Find every subdomain
of a domain.

Every hostname under a domain that ever appeared in a public TLS certificate — with certificate counts, first/last seen and live DNS status.

21 hosts · 400 ms

HostCertsFirst seenLast seenDNS
testsift.com 120 2026-04-24 2026-09-25 ok
*.testsift.com 9 2026-04-24 2026-09-25 —
mta-sts.testsift.com 1 2025-11-18 2025-11-18 ok
mtasts.testsift.com 16 2026-05-06 2026-09-01 nodata
mta-sts.no-id.mtasts.testsift.com 8 2026-05-12 2026-09-07 ok
mta-sts.policy-not-found.mtasts.testsift.com 6 2026-05-18 2026-09-13 ok
mta-sts.enforce.mtasts.testsift.com 6 2026-05-06 2026-09-01 ok
mta-sts.mode.mtasts.testsift.com 6 2026-05-06 2026-09-01 ok
mta-sts.large-max-age.mtasts.testsift.com 6 2026-05-06 2026-09-01 ok
mta-sts.negative-max-age.mtasts.testsift.com 10 2026-05-15 2026-09-10 ok
mta-sts.short-max-age.mtasts.testsift.com 8 2026-05-07 2026-09-02 ok
mta-sts.none.mtasts.testsift.com 6 2026-05-06 2026-09-01 ok
mta-sts.testing.mtasts.testsift.com 6 2026-05-06 2026-09-01 ok
mta-sts.mx-mismatch.mtasts.testsift.com 2 2026-09-04 2026-09-04 ok
*.mta-sts.mx-mismatch.mtasts.testsift.com 2 2026-09-04 2026-09-04 —
mta-sts.no-version.mtasts.testsift.com 6 2026-05-06 2026-09-01 ok
mta-sts.version.mtasts.testsift.com 6 2026-05-06 2026-09-01 ok
mta-sts.full-declination.mtasts.testsift.com 2 2026-08-21 2026-08-21 ok
*.mta-sts.full-declination.mtasts.testsift.com 2 2026-08-21 2026-08-21 —
mta-sts.no-mx.mtasts.testsift.com 6 2026-05-06 2026-09-01 ok
mta-sts.invalid-policy.mtasts.testsift.com 11 2026-05-20 2026-09-15 ok

Programmatic access, with DNS A records: API GET /v1/hosts/testsift.com (API key for paging).

Shown here: hostnames with a certificate that is valid now or expired within the last 90 days. The full history since 2013 — hostnames whose last certificate expired earlier — is a Pro plan method: GET /v1/hosts-history/testsift.com.