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

Results forkube.hackerman.ch

Logged At	Not Before	Not After	Common Name	Matching Identities	Issuer Name
2022-01-23T21:05:58.812	2022-01-23T20:05:58	2022-04-23T20:05:57	rancher.kube.hackerman.ch	rancher.kube.hackerman.ch	C=US, O=Let's Encrypt, CN=R3
2022-01-23T21:05:58.526	2022-01-23T20:05:58	2022-04-23T20:05:57	rancher.kube.hackerman.ch	rancher.kube.hackerman.ch	C=US, O=Let's Encrypt, CN=R3
2022-01-23T19:36:04.693	2022-01-23T18:36:03	2022-04-23T18:36:02	rancher.kube.hackerman.ch	rancher.kube.hackerman.ch	C=US, O=Let's Encrypt, CN=R3
2022-01-23T19:36:04.003	2022-01-23T18:36:03	2022-04-23T18:36:02	rancher.kube.hackerman.ch	rancher.kube.hackerman.ch	C=US, O=Let's Encrypt, CN=R3