TLDn

TLDn, short for Top-Level Domain n, is a hypothetical extension to the Domain Name System (DNS) used in discussions about scalable namespace expansion. In the TLDn concept, the set of top-level domains would be organized into families by attaching a numeric index to the base TLD, creating separate, independently manageable top-level namespaces. TLDn is not an established standard and has not been adopted by ICANN or major registries.

Structure and operation: A TLDn label designates a distinct top-level namespace. For example, a base TLD such as example could be extended with suffixes to yield identifiers like example1, example2, and so on. Each TLDn operates as its own zone with separate registries, policy rules, and DNSSEC coverage, while still integrating with the broader DNS hierarchy. Adoption would require root-zone changes, registry coordination, and resolver support to avoid cross-namespace confusion.

Status and reception: The concept has appeared mainly in theoretical discussions and academic papers about DNS scalability and namespace management. It has no official specification or practical deployment, and it remains a topic for speculative analysis rather than a concrete proposal at present.

Potential implications: Proponents argue that TLDn could enable safer testing of new policies, reduce collision risk among rapidly issued new gTLDs, and provide clearer categorization of namespaces. Critics warn that it would complicate the DNS ecosystem, confuse users, increase management overhead, and raise security and interoperability concerns if not globally standardized.

See also: Domain name system, top-level domain, ICANN, DNSSEC, IDN.