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.

9 hosts · 271 ms

HostCertsFirst seenLast seenDNS
res8.email.adopt.com 1 2026-02-18 2026-02-18 ok
t8.email.adopt.com 2 2026-02-18 2026-02-18 ok
m9.email.adopt.com 2 2026-02-18 2026-02-18 ok
res9.email.adopt.com 1 2026-02-18 2026-02-18 ok
t9.email.adopt.com 2 2026-02-18 2026-02-18 ok
web.email.adopt.com 2 2026-02-18 2026-02-18 ok
m.email.adopt.com 7 2026-02-18 2026-09-29 ok
res.email.adopt.com 7 2026-02-18 2026-09-29 ok
t.email.adopt.com 8 2026-02-18 2026-09-29 ok

Programmatic access, with DNS A records: API GET /v1/hosts/email.adopt.com (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/email.adopt.com.