- PC - Buzz - 1 A B C D E F G H I J K L M N O P Q R S T U V W X Y Z *

R/2, R/3

> SAP

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RACF = Resource Access Control Facility

an IBM security product for large systems

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RAD = Rapid Application Development

as Java, Access, PowerBuilder, Notes, Paradox, Delphi, Visual Basic etc

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RADIUS = Remote Authentication Dial-In User Service

Provides a central security administration system for managing authentication servers. Authentication information about all network users is stored in individual profiles. RADIUS is used in conjunction with CHAP and can administer multiple security systems across complex networks

RADIUS is a client/server protocol and software that enables remote access servers to communicate with a central server to authenticate dial-in users and authorize their access to the requested system or service. RADIUS allows a company to maintain user profiles in a central database that all remote servers can share. It provides better security, allowing a company to set up a policy that can be applied at a single administered network point. Having a central service also means that it's easier to track usage for billing and for keeping network statistics. Created by Livingston (now owned by Lucent), RADIUS is a de facto industry standard used by Ascend and other network product companies and is a proposed IETF standard.

> CHAP, TACACS

What is RADIUS?
Lucent Technologies: a white paper on RADIUS.
Funk: A Directory of RADIUS-Compatible Products and Services.
Getting Acquainted with RADIUS

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RAID = Redundant Array of Inexpensive Disks, Redundant Array of Independent Disks

Fault tolerance and/or improved performance - implemented in hardware (expensive) or software (as in Windows NT)
All drives should be SCSI

RAID 0

- stripes without parity - no redundancy - improves performance
- 2-32 disks form a single large partition - data are accessed in parallel across all disks (stripes).
- supported by Windows NT.

RAID 1

- mirroring and duplexing - redundancy - two disks - one mirrors the content of the other. If either disk fails, the other takes over automatically
- supported by Windows NT Server.

RAID 3

- stripes with ECC - like RAID 0, but parity information is stored on one of the disks - Error correcting code allow data recovery (reconstruction) if one disk fails

RAID 5

- stripes with parity - like RAID 3, but parity information is also stored on all disks.
- supported by Windows NT Server with 3-9 disk drives or partitions

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RAM = Random Access Memory

Hukommelse i computeren. Hver byte i hukommelsen har en bestemt lager-adresse.
'Random Access' betyder 'tilfældig adgang' - d.v.s. data kan læses og skrives på vilkårlige hukommelses-adresser (til forskel fra den 'serielle adgang', som gælder for databånd).

 

RAM kaldes også 'arbejdslager' fordi alle data (programmer, dokumenter o.s.v), som computerens processor (CPU) arbejder med er indlæst i RAM.
RAM-hukommelsen mister sit indhold, når stømmen afbrydes.
Når der tændes for strømmen, er RAM i første omgang tom, så processoren starter med at udføre programmer, som findes fast i computernes BIOS-ROM. Startprogrammet her indlæser operativsystemet i RAM.
 

> CAS, CMOS, DDR, DIMM, DLT, DRAM, ECC, EDO, PRAM, RAS, RDRAM, SDRAM, SIMM, SRAM, VRAM, WRAM
> Expanded memory (EMS)
> Extended memory (XMS)
> ROM
 

www.tomshardware.com/guides.ram.html
www.arstechnica.com/paedia/r/ram_guide/ram_guide.part1-1.html : RAM Guide

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Rambus

Founded in March 1990, by Dr. Mike Farmwald and Dr. Mark Horowitz, Rambus Inc. developed revolutionary technology for use in the semiconductor industry. Using a unique business model, Rambus develops and licenses advanced chip connection technology that enables semiconductor manufacturers to produce scalable bandwidth, memory and ASIC devices. The advantage of this technology is its high bandwidth and scalability - making it easy for semiconductor manufacturers to keep pace with the demands of today's rapidly changing microprocessor and controller speeds. Rambus and its partners provide technology that is significantly faster than conventional dynamic-random-access-memory (DRAM) devices. A single Rambus DRAM device (RDRAM‘) transfers data at speeds up to 1.6 GB/sec and by 2005 this will be 2.4 GB/sec.
 

>RDRAM, DRDRAM, RIMM

www.rambus.com/

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RAMDAC = Random Access Memory Digital-to-Analog Converter

[webopedia] : a single chip on video adapter cards. The RAMDAC's role is to convert digitally encoded images into analog signals that can be displayed by a monitor. A RAMDAC actually consists of four different components - SRAM to store the color map and three digital-to-analog converters (DACs), one for each of the monitor's red, green, and blue electron guns.

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.rar

fil pakket med WinRAR

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RAS = Remote Access Server

a host on a LAN with access - via modem - to other host/network

 

RAS = Remote Access Service

Windows software for access - via modem - to other host/network.
Remote user dials in to a server running RAS that connects user as a network node via modems
= DUN (Dial-up-networking)
RAS client in Windows 95
RAS server (for a single remote client) in Plus! pack
RAS client and server (for single client) in Windows 98 and NT Workstation
Full RAS (up to 256 simultaneous clients - remote nodes) in NT Server
 
>NDISWAN

 

RAS = Row Address Strobe

- in RAM access CAS

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RASC = Recreational Software Advisory Council

Rating-system, som bruges i MS Internet Explorer til at begrænse adgangen til Internettet
(Internet Options > Content > Content Advisor > Enable/Settings)

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RC2, RC4 = Ron's Code, Rivest's Cipher

An agreement between the Software Publishers Association (SPA) and the United States government gives RC2 and RC4 special status by means of which the export approval process is simpler and quicker than the usual cryptographic export process. However, to qualify for quick export approval a product must limit the RC2 and RC4 key sizes to 40 bits; 56 bits is allowed for foreign subsidiaries and overseas offices of United States companies. An additional string (40 to 88 bits long) called a salt can be used to thwart attackers who try to precompute a large look-up table of possible encryptions. The salt is appended to the encryption key, and this lengthened key is used to encrypt the message. The salt is then sent, unencrypted, with the message. RC2 and RC4 have been widely used by developers who want to export their products; DES is almost never approved for export.

 

RC2

is a variable key-size block cipher designed by Ron Rivest for RSA Data Security.  It is faster than DES and is designed as a "drop-in" replacement for DES. It can be made more secure or less secure than DES against exhaustive key search by using appropriate key sizes. It has a block size of 64 bits and is about two to three times faster than DES in software.

 

RC4

is a stream cipher designed by Rivest for RSA Data Security, Inc. It is a variable key-size stream cipher with byte-oriented operations. The algorithm is based on the use of a random permutation. Analysis shows that the period of the cipher is overwhelmingly likely to be greater than 10100. Eight to sixteen machine operations are required per output byte, and the cipher can be expected to run very quickly in software. The algorithm has been scrutinized by independent analysts and it is considered secure. The RC4 stream cipher has a special status by which export from the U.S. can often be facilitated. RC4 is used for file encryption in products such as RSA SecurPC. It is also used for secure communications, as in the encryption of traffic to and from secure websites using the SSL protocol.

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RDBMS = Relational DataBase Management System

- stores data in many related tables
Ex: Borland/Corel Paradox, Lotus Approach, Microsoft Access

> DBMS

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RDISK

Windows NT/2000 program, som benyttes til at fremstille en 'Emergency Repair Disk' (ERD). Programmet fulgte med Win NT4 men ikke med Win 2000, som benytter Windows Backup til alle former for backup incl. ERD.
 

support.microsoft.com/default.aspx?scid=KB;en-us;q122857 : RDISK /S and RDISK /S- Options in Windows NT
support.microsoft.com/default.aspx?scid=KB;en-us;q126464 : Repair Disk Utility Does Not Update SAM and Security Hives
support.microsoft.com/?kbid=216337 : Rdisk.exe Is Not Included with Windows

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RDRAM = Rambus Dynamic Random Access Memory

[whatis] : RDRAM is a memory subsystem that promises to transfer up to 1.6 billion bytes per second. The subsystem consists of the random access memory, the RAM controller, and the bus (path) connecting RAM to the microprocessor and devices in the computer that use it. Direct Rambus (DRDRAM), a technology developed and licensed by the Rambus Corporation, will be used with microprocessors beginning in 1999. High-speed RAM is expected to accelerate the growth of visually intensive interfaces such as 3-D, interactive games, and streaming multimedia. Rambus is intended to replace the current main memory technology of dynamic random access memory (DRAM). Much faster data transfer rates from attached devices such as videocams using FireWire and the Accelerated Graphics Port (AGP) make it important to reduce the bottleneck in getting data into the computer, staging it in RAM, and moving it throught the microprocessor and to the display or other output devices.
 
[webopedia] : a type of memory (DRAM) developed by Rambus, Inc. Whereas the fastest current memory technologies used by PCs (SDRAM) can deliver data at a maximum speed of about 100 MHz, RDRAM transfers data at up to 800 MHz. In 1997, Intel announced that it would license the Rambus technology for use on its future motherboards, thus making it the likely de facto standard for memory architectures. However, a consortium of computer vendors is working on an alternative memory architecture called SyncLink DRAM (SLDRAM).
RDRAM is already being used in place of VRAM in some graphics accelerator boards. As of late 1999, Intel has been using RDRAM in its Pentium III Xeon processors and more recently in its Pentium 4 processors. Intel and Rambus are also working a new version of RDRAM, called nDRAM, that will support data transfer speeds at up to 1,600 MHz.
 

www.chipcenter.com/memory/main13.html : Rambus RDRAM

>DRDRAM, SLDRAM

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Red Book

> TNI

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redirector

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Regedit

Editor for registreringsdatabasen i Windows
> Scanreg

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Registreringsdatabasen

i Windows 95/98/2000/XP - består af filerne USER.DAT og SYSTEM.DAT i WINDOWS-mappen.
- redigeres med Regedit
- i DOS kan Scanreg benyttes til sikkerhedskopiering og reparation
- DLL og OCX-filer kan registreres med regsvr32
 

www.winguides.com/registry/

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regsvr32

Windows-program til registrering af DLL og OCX-filer. >Start >Kør "regsvr32" giver en hjælpedialog.
Ex: regsvr32 \windows\system\MSWINSCK.OCX
>registreringsdatabasen

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repeater

Arbejder på fysisk lag - gendanner ("forstærker") signal-bits og sender dem videre - evt fra et medium til et andet.
En repeater sammenkobler to fysiske segmenter til ét logisk segment.
Multiport repeater = hub.
> bridge, switch, router

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RFC = Request For Comments

- documents Internet standards and protocols.

 

rfc.sunsite.dk/
www.networksorcery.com/enp/default0501.htm

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RFI = Radio Frequency Interference

> EMI

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RFID= Radio Frequency Identification

 

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RG-nn = Radio Grade

koaksialkabel, coax cable:

8		50 ohm tykt ethernet 10base5
11		50 ohm tykt ethernet 10base5
58		50 ohm tyndt ethernet 10base2
59		75 ohm kabel-TV
62		93 ohm ARCnet, IBM terminaler

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RGB = Red, Green, Blue

Farvemodel som benyttes til computerskærme, TV-skærme og andre medier, hvor farverne dannes med lys i de tre grundfarver: rød, grøn og blå. Disse farver giver tilsammen farven 'hvid'.
 

Red	Green	Blue

Mange bitmapbilleder - fx .bmp og .jpg - benytter denne model, hvor farven i hvert billedpunkt (pixel) bestemmes af 3 bytes (24 bits) med værdier for rød, grøn og blå. Da 8 bits kan angive 256 forskellige værdier, kan disse billedformater gengive 256*256*256 = ca 16 millioner forskellige farver.

> CMYK, HSB
> alfa-kanal, JPG, PNG

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RIMM = Rambus Inline Memory Module

[whatis] : In a computer, a RIMM is a memory module developed by Kingston Technology Corp. that takes up less space inside the computer than the older DIMM module and has different PIN characteristics. A RIMM has a 184-pin connector and an SO-RIMM module has a 160-pin connector. An SO-RIMM is smaller and is used in systems that require smaller form factors. While RIMM is commonly believed to stand for "Rambus inline memory module," Kingston Technology has trademarked "RIMM" and uses only that term. A RIMM module consists of RDRAM chips that are attached using a thin layer of solder, a metal alloy that, when melted, fuses metals to each other. Solder balls on each chip create a metal pathway used to conduct electricity.

>Rambus

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ring

ring network, ring topology
[MS-CD]: A LAN (local area network) in which devices (nodes) are connected in a closed loop, or ring. Messages in a ring network pass around the ring from node to node in one direction. When a node receives a message, it examines the destination address attached to the message. If the address is the same as the node's, the node accepts the message; otherwise, it regenerates the signal and passes the message along to the next node in the ring. Such regeneration allows a ring network to cover larger distances than star and bus networks. The ring can also be designed to bypass any malfunctioning or failed node. Because of the closed loop, however, adding new nodes can be difficult.
> tolpologi, token ring network
> bus network, star network

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RIP = Raster Image Processor

 

RIP = Routing Information Protocol

i Netware og TCP/IP
Dynamisk routing. Angiver hvordan routere udveksler router-tabel informationer

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RISC = Reduced Instruction Set Computer

ex: DEC Alpha (AlphaStation, AlphaServer), MIPS 4000, Pentium Pro, PowerPC (Apple Macintosh)
> CISC

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RJ-nn

stik til parsnoet kabel
-11 2 par
-45 4 par: telefon-kobling (UTP)
> TP

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rlogin

TCP/IP protocol for remote login to interactive service
> telnet, tn3270, URL

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RMI = Remote Method Invocation

 

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RMON = Remote Monitoring Capability

With RMON, a SNMP agent can trap network messages and display them in cleartext on a workstation.

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RNAAPP = Remote Network Access Application

Et program som startes automatisk, når man etablerer forbindelse til Internettet med 'Netværk via modem' (Dial-up Networking). Når forbindelsen afbrydes burde RNAAPP også slutte - men det gør det som regel ikke: med Ctrl-Alt-Del kan man se, at programmet stadig er aktivt.
RNAAPP kan være årsag til mange problemer med Internet-forbindelsen - se:

www.modemhelp.net/newsletter/dun/combatrnaapp.shtml : A Techie's Guide to Combating RNAAPP.EXE
www.cinet.net/support/kb/tech/tech18.html   : RNAAPP caused an invalid page fault in RNAAPP.EXE
support.microsoft.com/support/kb/articles/q182/5/89.asp   : Err Msg: RNAAPP Caused an Invalid Page Fault in Module <Unknown>

>DUN

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roaming

Brug af et udenlandsk mobilselskabs netværk.

 

[WhatIs]: roaming service is the ability to get local access to the Internet when away from home. For example, if you are travelling to Hong Kong, you can call a designated ISP in Hong Kong. Instead of paying long distance charges to your home ISP, you pay the local phone connection charge in Hong Kong and possibly a modest additional charge for the service. Roaming service is made possible through ISPs who have cooperative agreements to grant each others' customers local access to the Internet.

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ROLAP = Relational OLAP

Relational OLAP tools extract data from traditional relational databases. Using complex SQL statements against relational tables, ROLAP is able to create multidimensional views on the fly. ROLAP tends to be used on data that has a large number of attributes, where it cannot be easily placed into a cube structure. For example, customer data with numerous descriptive fields are typically ROLAP candidates, rather than financial data.

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ROM = Read Only Memory

Computer hukommelse som kun kan læses - ikke skrives d.v.s. indholdet kan ikke ændres.
ROM findes i en chip (BIOS) på bundkortet og på grafikkortet.
> CD-ROM, RAM

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router, routing

En "router" kaldes også en "Packet-switching Node" og "Network-layer gateway"
Forbinder netværk. Vælger rute for data-pakker i Internet trafik.
Arbejder på lag 3 (netværkslag) - læser logiske adresser - benytter router-tabeller og rutnings-algoritmer (>RIP). 
Evt. Indkapsling af protokoller - fx IPX/SPX indkapslet i IP
Evt. Sikkerhedsfunktioner:
- Kryptering
- Firewall-funktion - "Filtrerende Router" - filtrering af logiske adresser (lag-3)
NB: en ægte Firewall opererer på flere, højere lag.

 

[IT-Lex]: Anvendes i datanet som betegnelse for en enhed, der forbinder to net. Der er først og fremmest tale om funktioner, der hører til i netværkslaget i OSI, dvs. rutnings-funktioner, men der kan også ske konvertering i det fysiske lag og mellem protokollerne i dataoverførselslaget. En router er naturligt rettet mod bestemte protokoller, så der uden for OSI kan tales om f.eks. en IP-router, dvs. en router, der kender IP-protokollens adresse- og rutedataformat.
En router kan ofte konfigureres til at begrænse trafikken til kun at kunne finde sted mellem bestemte adresser, en filterfunktion. Dette kan benyttes til at gennemføre et øget sikkerhedsniveau i nettet på den ene side af routeren.

 

[MS-CD]: An intermediary device on a communications network that expedites message delivery. On a single network linking many computers through a mesh of possible connections, a router receives transmitted messages and forwards them to their correct destinations over the most efficient available route. On an interconnected set of LANs (local area networks)--including those based on differing architectures and protocols--using the same communications protocols, a router serves the somewhat different function of acting as a link between LANs, enabling messages to be sent from one to another.

 

[WhatIs]: On the Internet, a router is a device or, in some cases, software in a computer, that determines the next network point to which a packet should be forwarded toward its destination. The router is connected to at least two networks and decides which way to send each information packet based on its current understanding of the state of the networks it is connected to. A router is located at any juncture of networks or gateway, including each Internet point-of-presence. A router is often included as part of a network switch.
A router creates or maintains a table of the available routes and their conditions and uses this information along with distance and cost algorithms to determine the best route for a given packet. Typically, a packet may travel through a number of network points with routers before arriving at its destination.

 

Router-tabeller
indeholder adresse-data, som routeren benytter til at beslutte, hvilken vej data skal sendes. Tabellen indeholder adresser på andre routere, som kan nås i 'næste hop' - og informationer om destinations-adresser, som kan nås via hver af disse routere.

 

Statisk rutning : manuel opdatering af rutning-tabeller - administratoren har fuld kontrol - større sikkerhed
Dynamisk rutning : opdatering vha rutnings-protokoller:
- Distance-vector : routerne sender rute-tabeller til hinanden fx hvert minut (RIP)
- Link-state : opdateringer sendes når der er ændringer (NLSP, OSPF, IGRP)

 

Edge router : a router that interfaces with an ATM network.
Routing bridge or brouter : a network bridge combined with a router.
Multiport router : Nyere router der kan fungere som backbone ('collapsed backbone')
 

> bridge, switch, gateway

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RPC = Remote Procedure Call

is used in client/server applications based on MS Windows operating systems. Clients run procedures on a server (DLT)
ex: Print Provider (Windows 95/NT).
NT 3.51-: RPC messages use 40-bit encryption for secure data transmission
Uses IP-port 135

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RS-232

standard for asynkron kommunikation via seriel port (COM). 25 ben - ofte bruges kun 9. Tegn-orienteret med start-bit og stop-bit + evt paritet-bit

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RSA = Rivest-Shamir-Adleman

algoritme til kryptering - benyttes i PGP

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RSI = Repetitive Strain Injury

fx museskade

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Runway

Array of dishes directing and communicating with US satellites, including Vortex satellites operating over Europe and Asia. May have been complemented or replaced by new system called Rutley.
> COMINT

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