DNS authoritative-NS providers observed across the Tranco top-1M. Each apex domain is classified by the suffix of its NS hostnames; we then cross-tab against TLDs, regions and mailbox-provider choice.
For each top NS provider: among their domains that publish identifiable mail records, what mailbox provider do they pick?
Source: OpenINTEL forward-DNS Tranco snapshot (2026-07-13).
NS suffix patterns: dictionaries/ns_providers.py.
An apex is called "Self-hosted" only when ALL its NS live under the apex AND no
registered pattern matches; everything else uncatalogued falls into "Self-hosted / Other".