Network Plus 2005 In Depth

792 Glossary

loopback plug—A connector used for troubleshooting that plugs into a port (for example, a serial, parallel, or RJ-45 port) and crosses over the transmit line to the receive line, allowing outgoing signals to be redirected back into the computer for testing.

loopback test—An attempt to contact one’s own machine for troubleshooting purposes. In TCP/IPbased networking, a loopback test can be performed by communicating with an IP address that begins with an octet of 127. Usually, this means pinging the address 127.0.0.1.

LOS (line-of-sight)—A wireless signal or path that travels directly in a straight line from its transmitter to its intended receiver. This type of propagation uses the least amount of energy and results in the reception of the clearest possible signal.

low earth orbiting—See LEO.

lpd (line printer daemon)—A UNIX service responsible for printing files placed in the printer queue by the lpr command.

lpr—The UNIX command. This command simply places files in the printer queue. The files are subsequently printed with lpd, the print service.

MAC (Media Access Control) sublayer—The lower sublayer of the Data Link layer. The MAC appends the physical address of the destination computer onto the frame.

MAC address—A 12-character string that uniquely identifies a network node. The manufacturer hardcodes the MAC address into the NIC. This address is composed of the Block ID and Device ID.

Mac OS X Server—A proprietary network operating system from Apple Computer that is based on a version of UNIX.

Mach—A UNIX-type of operating system kernel developed by researchers at Carnegie Mellon University in Pittsburgh, PA. Mach is the basis for the kernel in Mac OS X Server.

macro virus—A virus that takes the form of an application (for example, a word-processing or spreadsheet) program macro, which may execute when the program is in use.

mail server—A server that manages the storage and transfer of e-mail messages.

mail services—The network services that manage the storage and transfer of e-mail between users on a network. In addition to sending, receiving, and storing mail, mail services can include filtering, routing, notification, scheduling, and data exchange with other mail servers.

main bus—See bus.

MAN (metropolitan area network)—A network that is larger than a LAN, typically connecting clients and servers from multiple buildings, but within a limited geographic area. For example, a MAN could connect multiple city government buildings around a city’s center.

man pages—See manual pages.

managed hub—See intelligent hub.

Management Information Base—See MIB.

management services—The network services that centrally administer and simplify complicated management tasks on the network. Examples of management services include license tracking, security auditing, asset management, address management, software distribution, traffic monitoring, load balancing, and hardware diagnosis.

Glossary 793

manual pages—The online documentation for any variety of the UNIX operating system. This documentation describes the use of the commands and the programming interface.

map—The action of associating a disk, directory, or device with a drive letter.

MAU (Multistation Access Unit)—A device on a Token Ring network that regenerates signals; equivalent to a hub.

maximum transmission unit—See MTU.

MCSE (Microsoft Certified Systems Engineer)—A professional certification established by Microsoft that demonstrates in-depth knowledge about Microsoft products, including Windows 2000, Windows XP, and Windows Server 2003.

Mechanical Transfer Registered Jack—See MT-RJ.

Media Access Control sublayer—See MAC (Media Access Control) sublayer.

media converter—A device that enables networks or segments using different media to interconnect and exchange signals.

medium earth orbiting–See MEO.

member server—A type of server on a Windows Server 2003 network that does not hold directory information and therefore cannot authenticate users.

memory range—A hexadecimal number that indicates the area of memory that the NIC and CPU will use for exchanging, or buffering, data. As with IRQs, some memory ranges are reserved for specific devices—most notably, the motherboard.

MEO (medium earth orbiting)—A type of satellite that orbits the earth 10,390 kilometers above its surface, positioned between the equator and the poles. MEO satellites can cover a larger area of the earth’s surface than LEO satellites while using less power and causing less signal delay than GEO satellites.

mesh topology WAN—A type of WAN in which several sites are directly interconnected. Mesh WANs are highly fault-tolerant because they provide multiple routes for data to follow between any two points.

message switching—A type of switching in which a connection is established between two devices in the connection path; one device transfers data to the second device, then breaks the connection. The information is stored and forwarded from the second device after a connection between that device and a third device on the path is established.

Metaframe—A software package from Citrix Systems, Inc. that supplies terminal services to remote clients.

metropolitan area network—See MAN.

MIB (Management Information Base)—A database used in network management that contains a device’s definitions of managed objects and their data.

Microsoft Certified Systems Engineer—See MCSE.

Microsoft Challenge Handshake Authentication Protocol—See MS-CHAP.

Microsoft Challenge Handshake Authentication Protocol, version 2—See MS-CHAPv2.

Microsoft Directory Synchronization Services—See MSDSS.

794 Glossary

Microsoft Management Console—See MMC.

Microsoft Windows Services for NetWare—A suite of tools for integrating Windows 2000 Server or Windows Server 2003 servers with NetWare servers. The suite includes a tool for synchronizing data from NetWare directories with Active Directory, a tool for migrating files from a NetWare server to a Windows Server 2003 server, and File and Print Services for NetWare, which allows a Windows Server 2003 computer to appear as a NetWare server to NetWare clients.

middleware—The software that sits between the client and server in a 3-tier architecture. Middleware may be used as a messaging service between clients and servers, as a universal query language for databases, or as means of coordinating processes between multiple servers that need to work together in servicing clients.

milestone—A reference point that marks the completion of a major task or group of tasks in a project and contributes to measuring the project’s progress.

MIME (Multipurpose Internet Mail Extensions)—A standard for encoding and interpreting binary files, images, video, and non-ASCII character sets within an e-mail message.

mirroring—A fault-tolerance technique in which one component or device duplicates the activity of another.

MMC (Microsoft Management Console)—A customizable, graphical network management interface used with Windows Server 2003.

MMF (multimode fiber)—A type of fiber-optic cable that contains a core with a diameter between 50 and 100 microns, through which many pulses of light generated by a light-_emitting diode (LED) travel at different angles.

mobile—A type of wireless system in which the receiver can be located anywhere within the transmitter’s range. This allows the receiver to roam from one place to another while continuing to pick up its signal.

modal bandwidth—A measure of the highest frequency of signal a multimode fiber-optic cable can support over a specific distance. Modal bandwidth is measured in MHz-km.

modem—A device that modulates analog signals into digital signals at the transmitting end for transmission over telephone lines, and demodulates digital signals into analog signals at the receiving end.

modular router—A router with multiple slots that can hold different interface cards or other devices so as to provide flexible, customizable network interoperability.

modulation—A technique for formatting signals in which one property of a simple carrier wave is modified by the addition of a data signal during transmission.

Monitor—A NetWare NLM that provides a text-based menu for viewing and modifying server parameters, such as protocols, bindings, system resources, and loaded modules.

motherboard—The main circuit board that controls a computer.

mount—The process of making a disk partition available.

MRTG (Multi Router Traffic Grapher)—A command-line utility that uses SNMP to poll devices, collects data in a log file, and then generates HTML-based views of the data. MRTG is freely distributed software originally written by Tobias Oetiker, a networking professional who in the early 1990s saw a need for a tool to regularly measure the status of his organization’s WAN link.

Glossary 795

MS-CHAP (Microsoft Challenge Handshake Authentication Protocol)—An authentication protocol offered by Microsoft with its Windows clients and servers. Similar to CHAP, MS-CHAP uses a threeway handshake to verify a client’s credentials and encrypts passwords with a challenge text.

MS-CHAPv2 (Microsoft Challenge Authentication Protocol, version 2)—An authentication protocol provided with Windows XP, 2000, and Server 2003 operating systems that follows the CHAP model, but uses stronger encryption, uses different encryption keys for transmission and reception, and requires mutual authentication between two computers.

MSDSS (Microsoft Directory Synchronization Services)—An application that, when installed on a Windows Server 2003 server, can synchronize information between an Active Directory database and a NetWare eDirectory database.

MT-RJ (Mechanical Transfer Registered Jack)—A connector used with single-mode or multimode fiber-optic cable.

MTU (maximum transmission unit)—The largest data unit a network (for example, Ethernet or Token Ring) will accept for transmission.

Multi Router Traffic Grapher—See MRTG.

multicast address—A type of address in the IPv6 that represents multiple interfaces, often on multiple nodes. An IPv6 multicast address begins with the following hexadecimal field: FF0x, where x is a character that identifies the address’s group scope.

multicasting—A means of transmission in which one device sends data to a specific group of devices (not necessarily the entire network segment) in a point-to-multipoint fashion. Multicasting can be used for videoconferencing over the Internet, for example.

multimeter—A simple instrument that can measure multiple characteristics of an electric circuit, including its resistance and voltage.

multimode fiber—See MMF.—

multipath—The characteristic of wireless signals that follow a number of different paths to their destination (for example, because of reflection, diffraction, and scattering).

multiplexer (mux)—A device that separates a medium into multiple channels and issues signals to each of those subchannels.

multiplexing—A form of transmission that allows multiple signals to travel simultaneously over one medium.

multiprocessing—The technique of splitting tasks among multiple processors to expedite the completion of any single instruction.

multiprotocol network—A network that uses more than one protocol.

Multipurpose Internet Mail Extensions—See MIME.

Multistation Access Unit—See MAU.

multitasking—The ability of a processor to perform multiple activities in a brief period of time (often seeming simultaneous to the user).

mutual authentication—An authentication scheme in which both computers verify the credentials of each other.

796 Glossary

name server—A server that contains a database of TCP/IP host names and their associated IP addresses. A name server supplies a resolver with the requested information. If it cannot resolve the IP address, the query passes to a higher-level name server.

namespace—The complete database of hierarchical names (including host and domain names) used to resolve IP addresses with their hosts.

narrowband—A type of wireless transmission in which signals travel over a single frequency or within a specified frequency range.

NAS (network attached storage)—A device or set of devices attached to a client/server network, dedicated to providing highly fault-tolerant access to large quantities of data. NAS depends on traditional network transmission methods such as Ethernet.

NAT (Network Address Translation)—A technique in which IP addresses used on a private network are assigned a public IP address by a gateway when accessing a public network.

nbtstat—A TCP/IP troubleshooting utility that provides information about NetBIOS names and their addresses. If you know the NetBIOS name of a workstation, you can use nbtstat to determine its IP address.

NDS (NetWare Directory Services)—In NetWare 4.x and 5.x, the system of managing multiple servers and their resources, including users, volumes, groups, profiles, and printers, used with NetWare versions 4.x and 5.x. The NDS model was the precursor to eDirectory.

needs assessment—The process of clarifying the reasons and objectives for a proposed change to determine whether the change is worthwhile and necessary, and to elucidate the scope and nature of the proposed change.

negative frame sequence check—The result of the CRC (cyclic redundancy check) generated by the originating node not matching the checksum calculated from the data received. It usually indicates noise or transmission problems on the LAN interface or cabling. A high number of (nonmatching) CRCs usually results from excessive collisions or a station transmitting bad data.

net mask—See subnet mask.

NetBEUI (NetBIOS Enhanced User Interface)—The Microsoft adaptation of the IBM NetBIOS protocol. NetBEUI expands on NetBIOS by adding a Transport layer component. NetBEUI is a fast and efficient protocol that consumes few network resources, provides excellent error correction, and requires little configuration.

NetBIOS (Network Basic Input Output System)—A protocol designed by IBM to provide Transport and Session layer services for applications running on small, homogeneous networks.

NetBIOS Enhanced User Interface—See NetBEUI.

NetDrive—The client software that enables Windows workstations to connect to a NetWare 6.5 server using standard Internet protocols, such as FTP and HTTP. After connecting through NetDrive, a user can navigate the server’s directories and manage files as if navigating a Windows hard disk.

NETMON—Novell’s network monitoring NLM. NETMON is included in NetWare 5.x and 6.x.

Glossary 797

netstat—A TCP/IP troubleshooting utility that displays statistics and the state of current TCP/IP connections. It also displays ports, which can signal whether services are using the correct ports.

NetStorage—A TCP/IP-based tool from Novell that allows users to navigate directories and manage files on a NetWare 6.x server.

NetWare 3.x—The group of NetWare versions that includes versions 3.0, 3.1, and 3.2.

NetWare 4.x—The group of NetWare versions that includes versions 4.0, 4.1, and 4.11.

NetWare 5.x—The group of NetWare versions that includes versions 5.0, 5.1, and 5.11.

NetWare 6.x—The group of NetWare versions that includes versions 6.0 and 6.5.

NetWare Directory Services—See NDS.

NetWare Integrated Kernel—The core of NetWare 6.x’s operating system. The NetWare Integrated Kernel manages multiprocessing, multithreading, and access to the server’s interrupts, memory, and I/O address space.

NetWare loadable module—See NLM.

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

network access method—See access method.

network adapter—See NIC.

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

Network Address Translation—See NAT.

network analyzer—See protocol analyzer.

network attached storage—See NAS.

Network Basic Input Output System—See NetBIOS.

network class—A classification for TCP/IP-based networks that pertains to the network’s potential size and is indicated by an IP address’s network ID and subnet mask. Network classes A, B, and C are commonly used by clients on LANs; network classes D and E are reserved for special purposes.

Network File System—See NFS.

network ID—The portion of an IP address common to all nodes on the same network or subnet.

network interface card—See NIC.

network key—A key (or character string) required for a wireless station to associate with an access point using WEP.

Network layer—The third layer in the OSI Model. Protocols in the Network layer translate network addresses into their physical counterparts and decide how to route data from the sender to the receiver.

Network layer address—See network address.

798 Glossary

network management—The assessment, monitoring, and maintenance of the devices and connections on a network.

Network Monitor—A network monitoring program that comes with Windows Server 2003 (as well as with Windows NT and Windows 2000 Server).

network monitor—A software-based tool that monitors traffic on the network from a server or workstation attached to the network. Network monitors typically can interpret up to Layer 3 of the OSI Model.

Network News Transport Protocol—See NNTP. network number—See network ID.

network operating system—See NOS. network prefix—See network ID. network service provider—See NSP.

network services—The functions provided by a network.

Network Termination 1—See NT1.

Network Termination 2—See NT2.

Network Time Protocol—See NTP.

network virus—A virus that takes advantage of network protocols, commands, messaging programs, and data links to propagate itself. Although all viruses could theoretically travel across network connections, network viruses are specially designed to attack network vulnerabilities.

Network+ (Net+)—The professional certification established by CompTIA that verifies broad, vendorindependent networking technology skills such as an understanding of protocols, topologies, networking hardware, and network troubleshooting.

New Technology File System—See NTFS.

newsgroup—An Internet-based forum for exchanging messages on a particular topic. Newsgroups rely on NNTP for the collection and dissemination of messages.

NFS (Network File System)—A popular remote file system created by Sun Microsystems, and available for UNIX-type of systems.

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

NLM (NetWare loadable module)—A routine associated with a particular NetWare application or service. Each NLM consumes some of the server’s memory and processor resources (at least temporarily). The kernel requires many NLMs to run NetWare’s core operating system.

NNTP (Network News Transport Protocol)—An Application layer protocol in the TCP/IP suite which facilitates the exchange of newsgroup messages, or articles, between multiple servers and users.

node—A computer or other device connected to a network, which has a unique address and is capable of sending or receiving data.

Glossary 799

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

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

Novell Storage Services—See NSS.

nslookup—A TCP/IP utility that allows you to look up the DNS host name of a network node by specifying its IP address, or vice versa. This ability is useful for verifying that a host is configured correctly and for troubleshooting DNS resolution problems.

NSP (network service provider)—A carrier that provides long-distance (and often global) connectivity between major data-switching centers across the Internet. AT&T, PSINet, Sprintlink, and UUNET (MCI Worldcom) are all examples of network service providers. Customers, including ISPs, can lease dedicated private or public Internet connections from an NSP.

NSS (Novell Storage Services)—The 64-bit file access and storage system installed by default and preferred for use on NetWare 6.x servers. NSS offers several benefits over traditional file systems such as FAT, including faster access, more efficient use of memory, support for files or directories as large as 8 TB, and up to a trillion files in a single directory.

NT1 (Network Termination 1)—A device used on ISDN networks that connects the incoming twistedpair wiring with the customer’s ISDN terminal equipment.

NT2 (Network Termination 2)—An additional connection device required on PRI to handle the multiple ISDN lines between the customer’s network termination connection and the local phone company’s wires.

Nterprise Linux Services—A group of tools and programs for integrating Linux computers into a NetWare 6.5 network. Nterprise Linux Services consists of client tools for accessing eDirectory, development tools for use with DirXML, plus browser-based file and print services.

NTFS (New Technology File System)—A file system developed by Microsoft for use with its Windows NT, Windows 2000 Server, and Windows Server 2003 operating systems. NTFS integrates reliability, compression, the ability to handle massive files, system security, and fast access. Most Windows Server 2003 partitions employ NTFS.

NTP (Network Time Protocol)—A simple Application layer protocol in the TCP/IP suite used to synchronize the clocks of computers on a network. NTP depends on UDP for Transport layer services.

object—A representation of a thing or person associated with the network that belongs in the NOS directory. Objects include users, printers, groups, computers, data files, and applications.

object class—See class.

OC (Optical Carrier)—An internationally recognized rating that indicates throughput rates for SONET connections.

octet—One of the four 8-bit bytes that are separated by periods and together make up an IP address.

offline UPS—See standby UPS.

800 Glossary

ohmmeter—A device used to measure resistance in an electrical circuit.

omnidirectional antenna—A type of antenna that issues and receives wireless signals with equal strength and clarity in all directions. This type of antenna is used when many different receivers must be able to pick up the signal, or when the receiver’s location is highly mobile.

on-board NIC—A NIC that is integrated into a computer’s motherboard, rather than connected via an expansion slot or peripheral bus.

on-board port—A port that is integrated into a computer’s motherboard.

online backup—A technique in which data is backed up to a central location over the Internet.

online UPS—A power supply that uses the A/C power from the wall outlet to continuously charge its battery, while providing power to a network device through its battery.

Open Directory—The version of OpenLDAP by Apple Computer that is included with Mac OS X Server.

Open Shortest Path First—See OSPF.

open source software—The term used to describe software that is distributed with few restrictions and whose source code is freely available.

Open Systems Interconnection Model—See OSI (Open Systems Interconnection) Model.

OpenLDAP—A popular open source application included with many Linux distributions that implements LDAP.

OpenSSH—An open source version of the SSH suite of protocols.

Optical Carrier—See OC.

optical loss—The degradation of a light signal on a fiber-optic network.

optical media—A type of media capable of storing digitized data, which uses a laser to write data to it and read data from it.

optical time domain reflectometer—See OTDR.

organizational unit—See OU.

OSI (Open Systems Interconnection) Model—A model for understanding and developing computer- to-computer communication developed in the 1980s by ISO. It divides networking functions among seven layers: Physical, Data Link, Network, Transport, Session, Presentation, and Application.

OSPF (Open Shortest Path First)—A routing protocol that makes up for some of the limitations of RIP and can coexist with RIP on a network.

OTDR (optical time domain reflectometer)—A performance testing device for use with fiber-optic networks. An OTDR works by issuing a light-based signal on a fiber-optic cable and measuring the way in which the signal bounces back (or reflects) to the OTDR. By measuring the length of time it takes the signal to return, an OTDR can determine the location of a fault.

OU (organizational unit)—A logical receptacle for holding objects with similar characteristics or privileges in an NOS directory. Containers form the branches of the directory tree.

Glossary 801

overhead—The nondata information that must accompany data in order for a signal to be properly routed and interpreted by the network.

P2P network—See peer-to-peer network.

Packet Internet Groper—See PING.

packet switching—A type of switching in which data is broken into packets before it is transported. In packet switching, packets can travel any path on the network to their destination, because each packet contains a destination address and sequencing information.

packet-filtering firewall—A router that operates at the Data Link and Transport layers of the OSI Model, examining the header of every packet of data that it receives to determine whether that type of packet is authorized to continue to its destination. Packet-filtering firewalls are also called screening firewalls.

padding—The bytes added to the data (or information) portion of an Ethernet frame to ensure this field is at least 46 bytes in size. Padding has no effect on the data carried by the frame.

page file—A file on the hard disk that is used for virtual memory.

paging—The process of moving blocks of information, called pages, between RAM and into a page file on disk.

paging file—See page file.

PAN (personal area network)—A small (usually home) network composed of personal communications devices.

PAP (Password Authentication Protocol)—A simple authentication protocol that operates over PPP. Using PAP, a client issues its credentials in a request to authenticate, and the server responds with a confirmation or denial of authentication after comparing the credentials to those in its database. PAP is not very secure and is therefore rarely used on modern networks.

parallel backbone—A type of backbone that consists of more than one connection from the central router or switch to each network segment.

parity—The mechanism used to verify the integrity of data by making the number of bits in a byte sum equal to either an odd or even number.

parity error checking—The process of comparing the parity of data read from a disk with the type of parity used by the system.

partial mesh WAN—A version of a mesh topology WAN in which only critical sites are directly interconnected and secondary sites are connected through star or ring topologies. Partial mesh WANs are less expensive to implement than full mesh WANs.

partition—An area of a computer’s hard disk that is logically defined and acts as a separate disk drive.

passive hub—A hub that simply retransmits signals over the network.

passive scanning—In the context of wireless networking, the process in which a station listens to several channels within a frequency range for a beacon issued by an access point.

Password Authentication Protocol—See PAP.