Websites are identified by their Internet Protocol (IP) address. An IP address is a series of numbers broken up with periods. Domain names were adopted in part because it’s much easier to remember an alphanumeric title than it is to recall strings of numbers. The Domain Name System (DNS) is a hierarchical, or tree-like, naming system that translates the numerical IP address needed by computers into the easy-to-remember domain name that we use. This naming hierarchy consists of the top-level domain, second level domain, and a sub-domain. Let’s break down each in turn.
The top-level domain name (TLD) is the last part of the website that you enter. It comes in two categories: generic and geographic. Generic top-level domains are those encountered most often on the Internet in the United States and denote different organizational domains. For instance, “.com” represents a commercial organization; “.edu” signifies the website is for an educational institution, and “.gov” will take you to a government webpage. Other common top level domains include “.net” and “.org”, but there are many more.
Geographic domains, on the other hand, are top-level domains used by other countries. To illustrate using Google once more, if you enter www.google.fr in your browser, you’ll be taken to Google’s French webpage.
ICANN (the Internet Corporation for Assigned Names and Numbers) has dramatically expanded the TLD space in recent years. Hundreds of new generic TLDs have been introduced, including “.law”, “.legal”, “.tech”, “.shop”, “.app”, and many others. While “.com” remains dominant for commercial purposes, new TLDs offer branding opportunities and — in some cases — create legal issues when they are used in ways that infringe existing trademarks.
The second level domain (SLD) is the portion of the address located directly to the left of the TLD. It is the most recognizable part of the domain name and typically represents the brand, business, or individual who owns the website. In “revisionlegal.com,” the SLD is “revisionlegal.” In “google.com,” it is “google.”
The SLD is also where most legal disputes involving domain names arise. Cybersquatters register SLDs that incorporate well-known trademarks to profit from consumer confusion, demand payment from the trademark owner, or divert web traffic. The Anti-Cybersquatting Consumer Protection Act (ACPA), 15 U.S.C. § 1125(d), provides a federal cause of action against bad-faith registrations of domain names that are identical or confusingly similar to a distinctive or famous mark. ICANN’s Uniform Domain-Name Dispute-Resolution Policy (UDRP) provides a faster administrative remedy through arbitration.
A subdomain appears to the left of the SLD, separated by a dot. The most familiar subdomain is “www” — which originally stood for “World Wide Web” and directed browsers to the web server for the domain. Today, “www” is largely vestigial; most modern websites respond identically to requests at “www.example.com” and “example.com.”
Subdomains serve important functional purposes beyond the familiar “www.” They are used to organize large websites into distinct sections or to host entirely separate services under the same domain. Common examples include:
Understanding domain name structure is not merely a technical exercise — it has direct legal implications. Courts and arbitration panels regularly analyze TLDs, SLDs, and subdomains in trademark and domain dispute contexts:
Courts have generally held that TLDs (e.g., “.com”, “.net”) are given little to no weight in determining whether a domain name is confusingly similar to a trademark. A cybersquatter who registers “nike.org” cannot avoid liability simply because the infringing domain uses “.org” rather than “.com.” The UDRP panels consistently apply this principle. However, descriptive TLDs like “.law” or “.legal” can affect analysis when combined with generic SLDs.
Subdomains can also become the subject of trademark disputes. A party who does not own a trademark but uses it as a subdomain on their website (e.g., “nike.competitor.com”) may face both trademark infringement and cybersquatting claims depending on how the subdomain is used. Courts have found ACPA liability in subdomain cases, though the analysis is more nuanced than for SLD-based squatting.
WHOIS records — the publicly accessible database of domain registration information — identify who owns the SLD and under which registrar. In litigation and UDRP proceedings, WHOIS records are treated as prima facie evidence of ownership. They are also central to proving bad faith in cybersquatting cases, particularly where the registrant has a pattern of registering marks owned by others or has provided false registration information.
Brand owners should register their trademarks as domain names across the most commercially significant TLDs — at minimum “.com” and “.net” — to prevent third parties from registering confusingly similar domains. Defensive registration of common misspellings and typos (typosquatting variants) is also prudent for high-value brands. The cost of defensive registrations is a fraction of the cost of pursuing a cybersquatter through UDRP or federal litigation after the fact.
If you are dealing with a domain name dispute, a cybersquatting issue, or simply want to understand how to build and protect your online brand, contact Revision Legal. Our internet lawyers handle domain name disputes, UDRP proceedings, ACPA claims, and trademark registrations for clients across the country. Call 855-473-8474 or complete the contact form on this page to speak with an attorney.
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