Fully qualified domain name

A fully qualified domain name (FQDN), sometimes also referred to as an absolute domain name, is a domain name that specifies its exact location in the tree hierarchy of the Domain Name System (DNS). It specifies all domain levels, including the top-level domain and the root zone. A fully qualified domain name is distinguished by its lack of ambiguity: it can be interpreted only in one way.

The DNS root domain is unnamed, which is expressed by the empty label, resulting in a fully qualified domain name ending with the full stop (period) character.

In contrast to a domain name that is fully specified, a domain name that does not include the full path of labels up to the DNS root, is often called a partially qualified domain name.

Syntax

A fully qualified domain name consists of a list of domain labels representing the hierarchy from the lowest relevant level in the DNS to the top-level domain (TLD). The domain labels are concatenated using the full stop (dot, period) character as separator between labels.

Fully qualified name

In computer programming, a fully qualified name is an unambiguous name that specifies which object, function, or variable a call refers to without regard to the context of the call. In a hierarchical structure, a name is fully qualified when it "is complete in the sense that it includes (a) all names in the hierarchic sequence above the given element and (b) the name of the given element itself."

Programming

In computer programming, a fully qualified name is an unambiguous name that specifies which object, function, or variable a call refers to without regard to the context of the call. In a hierarchical structure, a name is fully qualified when it "is complete in the sense that it includes (a) all names in the hierarchic sequence above the given element and (b) the name of the given element itself." Thus fully qualified names explicitly refer to namespaces that would otherwise be implicit because of the scope of the call. While always done to eliminate ambiguity, this can mean different things dependent on context.

Domain name

A domain name is an identification string that defines a realm of administrative autonomy, authority or control within the Internet. Domain names are formed by the rules and procedures of the Domain Name System (DNS). Any name registered in the DNS is a domain name. Domain names can also be thought of as a location where certain information or activities can be found.

Domain names are used in various networking contexts and application-specific naming and addressing purposes. In general, a domain name represents an Internet Protocol (IP) resource, such as a personal computer used to access the Internet, a server computer hosting a web site, or the web site itself or any other service communicated via the Internet. In 2014, the number of active domains reached 271 million.

Domain names are organized in subordinate levels (subdomains) of the DNS root domain, which is nameless. The first-level set of domain names are the top-level domains (TLDs), including the generic top-level domains (gTLDs), such as the prominent domains com, info, net, edu, and org, and the country code top-level domains (ccTLDs). Below these top-level domains in the DNS hierarchy are the second-level and third-level domain names that are typically open for reservation by end-users who wish to connect local area networks to the Internet, create other publicly accessible Internet resources or run web sites. The registration of these domain names is usually administered by domain name registrars who sell their services to the public.