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.

20 hosts · 317 ms

HostCertsFirst seenLast seenDNS
arstechnica.com 3 2025-07-27 2026-06-25 ok
*.arstechnica.com 3 2025-07-27 2026-06-25 —
c2.arstechnica.com 6 2025-12-29 2026-05-06 ok
c.arstechnica.com 6 2025-12-29 2026-05-06 ok
qc.arstechnica.com 10 2025-09-23 2026-08-24 ok
irc.arstechnica.com 5 2026-05-19 2026-09-16 ok
irc-nyc.arstechnica.com 5 2026-05-19 2026-09-16 ok
archive.arstechnica.com 4 2026-04-21 2026-08-20 ok
permutive.arstechnica.com 4 2026-04-16 2026-09-07 ok
staging.arstechnica.com 5 2025-07-28 2026-09-15 ok
*.staging.arstechnica.com 5 2025-07-28 2026-09-15 —
fpa-api.arstechnica.com 1 2025-12-25 2025-12-25 ok
link.arstechnica.com 5 2026-04-23 2026-08-21 ok
fpa-cdn.arstechnica.com 1 2025-12-25 2025-12-25 ok
video.arstechnica.com 1 2025-12-09 2025-12-09 ok
irc-sfo.arstechnica.com 5 2026-05-19 2026-09-16 ok
links.arstechnica.com 2 2026-06-02 2026-06-02 ok
frontiers.arstechnica.com 13 2026-06-06 2026-10-02 ok
events.arstechnica.com 5 2026-05-06 2026-09-03 ok
fpa-events.arstechnica.com 1 2025-12-25 2025-12-25 ok

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