R

RAID 0

A form of RAID that provides fast transfer of data but does not provide any fault tolerance.

RAID 1

A form of RAID that provides an additional copy of all data on a separate disk so that if one disk were to fail, all of the data would still be secure on the other disk. This form of RAID can be used on the partitions that contain the system and boot files.

RAID 5

A form of RAID that uses a group of hard disks, which are configured using parity data to provide fault tolerance so that if one disk were to fail, the data contained on all disks could be regenerated by the remaining disks. This type of RAID cannot be used on the partitions that contain the boot and system files.

radio frequency (RF)

Communication and control using radio waves in a specified frequency. Does not require line of sight.

recovery

The process of rebuilding a network after having lost functionality or data.

recovery agent

A second user (usually the Administrator) used to recover EFS-encrypted files when the original user is not available to decrypt the files.

redundant array of inexpensive disks (RAID)

Configurations consisting of more than one disk that are used to provide increased performance and/or fault tolerance.

Regional and Language Options

A setting in Control Panel that allows an administrator to add new languages that the computer can understand and that can be used to create documents. This might also require a special keyboard or a keyboard overlay.

regional settings

Configuration in Regional and Language Options that defines the method of displaying dates, times, currency and so on, based on a country and region.

registered ports

Port numbers ranging from 1024 to 49151 that are used by applications that do not use well-known ports but still need to have consistent port assignments.

Remote Access Server (RAS)

A remote access solution that is included with Microsoft Windows Server products. Its main function is to give users access to the network from a remote location as if they were actually sitting at their desks, although sometimes the access is much slower.

Remote Assistance

A tool in Windows XP that allows a user to request assistance from a more experienced user and enables the more experienced user to take control of a less experienced user's computer remotely to attempt to fix a problem.

Remote Authentication Dial-In User Services (RADIUS)

A protocol and service by which clients can be allowed to use a remote or wireless connection based on an authentication by third-party server, such as a domain controller.

remote connection

Any connection to a resource or service that is outside of the computer itself.

remote connectivity

The ability to connect to a network through another network or a series of networks.

Remote Desktop

A tool built into Windows XP that uses Remote Desktop Protocol (RDP) to connect to and control a remote computer provided that the remote computer is configured to allow the connection and that the user can log on to the remote computer.

Remote Desktop Protocol (RDP)

A protocol used by Microsoft to establish remote display and remote control capabilities between servers and clients on a Microsoft network.

removable storage devices

All types of devices that are used to store data, with the exception of hard drives.

replication

The process of sharing an updated database, such as with Active Directory or WINS servers.

request timed out

An error message received from ICMP when using the ping tool. This error usually indicates that no other network entity replied to the packets at all.

Reverse Address Resolution Protocol (RARP)

A protocol that works at the Network layer of the OSI model and resolves MAC addresses to IP addresses. RARP was used with diskless workstations to provide an IP address before DHCP servers were available.

reverse lookup queries

DNS queries that are used to resolve a known IP address to a hostname.

ring topology

A network topology that resembles a star topology but uses MSAUs and the token-passing technology.

RJ-11 (registered jack) connector

The most common connector for use on normal telephones. It can contain and connect two pairs of wires.

RJ-45 (registered jack) connector

The most common connector for use on network devices. It can contain and connect four pairs of wires.

Roll Back Driver

A new feature on Windows XP that allows you to easily return to a previous driver for a device when a driver upgrade fails.

router

A device that forwards traffic from one subnet to another using the "anding" mechanism and a routing table.

Routing and Remote Access Services (RRAS)

A Windows service that provides access to LAN resources to remote users through dial-up or VPN connections.

Routing Information Protocol (RIP)

A routing protocol that is part of the TCP/IP suite of protocols. RIP is one of the protocols that enables the communication of routers for the establishment of routes.