Find every subdomain
of a domain.

Every hostname under a domain that ever appeared in a public TLS certificate — with certificate counts and first/last seen dates.

10 hosts · 252 ms

Download CSV
HostCertsFirst seenLast seen
email.edu.microsoft.com 12 2026-01-07 2026-09-24
m132.email.edu.microsoft.com 4 2026-01-07 2026-09-24
res132.email.edu.microsoft.com 4 2026-01-07 2026-09-24
t132.email.edu.microsoft.com 4 2026-01-07 2026-09-24
m135.email.edu.microsoft.com 5 2026-01-07 2026-09-18
res135.email.edu.microsoft.com 5 2026-01-07 2026-09-18
t135.email.edu.microsoft.com 5 2026-01-07 2026-09-18
m.email.edu.microsoft.com 3 2026-01-07 2026-09-15
res.email.edu.microsoft.com 3 2026-01-07 2026-09-15
t.email.edu.microsoft.com 3 2026-01-07 2026-09-15

Programmatic access: API GET /v1/hosts/edu.microsoft.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/edu.microsoft.com.