This glossary was written and prepared by Blair Bergum of  DNSnews.net
For additions or corrections to this glossary, please send email to glossary at dnsnews dot net

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RAID

Redundant Array of Inexpensive Devices. There are currently at least ten types of RAID:

1) RAID-0 striping but no redundancy

2) RAID-1 duplexed drives, no striping

3) RAID-2 striping across disks

4) RAID-3 striping across disks and the parity is dedicated to one disk

5) RAID-4 large striping, with no overlapping of I/O for read operations

6) RAID-5 has a rotating parity array, and all read and write operations can be overlapped

7) RAID-6 similar to RAID-5 but distributes parity over different drives to increase fault tolerance

8) RAID-7 uses a real-time controller and high speed caching

9) RAID-10 an array of stripes, where each stripe is RAID-1 (duplexed)

10)RAID-53 an array of stripes, where each stripe is RAID-3 (striping, and a dedicated parity drive)

Rdata

Resource Data, are the data records of the DNS zone.  It is composed of a variable length string of octets that describe the resource record.   Rdata includes the following Types:

A Address

CNAME  Canonical Domain Name

MX host acting as a mail exchanger for the domain

NS host name

PTR a domain name pointer

SOA Start of Authority fields

RDBMS

Relational Database Management System, where the data is stored in a set of relational tables. MySQL, is a RDBMS and can be used in conjunction with PHP scripting language to produce dynamic webpages.

RDS

1) Remote Data Service, provides client/server database functions using Open Database Connectivity (ODBC). See also ODBC.

2) Radio Data System, in the U.K. this is a radio transmission system that automatically tunes a radio to another station while a listener is travelling between transmitters if another station can be located that has a stronger signal and is carrying the same program. The RDS system is also called a "smart radio".

reachability

measures whether or not the path or connection exists across a connection. Note, reachability does not measure speed or performance.

real estate

the term given to refer to open racks, cabinets, and cages in a data center to house web servers for colocation.

recursion

is when a resolver transmits a recursive query to a name server to obtain the resource records for a given domain name. Recursive query is a formula that generates successive queries based upon the information from the preceding queries.

recursive query

see recursion.

Regional Registry

these are organizations responsible for allocating Internet protocol numbers to users in one of the three regional regions of the world. There is only one Regional Registry for each geographical region. Also known as RIR’s - Regional Internet Registries.

register domain

the act or process of registering for a domain name and paying all appropriate fees for the use of the domain name being registered.

registered jack

is the term used to denote U.S. based telephone jacks that are "registered" with the U.S. Federal Communications Commission (FCC). It consists of any jack that falls under Title 17, Part 68, Subpart F (section 68.502) of the FCC code. See also RJ11 and RJ45.

Registrant Name Change Agreement

see RNCA.

registrants

individuals or organizations who register a domain name and pay the appropriate fees for such registration.

Registrar

The service provider, approved by ICANN, who provides and handles the registration of a domain name for a fee. They may or may not provide other services that are necessary to launch or manage a website.

For a complete list of approved registrars go to http://www.icann.org/registrars/accredited-list.html.

Registration Grace Period

see RGP.

registry

1) the organization responsible for maintaining the domain name records associated with the DNS. The Registries are approved by ICANN thru order by the U.S. Department of Commerce.

2) the zone record that contains the official list of domains.

3) the office where the master registry records are kept showing all of the domain name registration records and registrants.

4) the official records or lists of the domain name holders or registrants

5) the location in MS Windows where information is stored concerning the hardware, software, operating system options, computer memory configurations, and startup programs.

relative addressing

is the process of addressing directories or webpages that are on the same host as the webpage being viewed.

Remote Data Service

See RDS.

remote hands

refers to physical hands of support personnel or of a MSP in a data center to physically reboot your web server, or provide other maintenance.

resolution

the end result of a process when a client attempts to connect to a host and queries the DNS server to obtain the required IP address. If a server of the local domain cannot return the address to the client, the client attempts to query another NS through iterative queries to obtain the IP address.

resolvability

the ability to resolve a domain name into an IP address. See also resolution and resolvers.

resolvers

the DNS client that processes the translation of domain names into IP addresses. A resolver receives a request from a user program and returns the requested information in the form compatible with the local host’s data format. See also resolution and resolvability.

Resource Records

also known as RR. Resource Records are records in the zone files of the DNS. They contain information related to the DNS for a given domain name on a host computer that describe that zone and all information for each domain name. The Resource Records contains the mapping information which maps the domain name to the IP address, as well as, other technical information about servers on the internet. The following resource records in a zone data file include the following types of information:

NAME    owner of RR, which is the associated NS

Type

Class    (i.e.  IN for Internet)

TTL    Time to Live

RDLength    a variable specifying the length of the RDATA

RDATA

A record

CNAME record

MX record

NS record

PTR record

SOA record

Other records containing information on hosts in the zone:

HINFO    Host Information

AFSDB    Andrew File System

X25,ISDN,RT    (various network information)

LOC    Location

SRV    Server Info

DNS & WIN    Windows record

TXT    Text files

WKS    Well Known Services

Responsible Person record

the Responsible Person record is a record that can be attached to any domain name and lists the person responsible for that host or zone. It consists of two parts, the electronic mail address portion in domain name format, and a domain name that must have a TXT file associated to it.

restricted TLD’s

see sponsored TLD’s.

reverse DNS

the method of returning a domain name from an IP address. Reverse DNS is part of the BIND DNS software that converts IP addresses into domain names. See the software tool lookup that provides for this functionality. Also known as inverse queries.

reverse domain hijacking

the term given, that first originated in the media, that describes when the holder of a mark for an entirely different classification of goods or services, claims right to a domain name registration of another party. Also referred to as reverse domain name hijacking.

reverse proxy cache

is a cache that is reverse-loaded automatically from a web server, rather than from a browser's client.

reverse proxy server

is a server located by the server side and receives requests from the client that is directed for the webserver. (The direction of web requests is reversed, incoming traffic versus outgoing traffic, as compared to a "forward" proxy server) Also, a reverse proxy server requires two mappings, a regular, to map to a server, and a reverse mapping, to redirect server requests to the reverse proxy server, thus giving to its' prefix, "reverse".

A reverse proxy server proxies on behalf of a web server versus a forward proxy server proxying on behalf of a client's browser.

The origin of the prefix "reverse" can come from one of the following:

1) direction of web traffic, inbound versus outbound.

2) location of the proxy.

3) the reverse mapping required in setup.

request

the process in the DNS that queries a server. A request can be either iterative, or recursive. See also query.

RFC

Requests for Comments, documents prepared that discuss the DNS elements concerning the operation and design of the Internet in detail. Jon Postel was the editor of the RFC’s for over 29 years, from its inception on April 7, 1969 to his untimely departure on Oct of 1998.

rgb

Red,Green,Blue, is the color attribute to describe the red, green, and blue values represented in decimal format from 0-255.  It would be written in the following format: color:rgb(0,255,0) or color:rgb(0%,100%,0%).  This would describe the color Green.

RGP

Registration Grace Period. A period of 30 calendar days after a domain name expires so an owner can renew the domain name before it is finally deleted from the registry and released back into the available pool of public domain names. The RGP was proposed by ICANN in 2002, and has been voluntarily adopted by the Registrars.

RIPE

Reseaux IP Europeans, is an organization which consists of European ISP’s. http://ripe.net

RIPE NCC

Reseaux IP Europeens Network Coordination Centre is the Regional Registry covering the European domains. http://www.ripe.net

RIR

Regional IP address Registries, see Regional Registries.

RJ

See Registered Jack.

RJ-11

Registerd Jack-11, is a six conductor jack. It is commonly used with telephone wires and is commonly implemented with a 2 pair wire, yielding 4 wires that are attached. Where one pair carries voice or data, and the other pair is used for low voltage signals for phone lights or other signaling.

RJ-14

Registered Jack-14, similar to the RJ-11, but configured with 2 pair wire, one pair each carrying voice or data.

RJ-45

Registered Jack-45, is a single line jack with eight pins for eight wires. RJ-45 is commonly used for 10Base-T or ethernet network connectivity in LAN's.

RNDC

Remote Name Daemon Controller, is a remote program that is used to control a local BIND 9 name server.

RPC

Remote Procedure Calls, are call methods of executing commands remotely using MS FrontPage.

RNCA

Registrant Name Change Agreement, is the method and agreement used when transferring a domain name from an owner to another registrant. This is what Network Solutions calls this method and agreement.

root

the highest level in hierarchy of the DNS that is unassigned. In the Unix filesystem it is represented by a “/”, and in the DNS system it is represented by a “.”.

root.cache

the root servers file, containing a list of authoritative root servers.

root name server

contains the resource records for all top-level-domain name servers. That is the root name servers know where all of the authoritative name servers are located for the TLD zones.

root name server operators

formerly Network Solutions, now Verisign Global Registry Services.

root server system

is a system of 13 Name Servers that comprise of the root server side of the DNS. The A server is maintained by Network Solutions, and contains the master list of the TLD name servers. THis list is replicated to 12 other root servers located around the world.

round-robin

a DNS process that systematically rotates the order of queried resources from a list of multiple A records assigned to a specific domain name to share the load on the requested host server. Note: round-robin is not load balancing, because it simply rotates the queries to the listed name servers, the name servers have no idea what the actual load is on the serving web-server.

Round Trip Time

see RTT.

routing tables

a map of the Internet (its connectivity), showing the layout of the backbones and associated data centers.

RR

see Resource Records.

RR format

the Resource Records format is in the following format: [owner][TTL][class][<type>>RDATA>

Each Resource Record maps to an A record. See Resource Records.

rs

registration services, is a subdomain of the InterNIC that provides DNS whois tools to lookup information on Name Servers, IP addresses, domain names and registrants. http://www.rs.internic.net/rs-internic.html

RSC

Root Server Confederations, a network of servers that service an alternate root zone, that is authoritative, but non-ICANN approved, for operational or commercial convenience or gain.

RSP

Registration Service Provider is the provider that registers domain names on behalf of clients with InterNIC, or the appropriate Registry responsible for maintaining domain registration records. An RSP resells the services of a Registrar to retail customers.

RSS

Root Server Systems, DNS systems set up on Alternate Authoritative Root Name Servers that are not endorsed or run by the ICANN Authoritative Root.

RT

Route Through Record Type, specifies an intermediate host that sends packets to a client. It is part of the DNS Resource Records. (experimental)

RTT

Round Trip Time, is:

1) a measurement of the amount of time it takes for a NS to respond to queries sent from a client. This measurement is made and recorded each time a NS is queried.

2) is a metric used by BIND name servers to determine which name servers are authoritative for a given zone.

rTLD

restricted TLD, see sTLD.

Run Book

A manual that documents common tasks a web hosting client will need to know concerning their website. (i.e. starting servers, performing backups, uploading content, obtaining secure access, how to access scripts, etc.)

RWHOIS

Referral WHOIS, is a directory services protocol for finding information on hosts, and network systems. Rwhois is an enhancement to the whois concept in a hierarchical and scaleable manner. http://www.rwhois.net