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.

4 hosts · 324 ms

HostCertsFirst seenLast seenDNS
ca.mail.comms.yahoo.net 2 2026-03-13 2026-08-06 ok
e.mail.comms.yahoo.net 2 2026-03-13 2026-08-06 ok
images.mail.comms.yahoo.net 2 2026-03-13 2026-08-06 ok
view.mail.comms.yahoo.net 2 2026-03-13 2026-08-06 ok

Programmatic access, with DNS A records: API GET /v1/hosts/mail.comms.yahoo.net (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/mail.comms.yahoo.net.