R

RAID

See redundant array of independent disks.

RAID-5 volume

A fault-tolerant volume with data and parity striped intermittently across three or more physical disks. Parity is a calculated value that is used to reconstruct data after a failure. If a portion of a physical disk fails, you can recreate the data that was on the failed portion from the remaining data and parity. Also known as a striped volume with parity.

RAM

See random access memory.

random access memory (RAM)

Memory that can be read from or written to by a computer or other devices. Information stored in RAM is lost when the computer is turned off. See also virtual memory.

rangeLower

Optional. An integer that specifies the lower value of the range of values for this attribute. All values set for this attribute must be greater than or equal to this value. If both rangeLower and rangeUpper are set, rangeLower must be less than rangeUpper. For integers, value means the value of the integer. For string syntaxes, value means the number of characters in the string. For octet strings, value means the number of bytes.

rangeUpper

Optional. An integer that specifies the upper value of the range of values for this attribute. All values set for this attribute must be less than or equal to this value. If both rangeLower and rangeUpper are set, rangeLower must be less than rangeUpper. For integers, value means the value of the integer. For string syntaxes, value means the number of characters in the string. For octet strings, value means the number of bytes.

raster fonts

Fonts that are stored as bitmaps; also called bit-mapped fonts. Raster fonts are designed with a specific size and resolution for a specific printer and cannot be scaled or rotated. If a printer does not support raster fonts, it will not print them.

rDnAttId

Specifies the ldapDisplayName of the attribute that will be the naming attribute for the new class -- if different than the default ("cn").

Use of a naming attribute other than "cn" is discouraged. Naming attributes should be drawn from the well-known set (OU, CN, O, L and DC) that is understood by all LDAP version 3 clients.

read-only memory (ROM)

A semiconductor circuit that contains information that cannot be modified.

recall

An operation that retrieves the removed, unnamed data attribute from remote storage and places it on the managed volume. The placeholder is replaced on the managed volume with a copy of the file from remote storage. Upon completion of the recall, the file becomes a premigrated file.

Record Level Input/Output (RLIO)

An IBM distributed database protocol that provides record level access to nonrelational data on IBM host operating systems, including MVS, OS/390, and OS/400.

recovery

The process of using a log file to restore a database to a consistent state after a system crash and to restore a database from a backup to the most recent state that is recorded in the log file after a media failure. See also authoritative restore.

recovery agent

An account that can be used to decrypt a file encrypted by using the Encrypting File System (EFS) if the file owner's decryption key becomes unavailable.

recovery log

See quorum log.

recursion

One of the three process types for DNS name resolution. In this process, a resolver (a DNS client) requests that a DNS server provide a complete answer to a query that does not include pointers to other DNS servers. When a client makes a query and requests that the server use recursion to answer, it effectively shifts the workload of resolving the query from the client to the DNS server. If the DNS server supports and uses recursion, it will contact other DNS servers as necessary (using iterative queries on behalf of the client) until it obtains a definitive answer to the query. This type of resolution allows the client resolver to be small and simple. See also iteration; iterative query; recursive query.

recursive name query

See recursive query.

recursive query

A query made to a DNS server in which the requester asks the server to assume the full workload and responsibility for providing a complete answer to the query. The DNS server then uses separate iterative queries to other DNS servers on behalf of the requester to assist in completing an answer for the recursive query. See also iteration; iterative query; recursion.

redirection

In UNIX, to send the standard output to a file instead of to the terminal or to take the standard input from a file instead of from the terminal.

redirector

See Windows 2000 Redirector.

redundant array of independent disks (RAID)

A method used to standardize and categorize fault-tolerant disk systems. Six levels gauge various mixes of performance, reliability, and cost. Windows 2000 provides three of the RAID levels: Level 0 (striping) which is not fault-tolerant, Level 1 (mirroring), and Level 5 (striped volume with parity). See also fault tolerance; mirrored volume; RAID-5 volume; striped volume.

referral

In Dfs, information that maps a DNS name in the logical namespace to the UNC equivalent name of a physical share. When a Dfs client gains access to a shared folder in the Dfs namespace, the Dfs root server returns a referral for the client to use in locating the shared folder. In DNS, a pointer to an authoritative DNS server that is authoritative for a lower level of the domain namespace. See also LDAP referral.

refresh

To update displayed information with current data.

refresh interval

In DNS, a 32-bit time interval that needs to elapse before the zone data is refreshed. When the refresh interval expires, the secondary server checks with a master server for the zone to see if its zone data is still current or if it needs to be updated by using a zone transfer. This interval is set in the start of authority (SOA) resource record for each zone. See also resource record; secondary server; start of authority (SOA) resource record; zone; zone transfer.

refresh rate

The frequency with which the video screen is retraced in order to prevent the image from flickering. The entire image area of most monitors is refreshed approximately 60 times per second.

registered ports

Ports in the range from 1024 -- 49151.

registry

In Windows 2000, Windows NT, Windows 98, and Windows 95, a database of information about a computer's configuration. The registry is organized in a hierarchical structure and consists of subtrees and their keys, hives, and entries.

registry boot

The default boot option used by most Microsoft DNS servers. When registry boot is used, the DNS service is started by using the DNS Service parameters and their values that are stored in the Windows 2000 registry. A Berkeley Internet Name Domain (BIND) boot file may be used as an alternative to this method of boot configuration for the DNS service. See also BIND boot file.

registry key

An identifier for a record or group of records in the registry.

regroup event

In a server cluster, when one node detects a communication failure with another cluster node, the first node's broadcast of a message to the entire cluster causing all members to verify their view of the current cluster membership.

relative distinguished name

The part of an object name that is an attribute of the object itself. For example, given the distinguished name of cn=JamesSmith,ou=Managers,dc=Reskit,dc=com, the relative distinguished name of the JamesSmith user object is cn=James Smith. The relative distinguished name of the parent object is ou=Managers. The relative distinguished name of the domain object is dc=Reskit.

relative ID (RID)

The part of a security ID (SID) that uniquely identifies an account or group within a domain. See also security ID.

relative ID master

The domain controller assigned to allocate sequences of relative IDs to each domain controller in its domain. Whenever a domain controller creates a security principal (user, group, or computer object), the domain controller assigns the object a unique security ID. The security ID consists of a domain ID that is the same for all security IDs created in a particular domain, and a relative ID that is unique for each security ID created in the domain. At any time, there can be only one relative ID master in a particular domain. See also Active Directory; domain controller; multimaster replication; operations master; replication.

relay agents

A small program that relays a certain type of message to others on a network. In TCP/IP networking, routers are used to interconnect hardware and software used on different subnets and forward IP packets between the subnets.

remote access policy

A set of conditions and connection parameters that define the characteristics of the incoming connection and the set of constraints imposed on it. Remote access policies determine whether a specific connection attempt is authorized to be accepted.

remote access server

A Windows 2000 Server--based computer running the Routing and Remote Access service and configured to provide remote access.

Remote Access Service (RAS)

A Windows NT 4.0 service that provides remote networking for telecommuters, mobile workers, and system administrators who monitor and manage servers at multiple offices.

remote access VPN connection

A connection made by a remote access client, a single user, that connects to a private network. The VPN server provides access to the resources of the VPN server or to the entire network to which the VPN server is attached. The packets sent from the remote client across the VPN connection originate at the remote access client computer.

remote computer

A computer that is accessible only by using a communications line or a communications device, such as a network adapter or a modem.

remote installation boot floppy (RBFG.exe)

A tool that is used to generate a remote installation boot floppy disk. The remote installation boot floppy disk is used to start the process of remote operating system installation for computers which lack a supported PXE-based remote boot ROM. The remote installation floppy disk simulates the PXE boot process on computers with a supported Peripheral Component Interconnect (PCI) network adapter.

Remote Installation Preparation wizard (RIPrep.exe)

A component in Remote Installation Services that is used to create operating system images and to install them on the RIS server.

Remote Installation Service (RIS)

Software services that allow a user to install Windows 2000 Professional from a Remote Install server with minimal interaction.

Remote Installation Service setup (RISetup.exe)

A component in Remote Installation Services that is used to set up the RIS server.

remote operating system installation

See Remote Installation Services (RIS).

remote procedure call (RPC)

A message-passing facility that allows a distributed application to call services that are available on various computers in a network. Used during remote administration of computers.

remote storage

For Windows 2000 Server, removable tapes in a library used for secondary data storage. Specified tapes used for secondary data storage are managed by Remote Storage and contain data that is either stored on, or has been removed from, local storage to free up disk space. See also local storage.

Remote Storage

A hierarchical storage management application that migrates data from primary storage to secondary storage. Hierarchical storage management makes sure that data is stored in the most cost-effective method possible. Frequently accessed data is stored on high-performance disks, while data that is not accessed as often is migrated to cheaper media until it is needed again.

Removable Storage

A service used for managing removable media (such as tapes and discs) and storage devices (libraries). Removable Storage allows applications to access and share the same media resources. See also library.

renewal interval

The amount of time available to a client to refresh its name with the WINS server. If the name is not renewed by the end of this period, the name is released. Renewal interval is also known as the name refresh timeout, or the Time To Live (TTL).

repackaging

The process of converting an earlier version of an application to take advantage of many Windows Installer features, including the ability to advertise the application to users, the ability of the software to repair itself if essential files are deleted or corrupted, and the ability of users to install the application with elevated privileges.

reparse points

New NTFS file system objects that have a definable attribute containing user-controlled data and are used to extend functionality in the input/output (I/O) subsystem.

RepeatKeys

A feature that allows users with mobility impairments to adjust the repeat rate or to disable the key-repeat function on the keyboard. (See FilterKeys)

replay attack

An attempt to circumvent an authentication protocol by copying authentication messages from a legitimate client and then resending them during the impostor's own authentication to the server. See also nonce.

replica

In Active Directory replication, a copy of a logical Active Directory partition that is synchronized through replication between domain controllers that hold copies of the same directory partition. "Replica" can also refer to the composite set of directory partitions held by any one domain controller. These are specifically called a directory partition replica and server replica, respectively. See also full replica; partial replica.

replicated update

In Active Directory replication, a write to a property on one replica as the result of replication of an update that originated at another replica. See also originating update.

replication

The process of copying data from a data store or file system to multiple computers that store the same data for the purpose of synchronizing the data. In Windows 2000, replication of the directory service occurs through Active Directory replication, and replication of the file system occurs through the File Replication service. See also Active Directory replication; Distributed file system; File Replication service.

replication convergence

In multimaster replication, the guarantee that all replicas eventually converge on the same set of values if the system is allowed to reach a steady state, in which no new updates are occurring and all previous updates have been completely replicated. In a steady state, all replicas of a directory partition have the same objects, the same attributes, and the same values. See also Active Directory replication; loose consistency; multimaster replication.

replication cost

A numeric setting on a site link object. The total cost of a replication path between two sites is the sum of the costs of the links on the least costly route. Higher cost numbers represent more expensive messages. When the Knowledge Consistency Checker selects a site to obtain a source for a given directory partition, it selects the site with the least cost.

replication latency

In Active Directory replication, the delay between the time an update is applied to a given replica of a directory partition and the time it is applied to some other replica of the same directory partition. A server will receive changes no sooner than either

· It is notified of a change from its neighbor in the same site, or

· Its periodic replication timer expires.

Latency is sometimes referred to as propagation delay. See also multimaster replication.

replication partner

A domain controller that acts as a replication source for a given domain controller. The Knowledge Consistency Checker determines which servers are best suited to replicate with each other, and generates the list of domain controllers that are candidates for replication partners from the list of domain controllers in the site on the basis of connectivity, history of successful replication, and matching of full and partial replicas. A domain controller has some number of direct replication partners with whom it replicates for a given directory partition. The other domain controllers in the site replicate transitively with this domain controller. See also store-and-forward replication.

replication topology

In Active Directory replication, the set of connections that domain controllers use to replicate information among themselves, both within sites and between sites. The site topology is defined by site link objects. The connection topology is defined by connection objects. See also Active Directory replication; connection object; domain controller; site link.

replication transport

The protocols that are used to transport replication data over the network. For intrasite replication, data is always transferred by using RPC over IP. For intersite replication, data is transferred using either RPC synchronous transport (RPC over IP) or intersite messaging asynchronous transport (SMTP over IP). The choice of transport is controlled by the transport object (IP or SMTP) within which the site links are created in Active Directory. Different transports have different characteristics that make them better suited to different environments.

Request for Comments (RFC)

A document that defines a standard. RFCs are published by the Internet Engineering Task Force (IETF) and other working groups.

reservation

A specific IP address within a scope permanently reserved for a specific DHCP client. Client reservations are made in the DHCP database using DHCP Manager and based on a unique client device identifier for each reserved entry. In QoS ACS, an allocation of network resources, contained in a Resource Reservation Protocol (RSVP) reservation request administered by the QoS Admission Control Service. See also Dynamic Host Configuration Protocol (DHCP).

reserved state

A state that indicates that a side is the second side of a two-sided medium. It is unavailable for allocation to all but the application that has already allocated the first side.

resolver

DNS client programs used to look up DNS name information. Resolvers can be either a small "stub" (a limited set of programming routines that provide basic query functionality) or larger programs that provide additional lookup DNS client functions, such as caching. See also caching, caching resolver.

resource

Any part of a computer system or network, such as a disk drive, printer, or memory, that can be allotted to a program or a process while it is running. For Device Manager, any of four system components that control how the devices on a computer work. These four system resources are: interrupt request (IRQ) lines, direct memory access (DMA) channels, input/output (I/O) ports, and memory addresses. In a server cluster, an instance of a resource type; the Cluster service manages various physical or logical items as resources. See also direct memory access (DMA); input/output (IO) port; interrupt request (IRQ) lines; memory address.

Resource DLL

A dynamic-link library that defines default properties and behavior for a specific type of resource. The resource DLL contains an implementation of the Server Cluster API for a specific type of resource and is loaded into the address space of its Resource Monitor. See also dynamic-link library; Resource Monitor.

resource domain

A Windows NT domain that holds account data for workstations and resource computers (for example, file and print servers) associated with an account or master domain. See account domain; master domain.

Resource Monitor

The server cluster component that manages communication between a node's Cluster service and one or more of its resources. See also node; resource.

resource record (RR)

Information in the DNS database that can be used to process client queries. Each DNS server contains the resource records it needs to answer queries for the portion of the DNS namespace for which it is authoritative.

resource record set (RRset)

A collection of more than one resource record returned in a query response by a DNS server. Resource record sets (RRsets) are used in responses where more than one record is part of the answer. See also resource record.

Resource Reservation Protocol (RSVP)

A signaling protocol that allows the sender and receiver in a communication to set up a reserved highway for data transmission with a specified quality of service.

resource type

A server cluster object used to manage resources of similar characteristics. A resource type is associated with a resource DLL that manages all the resources of that type in the cluster.

response time

The amount of time required to do work from start to finish. In a client/server environment, this is typically measured on the client side.

reverse domain

A special domain, named in-addr.arpa, that is used for IP address-to-name mappings (referred to as reverse lookup).

reverse lookup

A query in which the IP address is used to determine the DNS name for the computer.

reverse lookup zone

A zone that contains information needed to perform reverse lookups. See also reverse lookup.

revision level

One of three levels that can be viewed in Network Monitor traces which refer to Dfs client compatibility. Windows NT 4.0, Windows 95 and Windows 98 clients support Dfs revision level 2; Windows 2000 clients support revision level 3. There are no known version 1 clients. Dfs clients and servers negotiate the highest common protocol revision supported.

RFC

See Request for Comments.

RIP

See routing information protocol.

Rivest-Shamir-Adleman (RSA) cryptographic algorithms

A widely used set of public key algorithms that are available from RSA Data Security, Inc. The RSA cryptographic algorithms are supported by the Microsoft Base Cryptographic Service Provider and the Microsoft Enhanced Cryptographic Service Provider.

roaming profile

A set of user-specific settings in a single location on a server so that users can move from computer to computer while retaining the same profile.

roaming user profile

A server-based user profile that is downloaded to the local computer when a user logs on and is updated both locally and on the server when the user logs off. A roaming user profile is available from the server when logging on to any computer that is running Windows 2000 Professional or Windows 2000 Server. When logging on, the user can use the local user profile if it is more current than the copy on the server.

rogue DHCP server

An unauthorized DHCP server.

rolling upgrade

In a cluster, the process of upgrading cluster nodes by turns while the other nodes continue to provide service.

root

The highest or uppermost level in a hierarchically organized set of information. The root is the point from which further subsets are branched in a logical sequence that moves from a broad or general focus to narrower perspectives.

root authority

See root certification authority.

root certificate

A self-signed certification authority certificate. It is called a root certificate because it is the certificate for the root authority. The root authority must sign its own certificate because there is no higher certifying authority in the certification hierarchy. See also certificate; certification authority; root certification authority.

root certification authority

The most trusted certification authority (CA), which is at the top of a certification hierarchy. The root CA has a self-signed certificate. Also called the root authority. See also certification authority; certification path; root certificate.

root directory

The top-level directory (or folder) on a computer, a partition or volume, or Macintosh-accessible volume. See also directory tree.

root DNS server

A DNS server authoritative for the root of the Internet. See also DNS server.

root domain

The beginning of the Domain Name System (DNS) namespace. In Active Directory, the initial domain in an Active Directory tree. Also the initial domain of a forest.

root hints

Local information stored on a DNS server that provides helping resource records to direct the server to its root servers. For the Microsoft DNS service, the root hints are stored in the file Cache.dns, located in the \%SystemRoot%\System32\Dns folder. Root hints are also called cache hints. See also authoritative; namespace; root; root servers; systemroot.

root hints file

See root hints.

root servers

DNS servers that are authoritative for the root of the namespace. See also authoritative; namespace; root; root hints.

round robin

A simple mechanism used by DNS servers to share and distribute loads for network resources. Round robin is used to rotate the order of resource record (RR) data returned in a query answer when multiple RRs exist of the same RR type for a queried DNS domain name.

round trip time estimation (RTTE)

The amount of time necessary to complete a round trip from sender to receiver and back.

route determination process

The process of selecting an interface and forwarding IP address based on the destination IP address of an IP datagram and the contents of the IP routing table.

route flapping

A condition on an internetwork in which a network segment becomes intermittently available.

route summarization

The practice of combining multiple network IDs into a single route in the routing table. With proper planning, hierarchical routing infrastructures can use route summarization.

routemon utility

A scripting utility for the Routing and Remote Access service that is intended as a command-line alternative to the router administration user interface available through the Routing and Remote Access Manager.

router

A network device that helps LANs and WANs achieve interoperability and connectivity and that can link LANs that have different network topologies, such as Ethernet and Token Ring.

router discovery

The use of Internet Control Message Protocol (ICMP) messages to provide fault tolerance for the configuration of a host's default gateway.

router-to-router VPN connection

A connection made by a router that connects two portions of a private network. The VPN server provides a routed connection to the network to which the VPN server is attached. On a router-to-router VPN connection, the packets sent from either router across the VPN connection typically do not originate at the routers.

routing

The process of forwarding a packet through an internetwork from a source host to a destination host.

routing domain

A collection of contiguous network segments connected by routers that share the routing information for the routes within the domain.

Routing Information Protocol (RIP)

An industry standard distance vector routing protocol used in small to medium sized IP and IPX internetworks.

routing infrastructure

The structure and topology of the internetwork.

routing loop

A path through an internetwork for a network ID that loops back onto itself.

routing protocol

A series of periodic or on-demand messages containing routing information that is exchanged between routers to exchange routing information and provide fault tolerance. Except for their initial configuration, dynamic routers require little ongoing maintenance, and therefore can scale to larger internetworks.

routing table

A database of routes containing information on network IDs, forwarding addresses, and metrics for reachable network segments on an internetwork.

routing table maintenance protocol (RTMP)

A distance vector routing protocol used on AppleTalk internetworks.

RSA cryptographic algorithms

See Rivest-Shamir-Adleman (RSA) cryptographic algorithms.

rules

An IPSec policy mechanism that governs how and when an IPSec policy protects communication. A rule provides the ability to trigger and control secure communication based on the source, destination, and type of IP traffic. Each rule contains a list of IP filters and a collection of security actions that take place upon a match with that filter list.