Monday, February 4, 2008


The 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.


The following example illustrates the difference between a URL (Uniform Resource Locator) and a domain name:

Domain name:
Registered domain name:
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, as referenced in RFC 2606 (Reserved Top Level DNS Names), the server at IP address handles all of the following sites:
When a request is made, the data corresponding to the hostname requested is served to the user.

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.

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, "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 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 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. The third level was commonly used to designate a particular host server. Therefore, might be an FTP server, would be a World Wide Web Server, and 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.

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 could provide domains that are subdomains, such as and

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., instead of A Web site found at will often be advertised without the "http://", and in most cases can be reached by just entering "" 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.

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, resulting in Harris's lament, all the good ones are taken. 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 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.

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 and, 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 and, which use the domain names (of Spain's .es) and, respectively.

Premium domain names

Premium domain names are often valuable, and have particular characterizations: The names are short and memorable, may contain words that are regularly searched on search engines or keywords that help the name gain a higher ranking on search engines. They may contain generic words, so the word has more than one meaning, and they may contain common typos.

Commercial resale of domain names

An economic effect of the widespread usage of domain names has been the resale market (after-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 importance in attracting clients.

The most expensive public sale of an Internet domain name to date, according to DNJournal, is which was sold in 2007 for $9.5 million cash.[citation needed]

There are disputes about the high values of domain names claimed and the actual cash prices of many sales such Another high-priced domain name,, 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. The sale may have never been final as the domain is still with the previous owner. Also, that sale was not just a domain but an income stream, a web site, a domain name with customers and advertisers, etc. Two long-running U.S. lawsuits resulted, one against the thief and one against the domain registrar VeriSign [1]. 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 name with internet entrepreneur Bob Kerstein for the name which was the name of their new operating system. [2]

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. This is known as Direct Navigation or Type-in Traffic. Furthermore, generic domain names such as (now owned by Disney) or (now owned by Barnes & Noble) are extremely easy for potential customers to remember, increasing the probability that they become repeat customers or regular clients. In the case of, Disney has built a stand-alone portal featuring branded content. More and more large brands are beginning to employ a more comprehensive domain strategy featuring a portfolio of thousands of domains, rather than just one or two.

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. [3] 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.

It is very important to remember that a domain (name, address) must be valued separately from the website (content, revenue) that it is used for. The high prices have usually been paid for the revenue that was generated from the website at the domain's address (url.). The intrinsic value of a domain is the registration fee. There is no such a thing as a current market value for a domain, it just takes what somebody pays. The Fair Market Value of a domain can be anything from the registration fee, the lowest known past selling price, the highest known past selling, price, the most recent selling price, or just any past selling price. These (or any sum resp. division etc.) are usually added to the current or expected revenue from the web content (advertising, sales, etc.). The price of a domain (name + ext.) should not be confused with that of a website (content + revenue). An estimate by an appraiser is always the addition of what they would like a domain to be worth together with the effective/expected/desired revenue from the web content. Some people put value on the length of the SLD (name) and other people prefer description capability, but the shorter a SLD is, the less descriptive it can be. Also, if short is crucial, then the TLD (extension) should be short too. It is less realistic to get a domain like or than a domain travel.LL or mobi.LL. This illustrates the relativity of domain value estimation. It can be safely put that the revenue of web (content) can be easily stated, but that the value of a domain (SLD.TLD aka name.ext) is a matter of opinion and preference. In the end, however, any sale depends on the expectations of the domain seller and the domain buyer.

People who buy and sell domain names are known as domainers. People who sell value estimation services are known as appraisers.

According to Guinness World Records and MSNBC, the most expensive domain name sales on record as of 2004 were: for $7.5 million in December 1999, for $5.1 million in January 2000, for $3.3 million in August 1998, for $2.9 million in September 1999, for $2.75 million in July 2004, and for $2.2 million in December 1999.

Domain name confusion

Intercapping is often used to clarify a domain name. However, DNS is case-insensitive, and some names may be misinterpreted when converted to lowercase. For example: Who Represents, a database of artists and agents, chose; a therapists' network thought looked good; and another website operating as of August 2007, is a website for Pen Island, a site that claims to be an online pen vendor, but exists primarily as a joke, as it has no products for sale. Other examples include, website of the Cumming First United Church in Cumming, GA and, a website for an Italian Power Generator company. In such situations, the proper wording can be clarified by use of hyphens. For instance, Experts Exchange, the programmers' site, for a long time used, but ultimately changed the name to

Leo Stoller threatened to sue the owners of on the basis that, when read as, it infringed on claimed trademark rights to the word "stealth". [5]. It's interesting to know that there's no word mark for "stealth" in the USPTO trademark database and Leo Stoller's trademarks on this term are now canceled.