Information about Subdomain
For a protein domain inside of a larger domain, see .
In the Domain Name System (DNS) hierarchy, a subdomain is a domain that is part of a larger domain. For example, "example.com" is a subdomain of the "com" top-level domain (TLD) while "www.example.com" is a service in the domain "example.com". In fact, the "com" TLD is a subdomain of the root domain, ".". This hierarchical organisation is similar to that in a filesystem; something is a subdomain if it could be equated to a folder, and a record within that subdomain to a file. Note, though, that DNS names are written in descending hierarchy right-to-left, where filesystems are written left-to-right.
Relative to a subdomain, the larger domain that it is a part of is its parent domain, or alternately superdomain (the former term appears to be preferred by the IETF).
Note that "subdomain" expresses relative dependence, not absolute dependence: for example, wikipedia.org comprises a subdomain of the org domain, and en.wikipedia.org comprises a subdomain of the domain wikipedia.org. In theory, this subdivision can go down to 127 levels deep, and each label can contain up to 63 characters, as long as the whole domain name does not exceed a total length of 255 characters. But in practice some domain registries have shorter limits than that.
A subdomain is sometimes termed a vanity domain, especially when it is a subdomain of an ISP's own domain aliased to an individual user account. However, the term "vanity domain" has other usages, discussed at that article.
Some websites use a different Host name to point to different servers in a clusters. For example, www.example.com points to Server Cluster 1 or Datacentre 1, and www2.example.com points to Server Cluster 2 or Datacentre 2, etc.
Subdomains are commonly used by organizations that wish to assign a unique name to a particular department, function, or service related to the organization. For example, a university might assign "cs" to the computer science department, such that a number of hosts could be used inside that subdomain, such as mail.cs.example.edu or www.cs.example.edu.
Depending on application, a record inside a domain, or subdomain might refer to a Host name, or a service provided by a number of machines in a cluster.
See also
On the Internet, the Domain Name System (DNS) associates various sorts of information with so-called domain names; most importantly, it serves as the "phone book" for the Internet by translating human-readable computer hostnames, e.g. en.wikipedia.
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domain name has multiple related meanings:
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- A name that identifies a computer or computers on the internet. These names appear as a component of a Web site's URL, e.g. wikipedia.org. This type of domain name is also called a hostname.
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top-level domain (TLD) is the last part of an Internet domain name; that is, the letters which follow the final dot of any domain name. For example, in the domain name www.example.
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root name server is a DNS server that answers requests for the root namespace domain, and redirects requests for a particular top-level domain (TLD) to that TLD's nameservers.
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file system (often also written as filesystem) is a method for storing and organizing computer files and the data they contain to make it easy to find and access them.
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A domain name registry, also called Network Information Centre (NIC), is part of the Domain Name System (DNS) of the Internet which converts domain names to IP addresses.
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In the Domain Name System (DNS), a vanity domain is a domain name, often a subdomain, whose purpose is to express the individuality of the person on whose behalf it is registered. This contrasts with domain names which resolve to an organisation (e.g.
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A hostname (occasionally also, a sitename) is the unique name by which a network-attached device (which could consist of a computer, file server, network storage device, fax machine, copier, cable modem, etc.) is known on a network.
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A hostname (occasionally also, a sitename) is the unique name by which a network-attached device (which could consist of a computer, file server, network storage device, fax machine, copier, cable modem, etc.) is known on a network.
..... Click the link for more information.
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domain name has multiple related meanings:
..... Click the link for more information.
- A name that identifies a computer or computers on the internet. These names appear as a component of a Web site's URL, e.g. wikipedia.org. This type of domain name is also called a hostname.
..... Click the link for more information.
A hostname (occasionally also, a sitename) is the unique name by which a network-attached device (which could consist of a computer, file server, network storage device, fax machine, copier, cable modem, etc.) is known on a network.
..... Click the link for more information.
..... Click the link for more information.
On the Internet, the Domain Name System (DNS) associates various sorts of information with so-called domain names; most importantly, it serves as the "phone book" for the Internet by translating human-readable computer hostnames, e.g. en.wikipedia.
..... Click the link for more information.
..... Click the link for more information.
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