Live lookups
- DNS: queried live through public resolvers (Cloudflare 1.1.1.1, Google 8.8.8.8, Quad9) or directly against a domain's authoritative name servers.
- TLS certificates: read from a live TLS handshake with the host.
- HTTP: real requests from our servers; only public addresses are contacted.
- Domain WHOIS / RDAP: queried live from the registry; personal data redacted by registries stays redacted, and we do not store WHOIS contact data.
- Certificate Transparency: certificates logged for a domain, read from crt.sh (one request per lookup, cached 6 hours).
- IP geolocation (IP information tool): ipinfo.io API.
Registries and datasets
- Ports and HTTP status codes: IANA Service Name and Transport Protocol Port Number Registry and the HTTP Status Code Registry (IANA licensing terms, CC0).
- MAC address vendors: the public IEEE Registration Authority assignment listings (MA-L, MA-M, MA-S). © IEEE.
- IP-to-ASN and country: iptoasn.com, public domain (PDDL v1.0), refreshed daily.
- Top-level domains: the IANA root zone database and the Public Suffix List (MPL 2.0).
- Domain sample for studies: the Tranco research list; each study cites the list ID it used. We publish only our own measurements, not the list itself.
Our own measurements
Provider, TLD and certificate-authority statistics come from our own periodic, rate-limited scans of public DNS and TLS for a sample of popular domains. Each statistic shows the scan date and sample size.
Caching
- Full DNS reports: 1 hour (use “Refresh” for a new check).
- Domain WHOIS: 1 day. IP WHOIS: 7 days. IP information: 1 day.
- Registry datasets: refreshed daily to monthly, as noted on each page.
Automation disclosure
Reference pages are assembled by code from the data above. Explanatory text is drafted with AI assistance and checked against the cited standards before publishing; no page is generated from a prompt at request time. Results that come from a lookup are labelled with the time they were checked.