Second-level Domain
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Second-level Domain
In the Domain Name System (DNS) hierarchy, a second-level domain (SLD or 2LD) is a domain that is directly below a top-level domain (TLD). For example, in , is the second-level domain of the TLD. Second-level domains commonly refer to the organization that registered the domain name with a domain name registrar. Some domain name registries introduce a second-level hierarchy to a TLD that indicates the type of entity intended to register an SLD under it. For example, in the .uk namespace a college or other academic institution would register under the ccSLD, while companies would register under . Strictly speaking, domains like .ac.uk and .co.uk are second level domain themselves, since they are right below a TLD. A list of the official TLDs can be found at icann.org and iana.org. An ordinal-free term to denote domains under which people can register their own domain name is public suffix domain (PSD). Country-code second-level domains Algeria Australia Austria In ...
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Domain Name System
The Domain Name System (DNS) is a hierarchical and distributed naming system for computers, services, and other resources in the Internet or other Internet Protocol (IP) networks. It associates various information with domain names assigned to each of the associated entities. Most prominently, it translates readily memorized domain names to the numerical IP addresses needed for locating and identifying computer services and devices with the underlying network protocols. The Domain Name System has been an essential component of the functionality of the Internet since 1985. The Domain Name System delegates the responsibility of assigning domain names and mapping those names to Internet resources by designating authoritative name servers for each domain. Network administrators may delegate authority over sub-domains of their allocated name space to other name servers. This mechanism provides distributed and fault tolerance, fault-tolerant service and was designed to avoid a single ...
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Top-level Domain
A top-level domain (TLD) is one of the domains at the highest level in the hierarchical Domain Name System of the Internet after the root domain. The top-level domain names are installed in the root zone of the name space. For all domains in lower levels, it is the last part of the domain name, that is, the last non empty label of a fully qualified domain name. For example, in the domain name www.example.com, the top-level domain is .com. Responsibility for management of most top-level domains is delegated to specific organizations by the ICANN, an Internet multi-stakeholder community, which operates the Internet Assigned Numbers Authority (IANA), and is in charge of maintaining the DNS root zone. History Originally, the top-level domain space was organized into three main groups: ''Countries'', ''Categories'', and ''Multiorganizations''. An additional ''temporary'' group consisted of only the initial DNS domain, arpa, and was intended for transitional purposes toward the ...
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Domain Name Registrar
A domain name registrar is a company that manages the reservation of Internet domain names. A domain name registrar must be accredited by a generic top-level domain (gTLD) registry or a country code top-level domain (ccTLD) registry. A registrar operates in accordance with the guidelines of the designated domain name registries. History Until 1999, Network Solutions Inc. (NSI) operated the registries for the ''com'', ''net'', and ''org'' top-level domains (TLDs). In addition to the function of domain name registry operator, it was also the sole registrar for these domains. However, several companies had developed independent registrar services. In 1996 one such company, Ivan Pope's company, NetNames, developed the concept of a standalone commercial domain name registration service which would sell domain registration and other associated services to the public, effectively establishing the retail arm of an industry with the registries being the wholesalers. NSI assimilated ...
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Domain Name Registry
A domain name registry is a database of all domain names and the associated registrant information in the top level domains of the Domain Name System (DNS) of the Internet that enables third party entities to request administrative control of a domain name. Most registries operate on the top-level and second-level of the DNS. A registry operator, sometimes called a network information center (NIC), maintains all administrative data of the domain and generates a zone file which contains the addresses of the nameservers for each domain. Each registry is an organization that manages the registration of domain names within the domains for which it is responsible, controls the policies of domain name allocation, and technically operates its domain. It may also fulfill the function of a domain name registrar, or may delegate that function to other entities. Domain names are managed under a hierarchy headed by the Internet Assigned Numbers Authority (IANA), which manages the top of the D ...
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CcSLD
A country code second-level domain is a second-level domain to a country code top-level domain. Such a domain may be reserved by a domain name registry for the registration of third-level domains, or assigned to a third party as a subdomain. Many country code domain registries implement domain name classes at the second level underneath their ccTLD, such as are present in the original generic top-level domains , , and , which were intended for commercial entities, network operators, and non-profit organizations, respectively. Many countries implement additional classes. For example, the United Kingdom (.uk) uses for commercial purposes and for academic registrants. Brazil (.br) has a high number of predefined second-level domains, 140 as of 2021; they range from for commercial activities and for veterinarians to for wikis (see .br § Second-level domains). See also * Domain Name System The Domain Name System (DNS) is a hierarchical and distributed naming system for c ...
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Cybersquatting
Cybersquatting (also known as domain squatting) is the practice of registering, trafficking in, or using an Internet domain name, with a bad faith intent to profit from the goodwill of a trademark belonging to someone else. The term is derived from " squatting", which is the act of occupying an abandoned or unoccupied space or building that the squatter does not own, rent, or otherwise have permission to use. Terminology In popular terms, “cybersquatting” is the term most frequently used to describe the deliberate, bad faith abusive registration of a domain name in violation of trademark rights. However, precisely because of its popular currency, the term has different meanings to different people. Some people, for example, include “warehousing,” or the practice of registering a collection of domain names corresponding to trademarks with the intention of selling the registrations to the owners of the trademarks, within the notion of cybersquatting, while others distingui ...
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Single-letter Second-level Domains
Single-letter second-level domains are domains in which the second-level domain of the domain name consists of only one letter, such as x.com. In 1993, the Internet Assigned Numbers Authority (IANA) explicitly reserved all single-letter and single-digit second-level domains under the top-level domains com, net, and org, and grandfathered those that had already been assigned. In December 2005, ICANN considered auctioning these domain names. Active single-letter domains On December 1, 1993, the Internet Assigned Numbers Authority (IANA) explicitly reserved the remaining single-letter and single-digit domain names. The few domains that were already assigned were grandfathered in and continued to exist. The six single-letter domains in existence at that time under .com, .net and .org were the following: The .org TLD was subsequently reopened for single-letter domain registrations. These and selected other gTLD and ccTLD single-letter domain names currently in use, typically as sho ...
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Top-level Domain
A top-level domain (TLD) is one of the domains at the highest level in the hierarchical Domain Name System of the Internet after the root domain. The top-level domain names are installed in the root zone of the name space. For all domains in lower levels, it is the last part of the domain name, that is, the last non empty label of a fully qualified domain name. For example, in the domain name www.example.com, the top-level domain is .com. Responsibility for management of most top-level domains is delegated to specific organizations by the ICANN, an Internet multi-stakeholder community, which operates the Internet Assigned Numbers Authority (IANA), and is in charge of maintaining the DNS root zone. History Originally, the top-level domain space was organized into three main groups: ''Countries'', ''Categories'', and ''Multiorganizations''. An additional ''temporary'' group consisted of only the initial DNS domain, arpa, and was intended for transitional purposes toward the ...
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Country Code Top-level Domain
A country code top-level domain (ccTLD) is an Internet top-level domain generally used or reserved for a country, sovereign state, or dependent territory identified with a country code. All ASCII ccTLD identifiers are two letters long, and all two-letter top-level domains are ccTLDs. In 2018, the Internet Assigned Numbers Authority (IANA) began implementing internationalized country code top-level domains, consisting of language-native characters when displayed in an end-user application. Creation and delegation of ccTLDs is described in RFC 1591, corresponding to ISO 3166-1 alpha-2 country codes. While gTLDs have to obey international regulations, ccTLDs are subjected to requirements that are determined by each country’s domain name regulation corporation. With over 150 million domain name registrations today or as of 2022, ccTLDs make up about 40% of the total domain name industry. Country code extension applications began in 1985. The registered country code extensions in t ...
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Subdomain
In the Domain Name System (DNS) hierarchy, a subdomain is a domain that is a part of another (main) domain. For example, if a domain offered an online store as part of their website example.com, it might use the subdomain shop.example.com . Overview The Domain Name System (DNS) has a tree structure or hierarchy, which includes nodes on the tree being a domain name. A subdomain is a domain that is part of a larger domain. Each label may contain from 1 to 63 octets. The full domain name may not exceed a total length of 253 ASCII characters in its textual representation.RFC 1035, ''Domain names--Implementation and specification'', P. Mockapetris (Nov 1987) Subdomains are defined by editing the DNS zone file pertaining to the parent domain. However, there is an ongoing debate over the use of the term "subdomain" when referring to names which map to the Address record A (host) and various other types of zone records which may map to any public IP address destination and any type ...
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Private Sub-domain Registry
A private sub-domain registry allocates domain names in a subset of the Domain Name System under a domain registered with an ICANN-accredited or ccTLD registry. Most of the private sub-domain registries operate based on an ISO 3166-1 name that is a subdomain of a higher-level domain. Some of these registries combine the domain registry and the domain registrar functions in the administration structure, while others distribute domains via third-party registrars. Operation Private registries operate at a technical level identical to official domain registries using the well-known principles of operation of the Domain Name System. In addition, the registries may also operate a WHOIS service to publish domain name information. History The idea for an independent global domain name registry stems from a series of conversations between one of CentralNic's original founders and the late Jon Postel, one of the founding fathers of the modern Internet. Postel suggested the use of ''.UK. ...
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Public Suffix List
The Public Suffix List (PSL) is a catalog of certain Internet domain names. Entries on the list are also referred to as effective top-level domains (eTLD). The Mozilla Foundation initiated the suffix list for the security and privacy policies of its Firefox web browser, but it is widely applied, with varying success, to a variety of other purposes under the Mozilla Public License (MPL). List The list is used by Mozilla browsers (Firefox), by Google in Chrome and Chromium projects on certain platforms, and by Opera. According to Mozilla, While ''com'', ''uk'', and ''us'' are top-level domains (TLDs), Internet users cannot always register the next level of domain, such as "co.uk" or "wy.us", because these may be controlled by domain registrars. By contrast, users can register second level domains within ''com'', such as ''example.com'', because registrars control only the top level. The Public Suffix List is intended to enumerate all domain suffixes controlled by registrars. An i ...
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