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.

17 hosts · 408 ms

HostCertsFirst seenLast seenDNS
rd.com 12 2026-05-26 2026-09-21 ok
*.rd.com 11 2026-05-26 2026-09-21 —
rs-stripe.rd.com 5 2026-05-18 2026-09-15 ok
sli.rd.com 1 2025-12-14 2025-12-14 ok
ca.mail.rd.com 4 2026-04-12 2026-08-10 ok
e.mail.rd.com 4 2026-04-12 2026-08-10 ok
preferences.mail.rd.com 8 2026-05-12 2026-09-07 ok
images.mail.rd.com 2 2025-08-01 2026-07-02 ok
view.mail.rd.com 2 2025-08-01 2026-07-02 ok
image.email.rd.com 4 2025-06-26 2026-06-01 nxdomain
click.email.rd.com 1 2025-11-06 2025-11-06 nxdomain
pages.email.rd.com 1 2025-11-06 2025-11-06 nxdomain
view.email.rd.com 1 2025-11-06 2025-11-06 nxdomain
digital-database-services.rd.com 4 2026-02-18 2026-10-03 ok
games.rd.com 5 2026-05-22 2026-09-19 ok
bytes.rd.com 3 2026-05-26 2026-08-04 ok
tollbit.rd.com 27 2026-04-07 2026-09-18 ok

Programmatic access, with DNS A records: API GET /v1/hosts/rd.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/rd.com.