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.

11 hosts · 174 ms

HostCertsFirst seenLast seen
dfns.co 6 2026-05-19 2026-06-04
helpdesk.dfns.co 3 2026-04-17 2026-09-17
portal.helpdesk.dfns.co 3 2026-04-17 2026-09-17
docs.dfns.co 17 2026-04-21 2026-09-01
links.dfns.co 5 2026-05-19 2026-09-18
status.dfns.co 5 2026-05-25 2026-09-21
support.dfns.co 5 2026-02-24 2026-10-05
portal.support.dfns.co 3 2026-02-24 2026-09-29
preview.dfns.co 3 2026-06-02 2026-06-02
www.dfns.co 7 2026-05-06 2026-06-04
docs-legacy.dfns.co 4 2026-05-16 2026-05-17

Programmatic access: API GET /v1/hosts/dfns.co (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/dfns.co.