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 · 228 ms

HostCertsFirst seenLast seenDNS
netanswerplus-t2.resonacard.co.jp 1 2025-11-05 2025-11-05 ok
www4.resonacard.co.jp 2 2026-03-18 2026-08-18 ok
www5.resonacard.co.jp 2 2026-03-18 2026-08-18 ok
search.resonacard.co.jp 2 2025-06-16 2026-06-22 ok
www.saiyo.resonacard.co.jp 2 2025-09-16 2026-09-29 ok
netanswerplus.resonacard.co.jp 2 2025-06-12 2026-06-18 ok
netanswerplus-t.resonacard.co.jp 3 2025-08-21 2026-09-02 ok
websupport.resonacard.co.jp 1 2026-04-17 2026-04-17 ok
xwww.test.resonacard.co.jp 3 2026-06-17 2026-10-05 ok
www.resonacard.co.jp 14 2025-09-02 2026-08-20 ok

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