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.

13 hosts · 228 ms

HostCertsFirst seenLast seenDNS
rri.co.jp 1 2025-11-13 2025-11-13 nodata
rrihppre2.rri.co.jp 1 2025-12-24 2025-12-24 ok
wwwpre2.rri.co.jp 2 2025-09-18 2026-09-16 ok
rrihp2.rri.co.jp 1 2025-12-24 2025-12-24 ok
wwwpre3.rri.co.jp 1 2025-10-21 2025-10-21 ok
www3.rri.co.jp 1 2025-11-13 2025-11-13 ok
wwwpre4.rri.co.jp 1 2026-08-05 2026-08-05 ok
wwwpre5.rri.co.jp 8 2026-07-02 2026-09-04 ok
www.wwwpre5.rri.co.jp 2 2026-09-03 2026-09-04 nxdomain
billmgrpre.rri.co.jp 1 2025-11-13 2025-11-13 ok
cryptobin.rri.co.jp 1 2025-11-04 2025-11-04 ok
billmgr.rri.co.jp 1 2025-11-13 2025-11-13 ok
www.rri.co.jp 1 2025-11-13 2025-11-13 ok

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