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.

35 hosts · 346 ms

HostCertsFirst seenLast seenDNS
prefect.io 3 2026-06-13 2026-08-13 ok
docs-v1.prefect.io 5 2026-05-08 2026-09-05 ok
docs-2.prefect.io 5 2026-06-01 2026-09-29 ok
docs-3.prefect.io 4 2026-05-29 2026-09-13 ok
prefab.prefect.io 4 2026-04-17 2026-08-19 ok
sens-o-matic.prefect.io 3 2026-05-07 2026-08-25 ok
docs-self-managed.prefect.io 5 2026-05-29 2026-09-26 ok
docs-customer-managed.prefect.io 5 2026-05-29 2026-09-26 ok
cloud.prefect.io 4 2026-04-18 2026-08-16 ok
marketplace.prefect.io 5 2026-06-04 2026-10-03 ok
reference.prefect.io 5 2026-06-01 2026-09-29 ok
discourse.prefect.io 4 2026-04-10 2026-08-09 ok
dev-log.prefect.io 3 2026-06-09 2026-08-08 ok
auth.prefect.io 4 2026-04-18 2026-08-16 ok
otel.horizon-internal.prefect.io 1 2026-05-28 2026-05-28 ok
otel.dev.horizon-internal.prefect.io 7 2026-05-06 2026-10-06 ok
universal.prefect.io 4 2026-04-18 2026-08-16 ok
upflow-email.prefect.io 4 2026-06-09 2026-10-06 ok
linen.prefect.io 5 2026-04-22 2026-08-27 ok
colin.prefect.io 2 2026-05-25 2026-05-25 nxdomain
horizon.prefect.io 5 2026-05-10 2026-09-11 ok
auth.horizon.prefect.io 10 2026-05-19 2026-09-14 ok
docs.horizon.prefect.io 8 2026-06-22 2026-08-20 ok
status.horizon.prefect.io 3 2026-07-13 2026-09-13 ok
dev.horizon.prefect.io 5 2026-05-10 2026-09-10 ok
www.dev.horizon.prefect.io 4 2026-06-03 2026-10-05 ok
www.horizon.prefect.io 4 2026-06-02 2026-10-06 ok
app.prefect.io 4 2026-04-18 2026-08-16 ok
docs.prefect.io 5 2026-05-25 2026-09-28 ok
orion-docs.prefect.io 5 2026-06-01 2026-09-29 ok
fastmcp-ts.docs.prefect.io 8 2026-06-12 2026-08-10 ok
gtm-automations.prefect.io 1 2026-08-24 2026-08-24 ok
status.prefect.io 5 2026-05-06 2026-09-16 ok
trust.prefect.io 3 2026-05-25 2026-08-16 ok
www.prefect.io 3 2026-06-13 2026-08-14 ok

Programmatic access, with DNS A records: API GET /v1/hosts/prefect.io (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/prefect.io.