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.

7 hosts · 300 ms

HostCertsFirst seenLast seenDNS
nnn.or.jp 5 2026-05-24 2026-09-20 ok
b.nnn.or.jp 5 2026-04-29 2026-08-26 ok
d.nnn.or.jp 5 2026-05-06 2026-09-04 ok
m.nnn.or.jp 5 2026-05-23 2026-09-20 ok
s.nnn.or.jp 10 2026-05-18 2026-10-03 ok
mta-sts.nnn.or.jp 5 2026-05-19 2026-09-16 ok
www.nnn.or.jp 5 2026-05-24 2026-09-20 ok

Programmatic access, with DNS A records: API GET /v1/hosts/nnn.or.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/nnn.or.jp.