It can be anything! An apex, subdomain, or even a URL.

Results formembership.thestacksystem.com

Logged At	Not Before	Not After	Common Name	Matching Identities	Issuer Name
2025-12-18T16:32:50.167	2025-12-18T15:31:28	2026-03-18T16:31:21	membership.thestacksystem.com	membership.thestacksystem.com	C=US, O=Google Trust Services, CN=WE1
2025-12-18T16:31:29.414	2025-12-18T15:31:28	2026-03-18T16:31:21	membership.thestacksystem.com	membership.thestacksystem.com	C=US, O=Google Trust Services, CN=WE1
2025-12-18T16:31:15.843	2025-12-18T15:31:15	2026-03-18T16:29:52	membership.thestacksystem.com	membership.thestacksystem.com	C=US, O=Google Trust Services, CN=WR1
2025-10-20T15:00:58.898	2025-10-20T12:02:02	2026-01-18T13:01:52	membership.thestacksystem.com	membership.thestacksystem.com	C=US, O=Google Trust Services, CN=WE1
2025-10-20T13:02:02.949	2025-10-20T12:02:02	2026-01-18T13:01:52	membership.thestacksystem.com	membership.thestacksystem.com	C=US, O=Google Trust Services, CN=WE1
2025-10-20T13:01:47.262	2025-10-20T12:01:46	2026-01-18T12:55:20	membership.thestacksystem.com	membership.thestacksystem.com	C=US, O=Google Trust Services, CN=WR1