for accelerating ADSL technologies, products and services as well as promoting the technology. |
| DSL Modem | A device that combines one or more networks into a single seamless network. A common term used for a DSL bridge.. |
| DSR | Dynamic Sector Repair(ing) |
| DTE/DCE | Data Terminal Equipment / Data Communications Equipment.
Data terminal equipment; refers to the RS-232 serial port used to
connect external analog modems or external ISDN TAs to a computer. Data communications equipment; the technical term for modem-to-modem connection. |
| Dual-Band LANs | LAN access points that simultaneously support 802.11a and 802.11b wireless networking. These are available now but expect to see them proliferate. |
| Dumb Terminal | In the day of mainframe computers, a dumb terminal was a monitor and keyboard attached to the central mainframe. All the computing work occurred at the mainframe. The terminal only displayed the results and sent input typed at the keyboard back to the mainframe. |
| DUN | Dial-Up Networking. Used in Microsoft Windows 95, 98, NT and 2000 for making PPP dial-up modem connections to the Internet. If you have a PCI or USB DSL modem that uses PPP over DSL, you need to use DUN (Dial-Up Networking). |
| DVD | Digital Versatile Discs. A data storage media with platters similar to a CD. The storage capacity is much higher then for a CD. DVD is used for storing video, sound and data. (Digital Video Discs) |
| DVD-R | Digital Versatile Disc Recording. As a result of copy protection issues there are two types of DVD-Rs. DVD-R for Authoring is used to make master discs for replication. DVD-R for general Purpose includes copy protection (to prevent backup of encrypted commercial DVDs). DVD-R 'authoring' and DVD-R 'general' can read each others format but they cannot write to each other's format. Most consumer DVD-R burners use 'general purpose' discs. DVD-Recordable has shown high compatibility (85% - 90%), depending on who you ask, with standalone DVD players. |
| DVD+R | DVD+R is a write-once, dye based medium, like DVD-R, and has similar compatibility. DVD+R was introduced after DVD+RW and cannot be written on the first generation of DVD+RW drives without modification. |
| DVD-RAM | Digital Versatile Disc Random Access Memory. DVD-RAM is a very robust data storage solution, theoretically allowing 100,000+ rewrites per disc. It has outstanding recording features but is not compatible with most DVD-ROM drives and DVD-Video players. DVD-RAM functions like a removable hard disk with fully integrated OS-level random read/write access in both Windows XP (with FAT 32) and MAC OS X (with FAT 32 or HFS+), as well as on-the-fly write verification. Current drives use 4.7 GB discs (or double sided 9.4 GB discs). DVD-RAM discs are traditionally housed within sealed cartridges. Newer Type II and Type IV cartridges can be opened however, an important feature for those who wish to read these discs in DVD-RAM compatible DVD-ROM drives or standalone DVD players. In addition, some DVD-RAM discs are now sold without cartridges. |
| DVD-ROM | Digital Versatile Disc Read-Only Memory |
| DVD-R/DVD-RW | DVD-R/DVD-RW. These drives are the most common drives currently, with both PCs and MACs. The low cost of DVD-R/RW makes it an excellent solution for backup purposes. Most standalone DVD players will read DVD-R and some will read DVD-RW as well, although the compatibility rate is significantly lower with DVD-RWs. DVD-R/RWs are now commonly called "DVD Minus R/RWs" or "DVD Dash R/RWs" to distinguish them from the competing "Plus R/RW" format from the DVD+R/RW Alliance. |
| DVD+R/DVD+RW | DVD+R/DVD+RW. These formats from the DVD+RW Alliance, are referred to simply as +R and +RW. Technically, "DVD" is not part of their names because they are not approved by the DVD Forum. In Reality, these formats are very similar to DVD-R and DVD-RW in design, usage, reliability and player/recorder compatibility and not surprisingly, are commonly called DVD+R/W. DVD+R/W supports single sided 4.7 GB DVDs (DVD-5) and double sided 9.4 GB DVDs (DVD-10). DVD+RW drives read DVD-ROMs and CDs and usually read DVD-R/RWs but do not read or write DVD-RAM discs. DVD+RW drives also write CD-Rs and CD-RWs. |
| DVD-RW | DVD Read Write is a rewritable (re-recordable) DVD disc for movies and data. DVD-RW media use phase change technology and can be rewritten as many as 1,000 times under ideal conditions. DVD-RW was the first recordable DVD format compatible with standalone DVD players and it is also compatible with approximately 60-70% (again depending on who you talk to) of DVD Players and DVD-ROMs. Most DVD-RW recorders also record to DVD-R. However, the reverse is often not true. |
| DVD+RW | DVD+RW differs from DVD-RW in that it uses lossless linking and both CAV and CLV writing. The DVD+RW uses phase-change media with a high frequency wobbled groove to eliminate linking sectors. This, plus the option of no defect management, makes recorded DVD+RW discs compatible with many existing DVD readers. DVD+R/RWs use CLV format for sequential video access (read at CAV by the drive) and CAV format for more uniform random access in interactive data applications. DVD+R discs can only be recorded in CLV mode and only CLV-formatted discs can be read in standard DVD drives and players. One potential future advantage of the +RW format is the optional Mount Rainier drag-and-drop file access support (also known as +MRW) planned for future versions of Windows. However, current drives do not support Mount Rainier on DVD+RW. |
| DXF | Drawing Exchange Format. Developed by AutoDesk for use with its AutoCad program, this may be one of the most used vector file formats. DXF is a text based format that includes support for 3D objects, curves, text and associative dimensioning. As a text file, DXF is easy to parse (divide into small parts for translating) and many graphics programs include support for DXF format. DXF stores data in noncompressed format, so files tend to be large. As its name suggests, DXF is used primarily for exchanging technical drawings between CAD programs. |
| Dynamic IP Addressing | An IP address is assigned to the client for the current session or some other specified amount of time. This form of IP addressing is used by DSL services targeted at the consumer market and typically doesn't support any Domain Name System Service. |
| Dynamic RAS Connector | A Microsoft Exchange Server messaging connector That routes messages between Exchange sites using Windows NT/2000 Remote Access Services (RAS). Also see Messaging Connector. |
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