Domain name
From Wikipedia, the free encyclopedia
The term domain name has multiple related meanings:
- A name that is entered into a computer (e.g. as part of a Web site or other URL, or an e-mail address) then looked up in the global Domain Name System (DNS) which informs the computer of the IP address(es) assigned to that name.
- The product that registrars provide to their customers.
- A name looked up in the DNS for other purposes.
They are sometimes colloquially (and incorrectly) referred to by marketers as "Web addresses".
- The authoritative definition is that given in the RFCs that define the DNS.
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 another internet), which would then have a different IP address.
Each string of letters, digits and hyphens between the dots is called a label in the parlance of the domain name system (DNS). Valid labels are subject to certain rules, which have relaxed over the course of time. The original rules state that labels must start with a letter, and end with a letter or digit; any intervening characters may be letters, digits, or hyphens. Labels must be between 1 and 63 characters long (inclusive). Letters are ASCII A–Z and a–z; domain names are compared case-insensitively. Later it became permissible for labels to commence with a digit (but not for domain names to be entirely numeric), and for labels to contain internal underscores, but support for such domain names is uneven. These are the rules imposed by the way names are looked up ("resolved") by DNS. Some top level domains (see below) impose more rules, such as a longer minimum length, on some labels. Fully qualified domain names (FQDNs) are sometimes written with a final dot.
By making possible the use of unique alphabetical addresses instead of numeric ones, domain names allow Internet users to 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 one role can be spread among many servers. One IP address can even be assigned to several servers, such as with anycast and hijacked IP space.
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[edit] Examples
The following example illustrates the difference between a URL (Uniform Resource Locator) and a domain name:
- URL: http://www.example.com/
- Domain name: example.com
As a general rule, the IP address and the server name are interchangeable. For most Internet services, the server will not have any way to know which was used. However, the explosion of interest in the Web means that there are far more Web sites than servers. To accommodate this, the hypertext transfer protocol (HTTP) specifies that the client tells the server which name is being used. This way, one server with one IP address can provide different sites for different domain names. This feature goes under the name virtual hosting and is commonly used by Web hosts.
For example, the server at 192.0.34.166 handles all of the following sites:
- example1.com
- example2.net
- example3.org
When a request is made, the data corresponding to the hostname requested, is served to the user.
[edit] 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 characters 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:
| Generic top-level domains | ||
|---|---|---|
| Unsponsored | .biz .com .edu .gov .info .int .mil .name .net .org | |
| Sponsored | .aero .cat .coop .jobs .mobi .museum .pro .travel | |
| Infrastructure | .arpa .root | |
| Startup phase | .asia .tel | |
| Proposed | .cym .geo .kid .kids .mail .post .sco .web .xxx | |
| Deleted/retired | .nato | |
| Reserved | .example .invalid .localhost .test | |
| Pseudo-domains | .bitnet .csnet .local .onion .uucp | |
| Unofficial | see Alternative DNS roots | |
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See also: Country code top-level domains |
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The country code top-level domain (ccTLD) extensions are:
[edit] Other-level domains
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.
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).
[edit] Official assignment
ICANN (Internet Corporation for Assigned Names and Numbers) has overall responsibility for managing the DNS. It controls the root domain, delegating control over each top-level domain to a domain name registry. For ccTLDs, the domain registry is typically controlled by the government of that country. ICANN has a consultation role in these domain registries but is in no position to regulate the terms and conditions of how a domain name is allocated or who allocates it in each of these country level domain registries. On the other hand, generic top-level domains (gTLDs) are governed directly under ICANN which means all terms and conditions are defined by ICANN with the cooperation of the gTLD registries.
Domain names which are theoretically leased can be considered in the same way as real estate, due to a significant impact on online brand building, advertising, search engine optimization, etc.
A few companies have offered low-cost, below-cost or even free domain registrations, with a variety of models adopted to recoup the costs to the provider. These usually require that domains are hosted on their site in a framework or portal, with advertising wrapped around the user's content, revenue from which allows the provider to recoup the costs. When the DNS was new, domain registrations were free. A domain owner can generally give away or sell infinite subdomains of their domain, e.g. the owner of example.edu could provide domains that are subdomains, such as foo.example.edu and foo.bar.example.edu.
[edit] 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.
[edit] Generic domain names — problems arising out of unregulated name selection
Within a particular top-level domain, parties are generally free to select an unallocated domain name as their own on a first come, first served basis. For generic or commonly used names, this may sometimes lead to the use of a domain name which is inaccurate or misleading. This problem can be seen with regard to the ownership or control of domain names for a generic product or service.
By way of illustration, there has been tremendous growth in the number and size of literary festivals around the world in recent years. In this context, currently a generic domain name such as literary.org is available to the first literary festival organisation which is able to obtain registration, even if the festival in question is very young or obscure. Some critics would argue that there is greater amenity in reserving such domain names for the use of, for example, a regional or umbrella grouping of festivals. Related issues may also arise in relation to non-commercial domain names.
[edit] Unconventional domain names
Due to the rarity of one-word dot-com domain names, many unconventional domain names, domain hacks, have been gaining popularity. They make use of the top-level domain as an integral part of the Web site's title. Two popular domain hack Web sites are del.icio.us and blo.gs, which spell out "delicious" and "blogs", respectively.
Unconventional domain names are also used to create unconventional email addresses. Non-working examples that spell 'James' are j@m.es and j@mes.com, which use the domain names m.es (of Spain's .es) and mes.com, respectively.
[edit] Commercial resale of domain names
An economic effect of the widespread usage of domain names has been the resale market for generic domain names that has sprung up in the last decade. Certain domains, especially those related to business, gambling, pornography, and other commercially lucrative fields of digital world trade have become very much in demand to corporations and entrepreneurs due to their intrinsic value in attracting clients. The most expensive Internet domain name to date, according to Guinness World Records, is business.com which was resold in 1999 for $7.5 million, but this was $7.5 million in stock options, not in cash. Later the stock was valued at, not sold, for $2 million and may even be worth less today Newsweek [1]. There are disputes about the high values of domain names claimed and the actual prices of many sales.
Another high value domain name, sex.com, was stolen from its rightful owner by means of a forged transfer instruction via fax. During the height of the dot-com era, the domain was earning millions of dollars per month in advertising revenue from the large influx of visitors that arrived daily. Two long-running U.S. lawsuits resulted, one against the thief and one against the domain registrar VeriSign[2]. In one of the cases, Kremen v. Network Solutions, the court found in favor of the plaintiff, leading to an unprecedented ruling that classified domain names as property, granting them the same legal protections. In 1999, Microsoft traded the valuable name Bob.com with internet entrepreneur Bob Kerstein for the name Windows2000.com which was the name of their new operating system.[3]
One of the reasons for the value of domain names is that even without advertising or marketing, they attract clients seeking services and products who simply type in the generic name. Furthermore, generic domain names such as movies.com or Books.com are extremely easy for potential customers to remember, increasing the probability that they become repeat customers or regular clients.
Although the current domain market is nowhere as strong as it was during the dot-com heyday, it remains strong and is currently experiencing solid growth again. Annually tens of millions of dollars change hands due to the resale of domains. Large numbers of registered domain names lapse and are deleted each year. On average 25,000 domain names drop (are deleted) every day.
People who buy and sell domain names are known as domainers.
[edit] Caveat emptor
Care should always be exercised when registering a domain name: DNS is case-insensitive and the modern trend of words run together with intercapping can be misinterpreted when converted to lowercase. Who Represents, a database of artists and agents, chose whorepresents.com; a therapists' network thought therapistfinder.com looked good; Experts Exchange, the programmers' site, for a long time had expertsexchange.com; Another website operating as of October, 2006, is penisland.net, a website for Pen Island, an online pen vendor.
In such situations, the proper wording can be clarified by use of hyphens. For instance, expertsexchange.com changed its name to experts-exchange.com.
DNS is case-insensitive, so such Web sites can also be further clarified by advertising them with proper capitalization. For instance, TherapistFinder.com.
[edit] See also
- Domaining
- Domain hack
- Domain kiting
- Domain name warehousing
- ICANN
- Internationalized domain names
- Uniform Resource Locator
- World Wide Web
- Web page
- Web site
- Geodomain
[edit] External links
- RFC 1034, Domain Names—Concepts and Facilities, an Internet Protocol Standard.
- ICANN - Internet Corporation for Assigned Names and Numbers.
- UDRP, Uniform Domain-Name Dispute-Resolution Policy.
- Internic.net, public information regarding Internet domain name registration services.
