R Reference Point

Used with ISDN networks to identify the connection between an NT1 and an S/T device. The S/T device converts the 4-wire network to the two-wire ISDN standard network.

Radio Frequency Interference (RFI)

Noise created in the radio-frequency range.

RADIUS Server

See Remote Authentication Dial-In User Service Server.

RAID

See Redundant Array of Inexpensive Disks.

RAID 0

RAID 0 writes data across multiple hard-disk partitions in what is called a stripe set. This can greatly improve speed as multiple hard disks are working at the same time. RAID 0 can be implemented through the use of Windows software or on third-party hardware.

RAID 1

RAID 1 uses disk mirroring, which writes information to disk twice – once to the primary file, and once to the mirror.

RAID 5

RAID 5 (striped with parity) writes data to hard disk in stripe sets. Parity checksums will be written across all disks in the stripe set; they can be used to recreate information lost if a single disk in the stripe set fails.

RAID 5 Volume

A volume set that stripes the data over multiple disk channels. RAID 5 volumes place a parity stripe across the volume. RAID 5 volumes are fault tolerant.

RAID 10

RAID 10 (sometimes referred to as RAID 1 + 0) implements striping as in RAID 1 and then mirrors the stripe sets.

RAID Controllers

Hard disk drive controllers that implement RAID in hardware. See also Redundant Array of Inexpensive Disks.

RAM

See Random Access Memory.

Random Access Memory (RAM)

Integrated circuits that store digital bits in massive arrays of logical gates or capacitors. RAM is the primary memory store for modern computers, storing all running software processes and contextual data. See also Microprocessor.

RARP

See Reverse Address Resolution Protocol.

RAS

See Remote Access Service.

Rate Queue

A value, assigned to one or more virtual circuits, that specifies the speed at which an individual virtual circuit will transmit data to the remote end. Every rate queue identifies a segment of the total bandwidth available on an ATM link. The sum of all rate queues should not exceed the total available bandwidth.

Raw Mode

A specific operational mode of Microsoft Exchange Administrator that allows the viewing and manipulating of all the properties of Exchange objects. Can be initiated by running ADMIN /raw.

RCP

See Remote Copy Protocol.

RD

Removes a directory.

RDP

See Remote Desktop Protocol.

Read-Ahead

A SQL Server mechanism for retrieving data from disk into cache before the data is actually needed. Separate read-ahead threads pull the data into the cache, thus freeing the query thread to process the data that it finds in cache.

READPIPE

A command-line utility that can be used in conjunction with the MAKEPIPE utility to verify that the Named Pipes protocol is working properly.

Real Mode

The normal operating mode of PCs, in which only the first 1 MB of memory can be addressed.

Real-Time Application

A process that must respond to external events at least as fast as those events can occur. Real-time threads must run at very high priorities to ensure their ability to respond in real time. See also Process.

Real-Time Scanner

An anti-virus software application that operates as a background task, allowing the computer to continue working at normal speed, with no perceptible slowing. See also On-Access Scanner.

Recipient

An Exchange object that can receive a message. Recipients objects include mailboxes, distribution lists, public folders, and custom recipients.

Recipient Update Service (RUS)

This is part of the Exchange System Attendant and is responsible for keeping Address Lists up-to-date and creating proxy addresses for users.

Recovery Agent

Users that have recovery authority. These users can recover encrypted files when the original key material is unavailable. See also Recovery Key.

Recovery Console

A Windows option for recovering from a failed system. The Recovery Console starts Windows without the graphical interface and allows the administrator limited capabilities, such as adding or replacing files and enabling and disabling services.

Recovery Key

A key that allows encrypted data to be unencrypted without the original key.

Recovery Server

A server configured to be used in place of another server. If a server goes down because of a failure or is taken down for maintenance, a recovery server can be brought online to provide continued service to users. See also Standby Server.

Recursion

The process by which DNS servers or clients use other DNS servers to resolve DNS names to TCP/IP address queries.

Recycle Bin

A folder that holds files and folders that have been deleted. Files can be retrieved or cleared (for permanent deletion) from the Recycle Bin.

Redirect

The action used by some viruses to point a command to a different location. Often this different location is the address of the virus and not the original file or application.

Redirector

Software loaded onto a workstation that can forward or redirect requests away from the local bus of the computer onto a network. These requests are then handled by a server. This type of software is often called a shell, requester, or client. See also Client Services for NetWare and File System.

Redirector Service

A service that provides connectivity to a server service.

Redistribution

Command used in Cisco routers to inject the paths found from one type of routing protocol into another type of routing protocol. For example, networks found by RIP can be inserted into an IGRP network.

Reduced Instruction Set Computer (RISC)

A microprocessor technology that implements fewer and more primitive instructions than typical microprocessors and can therefore be implemented quickly with the most modern semiconductor technology and speeds. Programs written for RISC microprocessors require more instructions (longer programs) to perform the same task as a normal microprocessor but are capable of a greater degree of optimization and therefore usually run faster. See also Microprocessor.

Redundancy

In internetworking, the duplication of connections, devices, or services that can be used as a backup in the event that the primary connections, devices, or services fail.

Redundant Arrays of Inexpensive Disks (RAID)

A technique for achieving fault tolerance on a network by using several hard disks. If one or more drives fail, network data can be saved.

REGEDIT

A Windows program used to edit the Registry. It does not support full editing, as does the REGEDT32 program, but it has better search capabilities than REGEDT32. See also Registry.

REGEDT32

The primary utility for editing the Windows Registry. See also Registry.

Regional Model

A business model with well-defined geographic boundaries, a simple infrastructure, and no complex setup issues.

Regional Options

A Control Panel utility used to enable and configure multilingual editing and viewing on a localized version of Windows.

Register Jack Connector

Is used with twisted-pair wiring to connect the copper wire to network interface cards, switches, and hubs.

Registry

A database of settings required and maintained by Windows and its components. The Registry stores Control Panel settings. You can use the Registry Editor to change these settings.

Relational Database

A database composed of tables that contain related data and other objects, such as views, stored procedures, rules, and defaults. Also, a database of related information that supports the SQL query language. SQL Server databases are stored on database devices.

Relational Database Management System (RDBMS)

A database management system that supports true data, transactional integrity, and a server-side relational database engine. SQL Server is an RDBMS.

Relative Distinguished Name

The portion of an object’s name that is an attribute of the object itself.

Relative Expense

This method calculates any defined measure of the cost (including the monetary cost) to use a given link.

Relative ID (RID) Master

The domain controller that is responsible for generating unique identifiers for each of the domains within an Active Directory environment.

Relay Host

An SMTP host designated to receive all outgoing SMTP mail. The relay host then forwards the mail to the relevant destination.

Reload

An event or command that causes Cisco routers to reboot.

Remote Access Policy

A policy that specifies who is authorized to access an RAS server.

Remote Access Profiles

Allows an administrator to determine who can actually use dial-up capabilities. Remote access profiles work on individual accounts, whereas remote access policies work on groups of users.

Remote Access Service (RAS)

A service that allows network communications to be established over PSTN lines with modems. The computer initiating the connection is called the RAS client; the answering computer is called the RAS host. See also Modem and Public Switched Telephone Network.

Remote Access Service (RAS) Server

A Windows Server computer that is running the Routing and Remote Access service. An RAS server authenticates and services requests from remote clients to connect to the network. See also
Routing and Remote Access Service.

Remote Administration Mode

A Terminal Services mode that allows administrators to perform administrative tasks from virtually any client on the network. See also Terminal Services.

Remote Authentication Dial-In User Service (RADIUS) Server

A server that stores a central authentication database that allows administrators to manage RAS servers from a single location.

Remoteboot

The remoteboot service starts disk-less workstations over the network.

Remote Control

A feature used with Terminal Services to allow administrators to view or control a user’s session from another session. See also Terminal Services.

Remote Copy Protocol (RCP)

A protocol for copying files to or from a file system that resides on a remote server on a network, using TCP to guarantee reliable data delivery.

Remote Data Objects (RDO)

A COM (Component Object Model) encapsulation of the ODBC API. RDO is a very thin layer of software that provides an object model for calling the ODBC API.

Remote Delivery

The delivery of a message to a recipient that does not reside on the same server as the sender.

Remote Desktop Protocol (RDP)

The protocol used with Terminal Services to allow Terminal Services clients to connect to the Terminal Services server. The Terminal Services server sends and receives commands to and from the client by using RDP. See also Terminal Services, Terminal Services Client, and Terminal Services Server.

Remote Installation

Installation of Windows 2000 Professional performed remotely through Remote Installation Services (RIS). See also Remote Installation Services (RIS).

Remote Installation Preparation (RIPrep) Image

A type of image configured on a Remote Installation Services (RIS) server. An RIPrep image can contain the Windows 2000 operating system and applications. This type of image is based on a preconfigured computer. See also Remote Installation Services (RIS).

Remote Installation Preparation (RIPrep) Wizard

A remote installation tool used to create “images” of the configuration of a specific workstation. This method increases consistency in workstation rollouts and decreases the administrative effort required.

Remote Installation Services (RIS)

A Windows technology that allows the remote installation of Windows. An RIS server installs Windows on RIS clients. The RIS server can be configured with a CD-based image or a Remote Installation Preparation (RIPrep) image.

Remote Procedure Call (RPC)

A set of protocols for issuing instructions that can be sent over a network for execution. A client computer makes a request to a server computer and the results are sent to the client computer. The computer issuing the request and the computer performing the request are remotely separated over a network. Remote procedure calls are a key ingredient in distributed processing and client/server computing. See also Local Procedure Call and Interprocess Communications.

Remote Terminal Emulation (Telnet)

Telnet enables PCs and workstations to function as dumb terminals in sessions with hosts on internetworks. Telnet implementations are available for most end-user platforms, including UNIX, DOS, Windows, and Macintosh OS.

Removable Media Database

A SQL Server database created on a removable medium, such as a CD-ROM or floppy disk. Removable media databases can be sent to another location and used from that location.

Removable Storage

A Windows utility used to track information on removable storage media, which includes CDs, DVDs, tapes, and jukeboxes containing optical discs.

REN

Renames a file or files.

Rename

The action by which a user or program assigns a new name to a file. Viruses may rename program files and take the name of the file so running the program inadvertently runs the virus. Anti-virus programs may rename infected files so they are unusable until they are manually cleaned or deleted.

RENAME

Renames a file or files.

Rendering

The process that determines whether or not a print job needs further processing once that job has been sent to the spooler. The processing is used to format the print job so that it can print correctly at the print device. See also Print Device.

Repeaters

Repeaters generate a signal and are used to expand LANs beyond cabling limits.

REPLACE

Replaces files.

Replica

A copy of a public folder located on an Exchange server.

Replication

1. The transferring of a copy of data to another location, such as another server or site. See also Directory Replication and Public Folder Replication.
2. The process by which a virus makes copies of itself in order to carry out subsequent infections. Replication is one of the major criteria separating viruses from other computer programs.

Replication, Intersite

The transfer of information between domain controllers that reside in different Active Directory sites.

Replication, Intrasite

The transfer of information between domain controllers that reside within the same Active Directory site.

Replication Latency

The delay period (the latency) that occurs after a change to the directory before the DS begins the directory replication process. Latency allows multiple directory changes to be sent during directory replication. The default replication latency period is 300 seconds.

Replication Partners

Two servers that replicate data back and forth.

Replicator Group

A Windows built-in group that supports directory replication, which is a feature used by domain servers. Only domain user accounts that will be used to start the replication service should be assigned to this group.

Requester

See Redirector.

Request for Comments (RFCs)

The set of standards defining the Internet protocols as determined by the Internet Engineering Task Force and available in the public domain on the Internet. RFCs define the functions and services provided by each of the many Internet protocols. Compliance with the RFCs guarantees cross-vendor compatibility. See also Internet.

equest To Send (RTS)

An EIA/TIA-232 control signal requesting permission to transmit data on a communication line.

Reservation

An IP to MAC mapping that allows a DHCP server to always give the same IP address to a DHCP client.

Reset

To restart a computer without turning it off. Also known as Warm Boot.

Resident Extension

A resident extension is a memory-resident portion of a program that remains active after the program ends. It essentially becomes an extension to the operating system. Many viruses install themselves as resident extensions.

Resident Virus

A resident virus loads into memory and remains inactive until a trigger event. When the event occurs the virus activates, either infecting a file or disk, or causing other consequences. All boot viruses are resident viruses and so are the most common file viruses.

Resolver

DNS client computer that makes requests to a server; these requests ask the server to resolve a client DNS name into the corresponding IP address, or vice versa. See also DNS Client.

Resolver Program

Client software that queries a DNS database to map a domain name to its IP address.

Resolving an Address

The process of determining where (on which physical server) an object with a particular address resides.

Resource

Any component that you would like to use on the network. This could be anything from a file on another machine, to a printer located at the end of the hall, to even a certain task available by a specific program. See also Share.

Resource Records

Contains information about some resource on the network. There are several types of resource records.

RESTORE

Restores files that were backed up by using the BACKUP command.

Restore, Authoritative

Specifies that the contents of a certain portion of the Active Directory on a domain controller should override any changes on other domain controllers, regardless of their sequence numbers. An authoritative restore is used to restore the contents of the Active Directory to a previous point of time.

Restore Wizard

A Wizard used to restore data. The Restore Wizard is accessed through the Windows Backup utility.

Resultant Set of Policy (RSoP)

A new Windows Server 2003 tool that automatically calculates the actual policy for a user or group based on site, domain, and OU placement, as well as inheritance settings.

Return Key

The same as the Enter key.

Return on Investment (ROI)

The amount of time that a new technology will take to pay for itself in reduced costs.

Reverse Address Resolution Protocol (RARP)

The TCP/IP protocol that allows a computer that has a Physical layer address (such as an Ethernet address) but does not have an IP address to request a numeric IP address from another computer on the network. See also Transmission Control Protocol/Internet Protocol.

Reverse Lookup Zone

A database that helps computers translate IP addresses into DNS names.

RFC

See Request for Comments.

Rich-Text Format (RTF)

A Microsoft format protocol that includes bolding, highlighting, italics, underlining, and many other format types.

RIF

See Routing Information Field.

Ring

A network topology in which computers are arranged in a circle. Data travels around the ring in one direction, with each device on the ring acting as a repeater. Ring networks typically use a token-passing protocol.

Ring Speed

The data transfer speed of a token ring network. Possible values are 8 Mbps and 16 Mbps.

Ring Topology

Ring topologies are wired in a circle. Each node is connected to its neighbors on either side, and data passes around the ring in one direction only.

RIP

See Routing Information Protocol.

RIPrep Image

See Remote Installation Preparation Image.

RIS

See Remote Installation Services.

RISC

See Reduced Instruction Set Computer.

RJ-11

A commonly used modular telephone connector. RJ-11 is a four-wire (two pair) connector most often used for voice communications.

RJ Connector

See Registered Jack Connector.

RMDIR

Removes a directory.

Roaming User Profile

A user profile that is stored and configured to be downloaded from a server. Roaming user profiles maintain a consistent environment for the user among computers on the network. See also User Profile.

Rogue Program

A term the media use to denote any program intended to damage programs or data, or to breach a system’s security. It includes Trojan Horse programs, logic bombs, viruses, and more.

ROI

See Return on Investment.

Role

A group of permissions that define what activities a user or group can perform with regards to an object.

Roll Back

The ability of a database management system to abort a transaction against the database before the transaction is complete and return to a previous stable condition. See also Roll Forward and Transaction Processing.

Roll Forward

The ability of a database management system to recreate the data in the database by rerunning all the transactions listed in the transaction log. See also Roll Back and Transaction Processing.

ROM

Read Only Memory. The micro’s non-volatile memory. Data is written into this memory at manufacture and is not affected by power loss.

Root Bridge

Used with the Spanning-Tree Protocol to stop network loops from occurring. The root bridge is elected by having the lowest bridge ID. The bridge ID is determined by the priority (32,768 by default on all bridges and switches) and the main hardware address of the device. The root bridge determines which of the neighboring layer-2 devices’ interfaces become the designated and nondesignated ports.

Root Certificate Authority

The top-level CA, which signs its own certificate, asserting that it is a root.

Root Directory

The main disk directory under which a number of subdirectories can be created.

Root Domain

In DNS, the name of the top of the Internet domain hierarchy. Although the root domain does not have a name, it is often referred to as “.”.

Root Share

In the context of the Distributed file system (Dfs), a share used to replicate the Dfs root. Root shares are created on other member servers in a domain. See also Distributed File System and Dfs Root.

Routable Protocols

Protocols that support internetwork communication.

Route Discovery

The process a router uses to find the possible routes through the internetwork and then build routing tables to store that information.

Route Filters

Filters that allow you to pick and choose which networks you want to admit knowing and for which you want to accept announcements.

Route Poisoning

Used by various DV routing protocols in order to overcome large routing loops and offer explicit information about when a subnet or network is not accessible (instead of merely suggesting that the network is unreachable by not including it in updates). Typically, this is accomplished by setting the hop count to one more than the maximum. See also Poison Reverse Updates.

Route Processor (RP)

Also known as a supervisory processor, a module on Cisco 7000 series routers that holds the CPU, system software, and most of the memory components used in the router.

Route Summarization

In various routing protocols, such as OSPF, EIGRP, and IS-IS, the consolidation of publicized subnetwork addresses so that a single summary route is advertised to other areas by an area border router.

Route/Switch Processor (RSP)

A processor module combining the functions of RP and SP used in Cisco 7500 series routers. See also Route Processor and Switch Processor.

Routed Protocol

Routed protocols (such as IP and IPX) are used to transmit user data through an internetwork. By contrast, routing protocols (such as RIP, IGRP, and OSPF) are used to update routing tables between routers.

Router

1. A device that connects two dissimilar networks, and allows packets to be transmitted and received between them.
2. A connection between two networks that specifies message paths and may perform other functions, such as data compression. See also Network Layer.

Routing

The process of forwarding logically addresses packets from their local subnetwork toward their ultimate destination. In large networks, the numerous intermediary destinations a packet might travel before reaching its destination can make routing very complex.

Routing and Remote Access Service (RRAS)

A Windows Server service that allows an RAS server to connect mobile users to the network.

Routing Domain

Any collection of end systems and intermediate systems that operate under an identical set of administrative rules. Every routing domain contains one or several areas, all individually given a certain area address.

Routing Group

A collection of Exchange servers that can transfer messaging data to one another in a single-hop without going through a bridgehead. In general, Exchange servers within a single routing group have high-bandwidth, resilient network links between each other. Additionally, a routing group defines the boundary for public folder access.

Routing Group Connector (RGC)

A connector in Exchange that connects routing groups to one another. An RGC is uni-directional and can have separate configuration properties (such as allowable message types over the connection). Routing Group Connectors use the concept of local and remote bridgeheads to dictate which servers in the routing groups can communicate over the link. The underlying message transport for an RGC is either SMTP or RPC and it uses link state information to route messages efficiently.

Routing Information Field (RIF)

In source-route bridging, a header field that defines the path direction of the frame or token. If the Route Information Indicator (RII) bit is not set, the RIF is read from the source to destination (left to right). If the RII bit is set, the RIF is read from the destination back to the source, so the RIF is read right to left. It is defined as part of the Token Ring frame header for source-routed frames, which contains path information.

Routing Information Protocol (RIP)

A protocol used in both the TCP/IP and IPX/SPX protocol suites for the automatic building and distribution of routing tables. See also Transmission Control Protocol/Internet Protocol.

Routing Metric

Any value that is used by routing algorithms to determine whether one route is superior to another. Metrics include such information as bandwidth, delay, hop count, path cost, load, MTU, reliability, and communication cost. Only the best possible routes are stored in the routing table, while all other information may be stored in link-state or topological databases. See also Cost.

Routing Protocol

Any protocol that defines algorithms to be used for updating routing tables between routers. Examples include IGRP, RIP, and OSPF.

Routing Service

A component in Exchange that builds link state information.

Routing Table

A table kept in a router or other internetworking mechanism that maintains a record of only the best possible routes to certain network destinations and the metrics associated with those routes.

Row

In a SQL Server database, a complete set of columns within a single table; it represents a single entity in a table.

RP

See Route Processor.

RPC

See Remote Procedure Calls.

RRAS

See Routing and Remote Access Service.

RS-232

The most common serial communications system in use.

RSP

See Route/Switch Processor.

RTF

See Rich Text Format.

RTS

See Request To Send.

Rule

In a SQL Server database, an object that is assigned to a column so that data being entered must conform to standards you set. Rules can enforce domain integrity (a valid range of values). You can create rules to enable pattern matching, enable a range of values, or force a selection from a list of values.

RVP

The Microsoft published protocol that is used between the MSN Messenger service and the Instant Messaging server that is implemented on Exchange. RVP uses an extended subset of HTTP-DAV with an Extensible Markup Language (XML) payload to send subscriptions and notifications between Instant Messaging clients and servers.