Rack server
Web servers that are stored in rack formations. Usually between 1U and 4U configurations depending on the capacity of the server and number of processors.

RAID
Short for Redundant Array of Independent Disks, a method of data protection/backup. Data is stored over a number of servers so that information will still be accessible if a piece of hardware/software crashes.

RAM - Random Access Memory
The most common computer memory which can be used by programs to perform necessary tasks while the computer is on; an integrated circuit memory chip allows information to be stored or accessed in any order and all storage locations are equally accessible.

Ranking
In search engines - this is the order in which your site would pull up under a query on the search database. Your ranking can be improved by some search engine optimization techniques.

Raw access
Ability to telnet or ssh to a server (rare in shared hosting).

Raw Logs
Raw access data updated in real-time that can be downloaded and used by any statistics program. Typically each line show the user's IP, date and time of the access, what kind of request was done, which document was requested, HTTP status code, bytes transferred, referrer, and user agent info. If a host doesn't have statistics, you'll need access to raw logs to identify who your site's visitors are. Analyzing raw logs can also provide more detailed look at site accesses than stats.

RDBMS - Relational Data Base Management Systems
(RDBMS) are database management systems that maintain data records and indices in tables. Relationships may be created and maintained across and among the data and tables.

Real audio
Software that allows sound files to be transmitted from the Internet back to the user’s PC in streams. What actually happens is that the file starts playing (i.e. you hear the music) before all of the data has been received - giving the effect of playing the sound instantaneously.

Record
DNS configuration record, such as SOA, NS, A, CNAME, HINFO, WKS, MX and PTR that comprises the data within a DNS zone.

Record Class
There are three schemes for record systems, Internet, Hesiod, and Chaos. Internet is by far the most common. The others are almost extinct.

Recursive Query
A recursive query is a request from a host to a resolver to find data on other name servers.

Redemption period
A period of time after domain registration has expired where the previous owner can bring the registration current by paying applicable fees to the registrar. There is a min. redemption period, but some registrars differ.

Redirect
Transfering a web user to a different domain than they specified. Example : User types in to address bar of brower - http://www.THISDOMAIN.com - But then the actual url viewed may actually be called - http://www.THATDOMAIN.com.

Redundant
The exact same data stored in more than one location in the same hard drive or database. Unnecessary redundancy can cause problems if one copy of the data is updated and another copy of the data is not. All redundant data can’t be eliminated in most databases because primary keys in one table are repeated in other tables as foreign keys to create links between tables. This type of redundancy is called controlled redundancy. Also - web hosting companies use power and bandwidth redundancy to ensure uptime.

Referrers
The URL of the web page from which a visitor came. The server's referrer log file will indicate this. If a visitor came directly from a search engine listing, the query used to find the page will usually be encoded in the referer URL, making it easy to see which keywords are bringing visitors. The referer information can also be accessed as document.referrer within JavaScript or via the HTTP_REFERER environment variable (accessible from scripting languages).

Refresh Field
Fourth field in an SOA record. Refresh determines the number of seconds between a successful check on the serial number on the zone of the primary, and the next attempt. Usually around 2-24 hours. Not used by a primary server.

Registrar
A registrar provides direct services to domain name registrants. The registrar database contains customer information in addition to the DNS information contained in the Registry database. Registrars process name registrations for Internet end-users and then send the necessary DNS information to a Registry for entry into the centralized Registry database and ultimate propagation over the Internet. There are multiple registrars providing registration services through the NSI Registry.

Registration
Process of obtaining / reserving a domain name for personal or business use. Upon registration an individual must specify an Admin Contact, Technical Contact, and Billing Contact. The Admin Contact is the primary method used for transfers, confirmations, etc.

Registry
An Internet domain name registry is an entity that receives domain name service (DNS) information from domain name registrars, inserts that information into a centralized database and propagates the information in Internet zone files on the Internet so that domain names can be found by users around the world via applications such as the world wide web and email. VeriSign Global Registry Services is the exclusive registry for the .com, .net and .org top level domains. Other domain extensions have other central registries.

Relational Database
relational database management system (RDBMS) organizes data into related rows and columns as specified by the relational model. Microsoft SQL Server and Oracle are examples of relational database management systems. A Microsoft Access database is an example of a relational database.

Renewal
Keeping a domain name registration current. Each year you must renew your domain name with your registrar (unless you prepaid for multiple years).

Reseller
Resellers are usually smaller companies that still try to build their customers base. They don't own the server with user accounts but can perform most administrative functions.

Reseller Web Hosting
A reseller operates components of a Web hosting operation using services, infrastructure and equipment provided by another Web hosting service. Some resellers operate full-fledged businesses using the hardware, software, network and logistical support of another Web hosting firm, while others simply operate as sales agents for other Web hosting companies, offering discounts and providing low-level technical support.

Resolution
The fineness of detail attained by a printer or a monitor in producing an image. For printers that form characters from small, closely spaced dots, resolution is measured in dots per inch, or dpi, and ranges from about 125 dpi for low–quality dot–matrix printers to about 600 dpi for some laser and ink–jet printers (typesetting equipment can print at resolutions of over 1000 dpi). For a video display, the number of pixels is determined by the graphics mode and video adapter, but the size of the display depends on the size and adjustment of the monitor; hence the resolution of a video display is taken as the total number of pixels displayed horizontally and vertically. See also high resolution, low resolution. 2. The process of translation between a domain name address and an IP address.

Resolver
Client part of the DNS client/server mechanism. A resolver creates queries sent across a network to a name server, interprets responses, and returns information to the requesting programs.

Resource Record
DNS configuration record, such as SOA, NS, A, CNAME, HINFO, WKS, MX and PTR that comprises the data within a DNS zone.

Retry Field
Fifth field in an SOA record. If a refresh attempt fails, a server will retry this after many seconds. Not used by a primary server.

Reverse Domain
Same as Reverse Zone : A reverse zone is a zone whose purpose is the mapping of IP addresses to names. Nearly all reverse zones are descended from the IN-ADDR.ARPA zone.

Reverse Record
Pointer Record. Also called a reverse record. A PTR record associates an IP address with a canonical name. PTR records should point to a name that can be resolved back to the IP address. The name of the pointer record is not the IP address itself, but is the IP address’ four IP octets in reverse order followed by IN-ADDR.ARPA.

Reverse Zone
A reverse zone is a zone whose purpose is the mapping of IP addresses to names. Nearly all reverse zones are descended from the IN-ADDR.ARPA zone.

RJ-11
A standard connector that is used to connect to the telephone line.

RJ-45
A standard connector that is used to connect to the Ethernet network.

Rollovers
A script such as java can do an image swap or text feature on a mouse over, or rollover.

Root Server
A machine that has the software and data needed to locate name servers that contain authoritative data for the top-level domains (e.g., root servers know which name servers contain authoritative data for com, net, ch, uk, etc.). The root servers are, in fact, name servers and contain authoritative data for the very top of the Domain Name System (DNS) hierarchy. Currently, technical specifications limit the number of root servers to 13. These machines are currently located around the globe, in the U.S., the U.K., Sweden, and Japan.

Root Zone
The ancestor of all zones, the parent of the top level domains.

Round Robin Load Sharing
Old style of a load sharing system without any fault tolerance. A native feature of most major servers; If multiple resource records of the same name and type are found, all will be sent; However, their order will be rotated for successive queries. For example, identical A records could point to different IP Addresses. This works for load sharing because web browsers and other clients usually only expect only one record of the appropriate type in response, and ignore further records after the first. Can cause problems with PTR records, causing mail delivery problems because IPs might not resolve back to the name expected.

Router
A network device (can be a dedicated computer) that is used to connect two or more networks together and route packets between them.

RP Record
A Responsible Person Record is informational, not functional. Used to indicate the person responsible for the domain name.

RSA
A public key cryptosystem developed by Ron Rivest, Adi Shamir, and Leonard Adleman. It can be used to encrypt session keys and to generate digital certificates.