The Internet’s Domain Name System (DNS) evolved in the early 1980s as the network expanded from a small directory of hosts to a global decentralized network. DNS makes it possible to locate servers using structured, human-readable names rather than numerical IP addresses.
The Structure of a Web Address
A standard Uniform Resource Locator (URL) represents a specific path to a resource on the web. It consists of three primary components:
$$\text{URL} = \underbrace{\text{https://}}{\text{Protocol}} \ + \ \underbrace{\text{www.}}{\text{Hostname}} \ + \ \underbrace{\text{enterthegroup.com/}}_{\text{Domain Name}}$$
- Protocol: Establishes how data is transmitted. For secure web pages, this is
https(Hypertext Transfer Protocol Secure). - Host Name: Specifies the specific server handling the request, historically
www. - Domain Name: The unique identifier for the site, which always consists of at least two parts: a subdomain or second-level domain (like
enterthegroup) and a Top-Level Domain or TLD (like.com).
When a domain name and host name are combined, the result is a Fully Qualified Domain Name (FQDN). For example, www.enterthegroup.com is an FQDN because it specifies the exact location of the host within the DNS hierarchy.
The Evolution of Top-Level Domains
Historically, the DNS system was divided into a small set of generic Top-Level Domains (gTLDs). Originally, there were seven primary TLDs established in the United States to categorize different types of network entities:
| TLD | Original Purpose | Modern Status |
|---|---|---|
| .com | Commercial entities | Globally open |
| .net | Network infrastructure / providers | Globally open |
| .org | Non-profit organizations | Globally open |
| .edu | Educational institutions | Restricted to accredited entities |
| .gov | U.S. government agencies | Restricted to official entities |
| .mil | U.S. military | Restricted to military branches |
| .int | International treaty organizations | Restricted to treaty-based entities |
Because the United States played a central role in the early development of the internet (funded by DARPA and the NSF), the global DNS root system was configured so that the absence of a country code defaults to these generic zones.
Every other nation uses a designated two-letter country-code Top-Level Domain (ccTLD), such as .uk for the United Kingdom or .hu for Hungary. In the United States, .us serves as the official ccTLD and is often structured with regional geographic subdomains (e.g., ci.boston.ma.us for Boston’s city government).
Historical Registration Restrictions
In the early days of InterNIC, registration policies were strictly managed. Registrants could only easily acquire .com or .us domains. Applying for a .net or .org required providing proof of your status as a network provider or a non-profit organization. Registering a domain like projectname.com, finding it taken, and immediately applying for projectname.net was heavily flagged and scrutinized.
Over the years, ICANN decentralized these rules, turning .com, .net, and .org into open namespaces, followed by the introduction of hundreds of new generic TLDs (like .io, .app, and .dev) to accommodate the modern web.