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.

12 hosts · 287 ms

HostCertsFirst seenLast seenDNS
roberthalf.net 2 2025-11-08 2026-01-28 ok
*.roberthalf.net 2 2025-11-08 2026-01-28 —
c3e.roberthalf.net 1 2026-06-30 2026-06-30 nxdomain
www.c3e.roberthalf.net 1 2026-06-30 2026-06-30 nxdomain
premise.roberthalf.net 3 2025-11-07 2026-07-17 ok
www.premise.roberthalf.net 1 2025-11-07 2025-11-07 nxdomain
rhmail.roberthalf.net 2 2025-11-12 2026-07-17 nxdomain
premise-smtp.roberthalf.net 2 2025-11-12 2026-07-17 nxdomain
autodiscover.roberthalf.net 2 2025-11-12 2026-07-17 ok
www.roberthalf.net 1 2025-11-08 2025-11-08 ok
gateway.roberthalf.net 2 2025-07-21 2026-07-14 ok
www.gateway.roberthalf.net 2 2025-07-21 2026-07-14 nxdomain

Programmatic access, with DNS A records: API GET /v1/hosts/roberthalf.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/roberthalf.net.