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.

8 hosts · 353 ms

HostCertsFirst seenLast seenDNS
costcotravel.ca 2 2025-11-17 2026-01-16 ok
ppe1.costcotravel.ca 4 2025-11-20 2026-09-23 ok
ccr1ppe1.costcotravel.ca 1 2025-11-20 2025-11-20 ok
us03p02000002.costcotravel.ca 1 2026-01-16 2026-01-16 ok
beta.costcotravel.ca 1 2025-11-17 2025-11-17 ok
consumer.preview.ppe.costcotravel.ca 1 2026-04-20 2026-04-20 ok
m.costcotravel.ca 1 2025-11-17 2025-11-17 nxdomain
www.costcotravel.ca 2 2025-11-17 2026-01-16 ok

Programmatic access, with DNS A records: API GET /v1/hosts/costcotravel.ca (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/costcotravel.ca.