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 · 240 ms

HostCertsFirst seenLast seenDNS
cybernet.co.jp 2 2025-09-24 2026-09-29 ok
*.cybernet.co.jp 2 2025-09-24 2026-09-29 —
download.cybernet.co.jp 2 2025-12-03 2025-12-15 ok
www.download.cybernet.co.jp 2 2025-12-03 2025-12-15 nxdomain
dl.cybernet.co.jp 4 2025-06-19 2026-07-21 ok
www.dl.cybernet.co.jp 4 2025-06-19 2026-07-21 nxdomain
spdm.cybernet.co.jp 1 2026-05-11 2026-05-11 nxdomain
www.spdm.cybernet.co.jp 1 2026-05-11 2026-05-11 nxdomain
form.cybernet.co.jp 4 2025-06-19 2026-07-17 ok
www.form.cybernet.co.jp 4 2025-06-19 2026-07-17 nxdomain
ansys.cybernet.co.jp 2 2025-12-03 2025-12-15 ok
www.ansys.cybernet.co.jp 2 2025-12-03 2025-12-15 nxdomain
mlit.cybernet.co.jp 9 2026-04-19 2026-09-15 ok
dx-support.cybernet.co.jp 4 2026-04-19 2026-08-17 ok
download-test.cybernet.co.jp 1 2025-12-15 2025-12-15 ok
dl-test.cybernet.co.jp 2 2025-07-08 2026-07-07 ok
www.dl-test.cybernet.co.jp 1 2026-07-07 2026-07-07 nxdomain
form-test.cybernet.co.jp 2 2025-07-08 2026-07-07 ok
www.form-test.cybernet.co.jp 1 2026-07-07 2026-07-07 nxdomain
ansys-test.cybernet.co.jp 1 2025-12-15 2025-12-15 ok
synergy.cybernet.co.jp 1 2025-10-28 2025-10-28 ok

Programmatic access, with DNS A records: API GET /v1/hosts/cybernet.co.jp (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/cybernet.co.jp.