.arpa domains list

What is .arpa TLD

The .arpa top-level domain is an infrastructure-only namespace used for core Internet functions, not for general registration or branding. It underpins reverse DNS for IPv4 (in-addr.arpa) and IPv6 (ip6.arpa), along with other protocol mappings. In our global index of .arpa domains, we currently observe 32 active delegations. Among them, we detect 1 live .arpa websites in the wild, and just 1 with resolvable DNS records, reflecting its operational rather than content-focused role. These measurements are consistent with a centrally managed zone with limited surface for web crawling. For analysts evaluating infrastructure namespaces, we provide neutral coverage, change tracking, and exportable inventories to support due diligence and research. Download the .arpa dataset from webatla.

History and key features of .arpa TLD

Historically, .arpa originated in the early Internet as a transitional label and was retained as the Address and Routing Parameter Area for permanent technical use. Governance is tightly controlled, and subdomains are created to support standards like ENUM (e164.arpa) and URI resolution scopes. Characteristic features include restricted eligibility, stability of delegations, and a design optimized for protocol signaling rather than content. Reflecting this, our telemetry shows no organic growth pressure: 0 new .arpa domains last week and 0 in November 2025 overall in our latest monthly window. Correspondingly, .arpa websites are exceptionally scarce across our web sensors. For concise, longitudinal evidence on this infrastructure TLD, we maintain reproducible time series and zone snapshots. Get historical .arpa domain datasets from webatla.

Why and who choose the .arpa domain

Use of the .arpa domain is driven by protocol needs and stewardship by technical authorities, not by market demand. Typically, allocations support reverse lookups, address mapping, and standardized discovery operated by IANA, regional Internet registries, and similar entities. This explains why .arpa domains are few compared with general-purpose namespaces and why .arpa websites rarely host conventional content. Our measurements align with this specialization: 0 countries show adoption signals in our geolocation model, 1 domains resolve, and total active objects stand at 32. For security teams and researchers, these constraints simplify monitoring while emphasizing the importance of completeness and provenance in datasets. Download operational .arpa domain intelligence from webatla.