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 · 265 ms

HostCertsFirst seenLast seenDNS
m10.contact.adopt.com 2 2026-02-18 2026-04-29 ok
res10.contact.adopt.com 2 2026-02-18 2026-04-29 ok
t10.contact.adopt.com 2 2026-02-18 2026-04-29 ok
res8.contact.adopt.com 3 2026-02-18 2026-09-29 ok
t8.contact.adopt.com 3 2026-02-18 2026-09-29 ok
web.contact.adopt.com 1 2026-02-18 2026-02-18 nxdomain
m.contact.adopt.com 4 2026-02-18 2026-09-29 ok
res.contact.adopt.com 2 2026-02-18 2026-04-29 ok
t.contact.adopt.com 3 2026-02-18 2026-09-29 ok

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