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.

12 hosts · 358 ms

HostCertsFirst seenLast seenDNS
asc.cat 2 2026-02-06 2026-02-06 ok
sud.asc.cat 1 2026-05-18 2026-05-18 ok
www.sud.asc.cat 1 2026-05-18 2026-05-18 nxdomain
pre.asc.cat 9 2026-04-18 2026-09-14 ok
www.pre.asc.cat 9 2026-04-18 2026-09-09 ok
comunicacions.asc.cat 3 2026-06-02 2026-08-10 ok
multimedia.comunicacions.asc.cat 3 2026-06-02 2026-08-10 ok
www.comunicacions.asc.cat 3 2026-06-02 2026-08-10 ok
mta-sts.asc.cat 3 2026-06-06 2026-08-06 ok
dev.asc.cat 3 2026-05-29 2026-08-11 ok
www.dev.asc.cat 3 2026-05-29 2026-08-11 ok
www.asc.cat 2 2026-02-06 2026-02-06 ok

Programmatic access, with DNS A records: API GET /v1/hosts/asc.cat (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/asc.cat.