A fully qualified domain name (or FQDN) is an unambiguous domain name that specifies the node's position in the DNS tree hierarchy absolutely. To distinguish an FQDN from a regular domain name, a trailing period is added. ex: somehost.example.com. An FQDN differs from a regular domain name by its absoluteness; a suffix will not be added.
For example, given a device with a hostname of "myhost" and a domain name of "example.com", the fully qualified domain name is "myhost.example.com.". It therefore uniquely defines the device — whilst there might be many hosts in the world called "myhost", there can only be one "myhost.example.com.".
Notice that there is a dot at the very end of the domain name, i.e. it ends ".com." and not ".com" — this indicates that the name is an FQDN. For example "myhost.bar.com" could be ambiguous, because it could be the prefix of a longer domain name such as "myhost.bar.com.au", whereas "myhost.bar.com." is a fully qualified domain name. Technically, the dot comes before the empty label indicating the root of the Domain Name System hierarchy, and so an FQDN is sometimes called a rooted domain name. In practice, the dot is almost always omitted in everyday applications, making such domain references technically ambiguous.
The maximum permitted length of an FQDN is 255 bytes, with an additional restriction to 63 bytes for each label within the domain name. The syntax of domain names is discussed in various RFCs — RFC 1035, RFC 1123 and RFC 2181. Any binary string can be used as the label of any resource record; a common misconception is that names are limited to a subset of ASCII characters.
Internationalized domain names expand the character repertoire of domain names to include non-ASCII characters, by encoding Unicode characters into byte strings within the normal FQDN character set. As a result, the character length limits of internationalized domain names are content-dependent.
Monday, November 26, 2007
DOMAIN TASTING
Domain tasting, also known as domain kiting, is a practice of registrants using the five-day "grace period" at the beginning of a domain registration for ICANN-regulated generic top-level domains to test the marketability of a domain name. During this period, when a registration must be fully refunded by the domain registry, a cost-benefit analysis is conducted by the registrant on the viability of deriving income from advertisements being placed on the domain's web site.
Domains that are deemed "successes" and retained in registrant's portfolio often represent domains that were previously used and have since expired, misspellings of other popular sites, or generic terms that may receive type-in traffic. These domains are usually still active in search engines and other hyperlinks and therefore derive enough traffic such that advertising revenue exceed the cost of the registration. The registrant may also derive revenue from eventual sale of the domain, at a premium, to a third party.
ControversyThe practice is controversial as practitioners typically register many hundreds of thousands of domain names under this practice, with these temporary registrations far exceeding the number of domain names actually licensed.
In April 2006, out of 35 million registrations, only a little more than 2 million were permanent or actually purchased. By February 2007, the CEO of GoDaddy reported that of 55.1 million domain names registered, 51.5 million were canceled and refunded just before the 5 day grace period expired and only 3.6 million domain names were actually kept.
Some claim domain name registries such as VeriSign and the Public Interest Registry have turned a blind eye to the practice as it has dramatically increased the number of registrations secured and renewed. However, this claim is inconsistent with proposals by registries to introduce measures that would reduce or eliminate the practice.
Domains that are deemed "successes" and retained in registrant's portfolio often represent domains that were previously used and have since expired, misspellings of other popular sites, or generic terms that may receive type-in traffic. These domains are usually still active in search engines and other hyperlinks and therefore derive enough traffic such that advertising revenue exceed the cost of the registration. The registrant may also derive revenue from eventual sale of the domain, at a premium, to a third party.
ControversyThe practice is controversial as practitioners typically register many hundreds of thousands of domain names under this practice, with these temporary registrations far exceeding the number of domain names actually licensed.
In April 2006, out of 35 million registrations, only a little more than 2 million were permanent or actually purchased. By February 2007, the CEO of GoDaddy reported that of 55.1 million domain names registered, 51.5 million were canceled and refunded just before the 5 day grace period expired and only 3.6 million domain names were actually kept.
Some claim domain name registries such as VeriSign and the Public Interest Registry have turned a blind eye to the practice as it has dramatically increased the number of registrations secured and renewed. However, this claim is inconsistent with proposals by registries to introduce measures that would reduce or eliminate the practice.
Monday, November 19, 2007
Uses and abuses
As domain names became attractive to marketers, rather than just the technical audience for which they were originally intended, they began to be used in manners that in many cases did not fit in their intended structure. As originally planned, the structure of domain names followed a strict hierarchy in which the top level domain indicated the type of organization (commercial, governmental, etc.), and addresses would be nested down to third, fourth, or further levels to express complex structures, where, for instance, branches, departments, and subsidiaries of a parent organization would have addresses which were subdomains of the parent domain. Also, hostnames were intended to correspond to actual physical machines on the network, generally with only one name per machine.
However, once the World Wide Web became popular, site operators frequently wished to have memorable addresses, regardless of whether they fit properly in the structure; thus, since the .com domain was the most popular and memorable, even noncommercial sites would often get addresses under it, and sites of all sorts wished to have second-level domain registrations even if they were parts of a larger entity where a logical subdomain would have made sense (e.g., abcnews.com instead of news.abc.com). A Web site found at http://www.example.org/ will often be advertised without the "http://", and in most cases can be reached by just entering "example.org" into a Web browser. In the case of a .com, the Web site can sometimes be reached by just entering "example" (depending on browser versions and configuration settings, which vary in how they interpret incomplete addresses).
The popularity of domain names also led to uses which were regarded as abusive by established companies with trademark rights; this was known as cybersquatting, in which somebody took a name that resembled a trademark in order to profit from traffic to that address. To combat this, various laws and policies were enacted to allow abusive registrations to be forcibly transferred, but these were sometimes themselves abused by overzealous companies committing reverse domain hijacking against domain users who had legitimate grounds to hold their names, such as their being generic words as well as trademarks in a particular context, or their use in the context of fan or protest sites with free speech rights of their own.
Laws that specifically address domain name conflicts include the Anticybersquatting Consumer Protection Act in the United States and the Trademarks Act, 1999, in India. Alternatively, domain registrants are bound by contract under the UDRP to comply with mandatory arbitration proceedings should someone challenge their ownership of the domain name.
However, once the World Wide Web became popular, site operators frequently wished to have memorable addresses, regardless of whether they fit properly in the structure; thus, since the .com domain was the most popular and memorable, even noncommercial sites would often get addresses under it, and sites of all sorts wished to have second-level domain registrations even if they were parts of a larger entity where a logical subdomain would have made sense (e.g., abcnews.com instead of news.abc.com). A Web site found at http://www.example.org/ will often be advertised without the "http://", and in most cases can be reached by just entering "example.org" into a Web browser. In the case of a .com, the Web site can sometimes be reached by just entering "example" (depending on browser versions and configuration settings, which vary in how they interpret incomplete addresses).
The popularity of domain names also led to uses which were regarded as abusive by established companies with trademark rights; this was known as cybersquatting, in which somebody took a name that resembled a trademark in order to profit from traffic to that address. To combat this, various laws and policies were enacted to allow abusive registrations to be forcibly transferred, but these were sometimes themselves abused by overzealous companies committing reverse domain hijacking against domain users who had legitimate grounds to hold their names, such as their being generic words as well as trademarks in a particular context, or their use in the context of fan or protest sites with free speech rights of their own.
Laws that specifically address domain name conflicts include the Anticybersquatting Consumer Protection Act in the United States and the Trademarks Act, 1999, in India. Alternatively, domain registrants are bound by contract under the UDRP to comply with mandatory arbitration proceedings should someone challenge their ownership of the domain name.
Top-level domains
Every domain name ends in a top-level domain (TLD) name, which is always either one of a small list of generic names (three or more characters), or a two-character territory code based on ISO-3166 (there are few exceptions and new codes are integrated case by case). Top-level domains are sometimes also called first-level domains.The generic top-level domain (gTLD) extensions are:In addition to the top-level domains, there are second-level domain (SLD) names. These are the names directly to the left of .com, .net, and the other top-level domains. As an example, in the domain en.wikipedia.org, "wikipedia" is the second-level domain.On the next level are third-level domains. These domains are immediately to the left of a second-level domain. In the en.wikipedia.org example, "en" is a third-level domain. There can be fourth and fifth level domains and so on, with virtually no limitation. An example of a working domain with five levels is www.sos.state.oh.us. Each level is separated by a dot or period symbol between them.Domains of third or higher level are also known as subdomains, though this term technically applies to a domain of any level, since even a top-level domain is a "subdomain" of the "root" domain (a "zeroth-level" domain that is designated by a dot alone).Traditionally, the second level domain has been chosen based on the name of a company (i.e. microsoft.com). The third level was commonly used to designate a particular host server. Therefore, ftp.wikipedia.org might be an FTP server, www.wikipedia.org would be a World Wide Web Server, and mail.wikipedia.org could be an email server. Modern technology now allows multiple servers to serve a single subdomain, or multiple protocols or domains to be served by a single computer. Therefore, subdomains may or may not have any real purpose.
DOMAIN NAME
The term domain name has multiple related meanings:
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. The product that domain name registrars provide to their customers. These names are often called registered domain names. Names used for other purposes in the Domain Name System (DNS), for example the special name which follows the @ sign in an email address, or the Top-level domain names like .com, or the names used by the Session Initiation Protocol (VoIP), or DomainKeys. They are sometimes colloquially (and incorrectly) referred to by marketers as "web addresses". This article will primarily discuss registered domain names. See the Domain Name System article for technical discussions about general domain names and the hostname article for further information about the most common type of domain name.
OverviewThe most common types of domain names are hostnames that provide more memorable names to stand in for numeric IP addresses. They allow for any service to move to a different location in the topology of the Internet (or an intranet), which would then have a different IP address.
By allowing the use of unique alphabetical addresses instead of numeric ones, domain names allow Internet users to more easily find and communicate with web sites and other server-based services. The flexibility of the domain name system allows multiple IP addresses to be assigned to a single domain name, or multiple domain names to be assigned to a single IP address. This means that one server may have multiple roles (such as hosting multiple independent Web sites), or that one role can be spread among many servers. One IP address can also be assigned to several servers, as used in anycast and hijacked IP space.
Hostnames are restricted to the ASCII letters "a" through "z" (case-insensitive), the digits "0" through "9", and the hyphen, with some other restrictions. Registrars restrict the domains to valid hostnames, since, otherwise, they would be useless. The Internationalized domain name (IDN) system has been developed to bypass the restrictions on character allowances in hostnames, making it easier for users of non-English alphabets to use the Internet. The underscore character is frequently used to ensure that a domain name is not recognized as a hostname, for example with the use of SRV records, although some older systems, such as NetBIOS did allow it. Due to confusion and other reasons, domain names with underscores in them are sometimes used where hostnames are required.
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. The product that domain name registrars provide to their customers. These names are often called registered domain names. Names used for other purposes in the Domain Name System (DNS), for example the special name which follows the @ sign in an email address, or the Top-level domain names like .com, or the names used by the Session Initiation Protocol (VoIP), or DomainKeys. They are sometimes colloquially (and incorrectly) referred to by marketers as "web addresses". This article will primarily discuss registered domain names. See the Domain Name System article for technical discussions about general domain names and the hostname article for further information about the most common type of domain name.
OverviewThe most common types of domain names are hostnames that provide more memorable names to stand in for numeric IP addresses. They allow for any service to move to a different location in the topology of the Internet (or an intranet), which would then have a different IP address.
By allowing the use of unique alphabetical addresses instead of numeric ones, domain names allow Internet users to more easily find and communicate with web sites and other server-based services. The flexibility of the domain name system allows multiple IP addresses to be assigned to a single domain name, or multiple domain names to be assigned to a single IP address. This means that one server may have multiple roles (such as hosting multiple independent Web sites), or that one role can be spread among many servers. One IP address can also be assigned to several servers, as used in anycast and hijacked IP space.
Hostnames are restricted to the ASCII letters "a" through "z" (case-insensitive), the digits "0" through "9", and the hyphen, with some other restrictions. Registrars restrict the domains to valid hostnames, since, otherwise, they would be useless. The Internationalized domain name (IDN) system has been developed to bypass the restrictions on character allowances in hostnames, making it easier for users of non-English alphabets to use the Internet. The underscore character is frequently used to ensure that a domain name is not recognized as a hostname, for example with the use of SRV records, although some older systems, such as NetBIOS did allow it. Due to confusion and other reasons, domain names with underscores in them are sometimes used where hostnames are required.
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