Reference & Manual > Glossary > R

RAID
Redundant Array of Independent (or Inexpensive) Disks. Type of disk, often used on servers, where several physical disks are combined into an array for better speed and fault tolerance.
Level 0 implements data striping where file blocks are written to separate drives. Does not provide fault tolerance, because failure of one drive will result in data loss.
Level 1 implements data mirroring. Data is duplicated on two drives either through software or hardware. Provides faster read performance than a single drive.
Level 2 - not used in practice. Data is split at bit level at written to multiple drives.
Level 3 - requires at least 3 drives. Data block is striped at byte level across drives and error correction codes (parity info) is recorder on another drive. Provides fault tolerance but slower writing performance.
Level 4 - Similar to Level 3 but provides faster performance because it uses blocks for striping.
Level 5 - Similar to Level 4 but improves performance but also striping parity info across multiple drives.
Level 6 - Similar to Level 5 but also uses second parity scheme for better fault tolerance.
Level 7 - Proprietary RAID design by Storage Computer Corporation. Faster than other levels because it uses multiple levels of cache and asynchronous I/O transfers.
In addition multiple RAID levels can be combined to improve performance or reliability.

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.

Real Audio and Video
Real Audio and Video is a client-server software system and file format(s) by Real Networks that allows Internet users to play audio and/or video-based multimedia content in real time as they are being downloaded (called "streaming media"), instead of the user having to download the complete file before being able to play it.

Real-Time Credit Card Transaction Processing
Includes the establishment of Internet merchant accounts, and provides the ability to immediately accept and process credit cards online including authorization and daily online settlements.

Reciprocal Links
A reciprocal link is where a text or banner link on one website [A] points to another (external) website [B], which in turn displays a text or banner link pointing back to website [A].

Register (Domain Name)
Since every domain is unique, registries have been set up to assign domains to individuals and organizations. When a domain is registered with the appropriate registry, that domain is assigned and becomes no longer available for anyone else to use. Typically, there are registration and renewal fees (local registry fees) associated with the right to use a domain. However, there are some TLDs that are provided at no charge.

Registrant (Domain Name)
The entity, organization or individual that will be using the domain name.

Registrar (Domain Name)
Some registries don't provide the ability for end users to register domains with them directly. They might require end users to purchase the domain through an internet provider that is acting as the registrar.

Registry (Domain Name)
An organization responsible for assigning domain names for the TLD that they manage. Furthermore, it is their responsibility to update the global DNS tables that all nameservers use to resolve domain names. For example, InterNIC is the registry for .COM, .NET and .ORG domain names.

Remote Access
When you access a computer that you are unable to see. This is done via a modem or computer network.

Renewal (Domain Name)
Most TLDs need to be renewed at some scheduled yearly interval. This is an opportunity for both the registrant and the registry to update their records as well as collect any applicable renewal fees.

Reseller Hosting
Arrangement whereby a company selling hosting to consumers uses the datacenter and equipment of another company.

Resolution (domain Name)
The conversion of an internet address or domain name into the corresponding physical location.

Resolve
The term used to describe the process by which domain names are matched with corresponding Internet Protocol (IP) numbers. "Resolution" is accomplished by a combination of computers and software, which use the data in the Domain Name System to determine which IP numbers correspond to a particular domain name. Basically, it is translating a number to the name you see in your browser for the web site you are visiting.

RFC
(Request For Comments) -- The name of the result and the process for creating a standard on the Internet . New standards are proposed and published on line, as a Request For Comments. The Internet Engineering Task Force is a consensus-building body that facilitates discussion, and eventually a new standard is established, but the reference number/name for the standard retains the acronym RFC, e.g. the official standard for e-mail is RFC 822.

RJ-11
A standard connector that is used to connect to the telephone line. Also known as a phone jack.

RJ-45
A standard connector that is used to connect to the Ethernet network. Looks like a big phone jack.

ROFL
Rolling On the Floor Laughing

Router
A device that connects two Local Area Networks. Routers are similar to bridges, but provide additional functionality, such as the ability to filter messages and forward them to different places based on various criteria. The Internet uses routers extensively to forward packets from one host to another.

Robot / Crawler / Spider
A spider is a program run by a search engine to build a summary of a website's content (content index). It creates a text-based summary of content and an address (URL) for each webpage.

When a user searches, the keyword(s) they enter are compared with the available website content indexes. Due to the large number of web pages indexed, direct text-only-matching is rare, rather search engines use sophisticated logics (algorithms) to rank potential matches. For example, the underlying information hierarchy of a webpage (semantic markup) may be factored into the ranking a webpage is assigned.

Robots File / Robots.txt
A robots.txt is a permissions file that can be used to control which web pages of a website a search engine indexes. The file must be located in the root directory of the website for a search engine website-indexing program (spider) to reference, i.e. if the website address is:

www.yoursite.co.nz

Then the robots.txt file must be located at: www.yoursite.co.nz/robots.txt
The robots.txt file contains instructions ( directives ) that are read by spiders. Directives can be written to apply to all spiders or only target spiders from a specific search engine.

Root Server
A machine that has the software and data needed to locate name servers that contain authoritative data for the top-level domains.

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.