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.

13 hosts · 312 ms

HostCertsFirst seenLast seenDNS
gls-rtt.com 3 2025-08-14 2026-07-15 ok
*.gls-rtt.com 3 2025-08-14 2026-07-15 —
api.gls-rtt.com 3 2025-10-23 2026-09-23 ok
tracking-api.gls-rtt.com 1 2025-10-22 2025-10-22 nxdomain
campaign.gls-rtt.com 3 2026-01-08 2026-03-05 ok
admin.ads.gls-rtt.com 3 2026-01-08 2026-03-05 ok
links.gls-rtt.com 1 2026-08-25 2026-08-25 ok
ws.gls-rtt.com 1 2026-01-26 2026-01-26 ok
dev.gls-rtt.com 3 2025-08-13 2026-07-14 ok
*.dev.gls-rtt.com 3 2025-08-13 2026-07-14 —
api.dev.gls-rtt.com 3 2025-10-22 2026-09-22 ok
tracking-api.dev.gls-rtt.com 6 2025-10-21 2025-10-22 nxdomain
ws.dev.gls-rtt.com 1 2026-01-25 2026-01-25 ok

Programmatic access, with DNS A records: API GET /v1/hosts/gls-rtt.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/gls-rtt.com.