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.

25 hosts · 270 ms

HostCertsFirst seenLast seenDNS
sermo.com 38 2025-11-11 2026-09-25 ok
*.sermo.com 38 2025-11-11 2026-09-25 —
mktpublic.sermo.com 2 2025-09-27 2026-08-28 ok
e.sermo.com 10 2026-05-07 2026-09-03 ok
share.sermo.com 1 2025-11-13 2025-11-13 ok
wiki.sermo.com 5 2026-05-18 2026-09-16 ok
cloud.email.sermo.com 3 2026-03-16 2026-08-17 ok
image.email.sermo.com 8 2026-03-16 2026-09-08 ok
click.email.sermo.com 3 2026-03-16 2026-08-18 ok
view.email.sermo.com 5 2026-03-16 2026-08-17 ok
design.sermo.com 11 2026-05-18 2026-09-13 ok
lp.sermo.com 8 2026-05-11 2026-09-06 ok
help.sermo.com 1 2026-03-26 2026-03-26 ok
s.sermo.com 6 2026-05-06 2026-09-01 ok
rtanalytics.sermo.com 5 2026-05-05 2026-09-03 ok
signatures.sermo.com 4 2026-06-08 2026-10-06 ok
cloud.campaigns.sermo.com 2 2026-03-31 2026-09-01 ok
image.campaigns.sermo.com 15 2026-03-31 2026-09-18 ok
click.campaigns.sermo.com 2 2026-03-31 2026-09-02 ok
view.campaigns.sermo.com 2 2026-03-31 2026-09-02 ok
share-us.sermo.com 1 2025-11-13 2025-11-13 ok
connect.sermo.com 10 2026-05-11 2026-09-13 ok
salesloft.sermo.com 5 2026-05-27 2026-09-24 ok
support.sermo.com 5 2026-05-08 2026-09-05 ok
share-eu.sermo.com 1 2025-11-13 2025-11-13 ok

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