defaults.exposed Domain Security Census: Aggregate Dataset

defaults.exposed runs a monthly census of domain security posture across the global registered domain population, measuring DNS security, email authentication (SPF, DKIM, DMARC), TLS and certificate configuration, and web security headers. The census scores each domain against a public methodology and assigns a letter grade from A+ to F.

This record contains the aggregate outputs of one census edition: per-TLD grade distributions, per-check pass rates across the full 34-check methodology, certificate authority market share, DMARC policy adoption and enforcement, mail and nameserver provider concentration, TLS protocol version adoption, and overall population counts (graded, unreachable, indeterminate, dead).

This dataset excludes per-domain records and publishes only population-level aggregates, in line with the terms of the underlying zone-file data sources.

See the included README.md for the full file list and schema notes.

Full methodology: https://defaults.exposed/methodology

Live data explorer: https://defaults.exposed/data

Census overview: https://defaults.exposed/census

New editions are added to this record as new versions on a monthly cadence.

This version: September 2026 edition, snapshot 2026-09-05. Domains carrying a grade: 316,600,902. Domains scanned: 347,691,016, across 1,285 top-level domains. This record holds the 12 raw JSON exports plus README; two site-only summary files (census.json and tld-grades.csv) are published at https://defaults.exposed/data.