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.

24 hosts · 324 ms

HostCertsFirst seenLast seenDNS
syntrio.net 17 2026-04-14 2026-09-24 ok
*.syntrio.net 15 2026-05-22 2026-09-24 —
beyondtrustapp01.syntrio.net 1 2026-04-20 2026-04-20 nxdomain
smtprelay01.syntrio.net 1 2025-09-30 2025-09-30 ok
oklbomgarpa1.syntrio.net 2 2025-09-29 2026-02-20 nxdomain
vrnbomgarpa1.syntrio.net 2 2025-09-29 2026-02-20 nxdomain
btpasswordsafe1.syntrio.net 1 2026-04-06 2026-04-06 nxdomain
beyondtrustapp02.syntrio.net 1 2026-04-20 2026-04-20 nxdomain
smtprelay02.syntrio.net 1 2025-09-30 2025-09-30 ok
btpasswordsafe2.syntrio.net 1 2026-04-06 2026-04-06 nxdomain
pa.syntrio.net 2 2025-09-29 2026-02-20 ok
hub.syntrio.net 8 2026-05-15 2026-09-11 ok
onehub.syntrio.net 5 2026-05-06 2026-09-04 ok
land.syntrio.net 10 2026-05-17 2026-09-13 ok
businessvoice.syntrio.net 8 2026-05-18 2026-09-13 ok
myvoice.syntrio.net 7 2026-05-18 2026-09-13 ok
passwordsafe.syntrio.net 1 2026-04-06 2026-04-06 nxdomain
blog.syntrio.net 8 2026-04-25 2026-08-21 ok
business.syntrio.net 5 2026-03-06 2026-09-14 ok
it.syntrio.net 1 2026-04-20 2026-04-20 ok
support.syntrio.net 1 2026-04-20 2026-04-20 ok
www.syntrio.net 2 2026-04-14 2026-04-14 ok
smtprelay.syntrio.net 2 2025-09-30 2026-02-23 ok
pay.syntrio.net 1 2026-04-09 2026-04-09 ok

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