Glossary of Networking Terms Copyright © 2000 SYBEX Inc., Alameda, CA. www.sybex.com 578 Glossary of Networking Terms 10Base-2 An implementation of Ethernet that specifies a 10Mbps sig- naling rate, baseband signaling, and coaxial cable with a maximum segment length of 185 meters (approximately 607 feet). 85% policy A Web site design policy that encourages the use of technolo- gies that will reach many people but not let the stragglers drag functionality down for other viewers. The Web site is designed so that the majority of Internet users can view its content. abend Short for ab normal end . Novell’s term for a server crash. ABEND.LOG The log file in the SYS:\SYSTEM directory on a NetWare 4.11 or later server that records all abends that have occurred on a NetWare server, including detailed information regarding the abend. access control Any system that keeps people from accessing resources they don’t need. If they can’t access it, they can’t steal it. Access Control List (ACL) The list of rights an object has to resources in the network. Also a type of firewall. In this case, the lists reside on a router and determine which machines can use the router and in what direction. access log A Web server log file that indicates who has accessed which resource. The access log records the IP address of the accessing station, the time and date of the access, which file was accessed, and the protocol used to access it. ACK See acknowledgment. acknowledgment (ACK) A message confirming that the data packet was received. This occurs at the Transport layer of the OSI model. ACL See Access Control List. active detection A type of intruder detection that constantly scans the network for possible break-ins. active monitor Used in Token Ring networks, a process that prevents data frames from roaming the ring unchecked. If the frame passes the active monitor too many times, it is removed from the ring. Also ensures that a token is always circulating the ring. Copyright © 2000 SYBEX Inc., Alameda, CA. www.sybex.com Glossary of Networking Terms 579 Active Server Pages (ASP) The server-side scripting solution for Microsoft Web servers—mainly, Internet Information Server (IIS). adaptive content policy A Web site design policy in which Web sites don’t necessarily have to choose between accessibility and glamour. Instead, sites can deliver advanced features to clients that can use them and standard features to clients who can’t use advanced features. In this way, the whole audience is well served. Writing the Web site to work in this way, however, adds complexity and often cost. Adobe Acrobat A file format that is used on the Internet to distribute files that contain graphics and text in a specified layout. Acrobat allows users on diverse platforms to view (and in its latest version, annotate) documents that incorporate text, graphics, hyperlinks, and complex layouts. It’s better than HTML because the publisher has absolute control over how the publication looks on users’ machines. Acrobat files carry a .PDF filename extension. American Standard Code for Information Interchange (ASCII) The standard code used to convert decimal numbers used during computer com- munications into characters, numbers, and symbols for display on screen. antivirus A category of software that uses various methods to eliminate viruses in a computer. It typically also protects against future infection. See also virus. Application layer Layer seven of the OSI model; the Application layer deals with how applications access the network and describes application functionality, such as file transfer, messaging, and so on. application log Windows NT log file, viewable in the Event Viewer, that is used to keep track of events for network services and applications. application server Any server that hosts a network application. ARCNet The Attached Resource Computer Network, which was devel- oped by Datapoint Corporation in the late 1970s as one of the first baseband networks. It can use either a physical star topology or a bus topology. Copyright © 2000 SYBEX Inc., Alameda, CA. www.sybex.com 580 Glossary of Networking Terms ARP table A table used by the ARP protocol. Contains a list of known TCP/IP addresses and their associated MAC addresses. The table is cached in memory so that ARP lookups do not have to be performed for frequently accessed TCP/IP and MAC addresses. See also Address Resolution Protocol; media access control; Transmission Control Protocol/Internet Protocol. ASCII See American Standard Code for Information Interchange (ASCII). ASP See Active Server Pages (ASP). Asynchronous Transfer Mode (ATM) A connection-oriented network architecture based on broadband ISDN technology that uses constant-size 53-byte cells instead of packets. Because cells don’t change size, they are switched much faster and more efficiently than packets across a network. AT command set A set of modem initialization commands developed by the Hayes company for their modems, so named because each command begins with AT . See also modem initialization commands. ATM See Asynchronous Transfer Mode. Attachment Unit Interface (AUI) port On some NICs, a port through which the NIC can be connected to different media types by using an external transceiver. Audio Visual Interleaved (AVI) files A video file format that has support for full-motion video and animation with sound. Developed for the Windows environment by Microsoft, AVI files usually have .AVI filename extensions. auditing A system of record keeping in which special software takes notes of what is happening on a network and why and allows administrators to look at those notes (called log files) later. authentication The process of verifying that a person (or a piece of soft- ware, in situations where programs share information without human inter- vention) is who he claims to be. AVI files See Audio Visual Interleaved (AVI) files. B channel See Bearer channel. Copyright © 2000 SYBEX Inc., Alameda, CA. www.sybex.com Glossary of Networking Terms 581 backbone ISP An ISP with very high-speed connections (several hundred megabits per second) to the other backbone ISPs. These connections form the “backbone” of the Internet . backup domain controller (BDC) Computer on a Windows NT network that has a read-only copy of the SAM database for fault-tolerance and per- formance-enhancement purposes. See also Security Accounts Manager. bandwidth In network communications, the amount of data that can be sent across a wire in a given time (usually in one second). Each communica- tion that passes along the wire decreases the amount of available bandwidth. banner ads A rectangular graphic, generally about 500 pixels wide by 60 pixels tall, that’s placed on a Web page, usually to sell some items or services. When a surfer clicks a banner ad, he’s taken to the advertiser’s Web site (and usually, the fact that he got there through a banner ad is noted). baseband A transmission technique in which the signal uses the entire bandwidth of a transmission medium. baseline A category of network documentation that indicates how the net- work normally runs. It includes such information as network statistics, server utilization trends, and processor performance statistics. Bearer channel The channels in an ISDN line that carry data (also called the B channel). Each Bearer channel typically has a bandwidth of 64Kbps. bindery Flat database used in NetWare 3. x and earlier servers to store net- work resource information (such as user, group, and security information). Each server in the network has its own bindery database. BinHex The MacOS file compression standard. The BinHex format allows you to combine several files into one compressed unit and extract them indi- vidually. They usually have an .HQX filename extension. biometric authentication A type of authentication that uses fingerprints, retinal scan, voiceprints, face recognition, and other biologically unique fea- tures of humans instead of passwords for network authentication. Bit Fiddler A virus that changes small random bits in files. Copyright © 2000 SYBEX Inc., Alameda, CA. www.sybex.com 582 Glossary of Networking Terms BNC connector Tubular connectors most commonly used with coaxial cable. boot sector virus A virus that overrides the boot sector, thereby making it appear as if there is no pointer to your operating system. When this happens, you will see a “Missing operating system” or “Hard disk not found” error message on power-up. bounded medium A network medium where the signal travels over a cable of some kind. bridge A network device, operating at the Data Link layer, that logically separates a single network into segments but lets the two segments appear to be one network to higher-layer protocols. broadband A network transmission method in which a single transmis- sion medium is divided so that multiple signals can travel across the same medium simultaneously. brouter A connectivity device that will act as a router for routable proto- cols and act as a bridge for nonroutable protocols. brownout See power brownout. browser A computer program that uses the Hypertext Transfer Protocol and is used on a workstation to access hosts on the Web. brute force attack A type of network attack where the attacker simply uses a computer to generate random combinations of characters in the hope of stumbling onto the correct combination for a password. Brute force attacks rely on the capacity of attacking computers to tirelessly generate dif- ferent combinations of characters and feed them to defended network resources. burst mode An addition to NCP that allows multiple date frames to be sent without waiting for an acknowledgment for the previous frame of data. See also NetWare Core Protocol. business-to-business commerce Businesses providing goods and ser- vices to other businesses. Copyright © 2000 SYBEX Inc., Alameda, CA. www.sybex.com Glossary of Networking Terms 583 bytecodes The result of running Java source code through a Java com- piler. This result is used within an imaginary chip called the Java Virtual Machine (JVM). See also Java Virtual Machine (JVM). C A general-purpose programming language that can be used to write pro- grams for various platforms. The code must be specifically written for a par- ticular platform, however. C++ An object-oriented version of C. See also C. CA See certification authority. cable A physical transmission medium that has a central conductor of wire or fiber surrounded by a plastic jacket. cable map A general network documentation indicating each cable’s source and destination as well as where each network cable runs. cable tester See time-domain reflectometer. cache-in-a-box A “black box” that you plug into your network to increase Internet surfing by caching portions of frequently accessed Web sites. CAD program Any program that is used during the computer-aided design (CAD) process; typically used by engineers. captive audience policy A type of Web content policy that by which Web site creators create the content in the format they want, their audience must use only browsers that work with these content types. Captive audience pol- icies usually rely on the content creators also having control of the browsers people have on their desktops. carrier sense multiple access with collision avoidance (CSMA/CA) A media access method that sends a request to send (RTS) packet and waits to receive a clear to send (CTS) packet before sending. Once the CTS is received, the sender sends the packet of information. carrier sense multiple access with collision detection (CSMA/CD) A media access method that senses whether there is a signal on the wire, indi- cating that someone is transmitting currently. If no one else is transmitting, it attempts a transmission and listens to hear whether someone else tries to transmit at the same time. If this happens, both senders back off and don’t transmit again until some random period of time has passed. Copyright © 2000 SYBEX Inc., Alameda, CA. www.sybex.com 584 Glossary of Networking Terms centralized WAN A WAN with a computer that connects computers and dumb terminals to a central site. See also wide area network. certificate Proof that someone (or something) is what he or she (or it) claims to be. certification authority An organization that’s responsible for verifying the identity of people and issuing certificates to those whose identities can be verified. Also known as a certificate authority. CGI See Common Gateway Interface. ciphertext Text after it has been encrypted. CIR See Committed Information Rate. cleartext Normal text before it is encrypted. Client Services for NetWare (CSNW) Software that allows Windows NT computers to access NetWare resources. client-server network A server-centric network in which all resources are stored on a file server; processing power is distributed among workstations and the file server. client-side markup language Any system of adding tags (markup) to a text document in order to supply information about how the text should be rendered in a Web browser or what it means. Client-side markup languages are interpreted by Web browsers. clipper chip A hardware implementation of the skipjack encryption algorithm. coaxial cable Often referred to as coax. A type of cable used in network wiring. Typical coaxial cable types include RG-58 and RG-62. 10Base-2 Ethernet networks use coaxial cable. Coaxial cable is usually shielded. cold site backup system A backup system that does not run continu- ously. Therefore, before you can restore data, the computer must be repaired and the software must be reloaded on the server. Copyright © 2000 SYBEX Inc., Alameda, CA. www.sybex.com Glossary of Networking Terms 585 collision The error condition that occurs when two stations on a CSMA/ CD network transmit data (at the Data link layer) at the same time. See also carrier sense multiple access with collision detection. Committed Information Rate (CIR) A commitment from your service provider stating the minimum bandwidth you will get on a Frame Relay network. Common Gateway Interface (CGI) A specification that defines a way of packaging text data (such as the contents of a form) for transmission over a network. The CGI specification takes the contents of a form and the names of the form elements (as specified in HTML) and assembles them all into a long string of characters. That string can then be passed to a program on the server side for processing and a response. compiler A special software program that translates the human-readable source code of a programming language into machine code that processors and operating systems can understand. Compilers are usually specific to a programming language. Component Object Model (COM) The Microsoft “twin” to JavaBeans. It’s a means of writing independent code modules and having them commu- nicate with one another. The idea is that you could have a single, specialized COM module that various other pieces of software (other COM modules and non-COM programs) refer to for different reasons. Unlike JavaBeans, however, COM currently will work only on Windows (and some Unix) machines. concentrator See hub. connectionless protocol A transport protocol, such as UDP, that does not create a virtual connection between sending and receiving stations. See also User Datagram Protocol. connection-oriented protocol A transport protocol that uses acknowl- edgments and responses to establish a virtual connection between sending and receiving stations. TCP is a connection-oriented protocol. See also Transmission Control Protocol. Copyright © 2000 SYBEX Inc., Alameda, CA. www.sybex.com 586 Glossary of Networking Terms CONSOLE.LOG A NetWare server log file that keeps a history of all errors and information that has been displayed on the server’s console since the CONLOG.NLM file was loaded. contention A media access method that allows any computer to transmit whenever it has data. Every station has an equal opportunity to transmit. cookie A special text message given to a Web browser by a Web server. The browser stores this message on the local hard disk. The next time someone using that Web browser on that computer visits the same Web server, the Web browser sends this message back to the Web server (which created it). Cookies are used to provide customized Web sites for users. copyleft A legal term whereby an organization (usually a not-for-profit group like the Free Software Foundation) establishes copyright to an item of intellectual property—source code for software, usually—then distributes it free of charge. People who use the software must agree to its licensing agree- ment, which specifies that they may not make a profit on its distribution. The GNU utilities are covered by copyleft. copyright The right of an author, artist, publisher, or other legal entity to collect money from the use of words, music, performance works, items of visual art, or other creative products. country codes The two-letter abbreviations for countries; used in the DNS hierarchy. See also Domain Name Services. CRC See cyclical redundancy check. crossover cable The troubleshooting tool used in Ethernet UTP installa- tions to test communications between two stations, bypassing the hub. See also unshielded-twisted pair. cross-sell The process of selling the buyer of a given product accessories and other related products. CSMA/CA See carrier sense multiple access with collision avoidance. CSMA/CD See carrier sense multiple access with collision detection. CSNW See Client Services for NetWare. Copyright © 2000 SYBEX Inc., Alameda, CA. www.sybex.com [...]... databases and responding to queries sent to them This definition also refers to a type of server that runs database server software datagram A unit of data smaller than a packet Copyright © 2000 SYBEX Inc., Alameda, CA www.sybex.com 588 Glossary of Networking Terms Dataphone Digital Service (DDS) line This type of Internet bandwidth link technology from AT&T is a dedicated, point-to-point connection... Protocol See Institute of Electrical and Electronics Engineers IEEE 802.x standards The IEEE standards for LAN and MAN networking Copyright © 2000 SYBEX Inc., Alameda, CA www.sybex.com Glossary of Networking Terms 599 IEEE 802.1 LAN/MAN Management Standard that specifies LAN/MAN network management and internetworking IEEE 802.2 Logical Link Control Standard that specifies the operation of the Logical Link... platform that has a Java Virtual Machine installed (which is 95 percent of the operating systems that exist) Java servlets Special Java programs that run on a Web server and expand the capabilities of the Web server software Copyright © 2000 SYBEX Inc., Alameda, CA www.sybex.com Glossary of Networking Terms 603 Java Virtual Machine (JVM) Software developed by Sun Microsystems that creates a virtual Java... Alameda, CA www.sybex.com 594 Glossary of Networking Terms Event Notification Services (ENS) A component of Novell Directory Print Services (NDPS) broker that notifies users and administrators of network-printing events See also Novell Directory Print Services expansion slot A slot on the computer’s bus Expansion cards are plugged into these slots to expand the functionality of the computer (for example,... tolerance Copyright © 2000 SYBEX Inc., Alameda, CA www.sybex.com Glossary of Networking Terms 595 fiber-optic A type of network cable that uses a central glass or plastic core surrounded by a plastic coating fibre channel A type of server-to-storage system connection that uses fiber-optic connectors File and Print Services for NetWare (FPNW) A method of providing files and printers hosted by Windows NT to Novell... www.sybex.com Glossary of Networking Terms digital certificate Internet 589 Digital proof that someone is who he claims to be on the digital signature Pieces of electronic information that serve to guarantee that an item—a document, a credit card number, whatever—was not tampered with as it traveled over the Internet from sender to recipient By examining a digital signature that arrives with a piece of data,... Protocol/Internet Protocol drive mapping The process of assigning a drive letter at the client to a directory or folder on the server DSL See Digital Subscriber Line Copyright © 2000 SYBEX Inc., Alameda, CA www.sybex.com Glossary of Networking Terms 591 D-type connector A type of network connector that connects computer peripherals It contains rows of pins or sockets shaped in a sideways D dumb terminal... access control A script of commands that can be invoked with a single keystroke mail bombing See mail flooding Copyright © 2000 SYBEX Inc., Alameda, CA www.sybex.com Glossary of Networking Terms 607 mail flooding Unleashing a barrage of mail on a particular user in an attempt to render the user’s e-mail account useless This is typically done by signing the user up for hundreds of e-mail mailing lists... network that encompasses an Microsoft Word A popular word processing application created by Microsoft Corporation It exists in Windows and MacOS versions Word files usually carry DOC filename extensions Copyright © 2000 SYBEX Inc., Alameda, CA www.sybex.com 608 Glossary of Networking Terms mirrored hard drive Two drives to which the same information is written Therefore, if one of the drives fails, the information... emergency arises.) If a server fails, another just takes over without any interruption of service multiplexing The process of dividing a single network medium into multiple channels Copyright © 2000 SYBEX Inc., Alameda, CA www.sybex.com Glossary of Networking Terms 609 Multipurpose Internet Mail Extension (MIME) A feature of both e-mail and Web clients that allows nonstandard file types to be opened by . Glossary of Networking Terms Copyright © 2000 SYBEX Inc., Alameda, CA. www.sybex.com 578 Glossary of Networking Terms 10Base-2 . CA. www.sybex.com Glossary of Networking Terms 589 digital certificate Digital proof that someone is who he claims to be on the Internet. digital signature Pieces of