R

RAID (Redundant Arrays of Inexpensive Disks)

A method of storing data on multiple hard drives, allowing the overlapping of I/O operations. Depending on the level of RAID, there are either fault-tolerant or performance advantages.

RAID 0

A RAID configuration that employs data striping but lacks redundancy because there is no parity information recorded. As a result, RAID 0 offers no fault tolerance, but it does offer increased performance.

See also [RAID 5]

RAID 1

A fault-tolerant method that uses disk mirroring to duplicate the information stored on a disk.

RAID 2

A fault-tolerant method that uses disk striping with error correction.

RAID 3

A fault-tolerant method that uses disk striping with a single disk for parity.

RAID 4

A fault-tolerant method that uses disk striping with a single disk for parity. Striping is done across the disks in blocks.

RAID 5

A fault-tolerant method that uses disk striping with distributed parity. Striping is done across the disks in blocks.

RAID 10

Also referred to as RAID 1/0, a RAID configuration in which stripe sets (RAID 0) are mirrored (RAID 1). This combination provides the fault-tolerant aspects of RAID 1 and the performance advantages of RAID 0.

RARP (Reverse Address Resolution Protocol)

A protocol, part of the TCP/IP protocol suite, that resolves MAC addresses to IP addresses. Its relative ARP resolves IP addresses to MAC addresses.

RAS (Remote Access Service)

A Windows NT/2000 service that allows access to the network through dial-up connections.

read-only

An assigned right that allows the user to open a file and look at the contents or to execute the file if it is an application. The user cannot change the file or delete it.

read-write

An assigned right that allows the user to open a file, to change a file, or to execute a file. The user cannot delete a read-write file in some network operating systems, but can in others. The user can create new files in the directory if he or she is granted read-write permissions to a directory.

remote control

In networking, having physical control of a remote computer through software such as PCAnywhere or Microsoft Systems Management Server.

remote node

A node or a computer that is connected to a network through a dial-up connection. Dialing in to the Internet from home is an example of the remote node concept.

repeater

A device that regenerates and retransmits signals on a network. Repeaters are usually used to strengthen signals going long distances.

resolver

A system that is requesting the resolution of a name to an IP address. This term can be applied to both DNS and WINS clients.

resource conflict

A problem that occurs when multiple devices are using the same IRQ or I/O address at the same time, usually causing the devices to fail and the program to halt.

restore

To copy data from backup media to a server. The opposite of back up.

RFC (Request for Comments)

The process by which standards relating to the Internet, the TCP/IP protocol suite, and associated technologies are created, commented on, and approved.

RG-58

A designation for the coaxial cable used in thin coaxial networks that operate on the Ethernet standard.

RI (ring in)

A connector that is used in an IBM Token Ring network on an MSAU to expand to other MSAUs on the network. The counterpart to the RO, the RI on the MSAU connects to the medium to accept the token from the ring.

rights

An authorization provided to users that allows them to perform certain tasks. The network administrator generally assigns rights. Slightly different from but often used with the term permissions.

RIP (Routing Information Protocol)

A protocol that uses hop count as a routing metric to control the direction and flow of packets between routers on an internetwork. There are versions of RIP for use on both TCP/IP- and IPX/SPX-based networks.

RJ-11 connector

A connector that is used with telephone systems and can have either four or six conductors. A red/green pair of wires is used for voice and data; a black/white pair is used for low-voltage signals.

RJ-45 connector

An Ethernet cable connector that is used with twisted-pair cable and can support eight conductors for four pairs of wires.

RO (ring out)

A connector used in an IBM Token Ring network on an MSAU to expand to other MSAUs on the network. The counterpart to the RI, the RO on the MSAU connects to the medium to send the token out to the ring.

root

The top level of a file system or a directory services structure. Also, the name of the default administrative account on Unix and Linux systems.

route

The entire path between two nodes on a network.

router

A device that works at the network layer of the OSI model to control the flow of data between two or more network segments.

RS-232

A communications standard that defines the flow of serial communications and the particular functions assigned to the wires in a serial cable.