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.

10 hosts · 306 ms

HostCertsFirst seenLast seenDNS
isec7.com 12 2026-01-23 2026-09-25 ok
*.isec7.com 9 2026-01-23 2026-09-19 —
blog.isec7.com 12 2026-05-21 2026-09-17 ok
push.isec7.com 1 2026-06-11 2026-06-11 ok
dataroom.isec7.com 5 2026-05-31 2026-09-28 ok
tom.isec7.com 2 2025-11-11 2025-11-11 ok
de-test-tom.isec7.com 1 2025-11-11 2025-11-11 nxdomain
mta-sts.isec7.com 5 2026-05-16 2026-09-13 ok
pushtest.isec7.com 3 2026-06-11 2026-10-03 ok
www.isec7.com 11 2026-05-30 2026-09-25 ok

Programmatic access, with DNS A records: API GET /v1/hosts/isec7.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/isec7.com.