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

Results for*.pbntesting.com

Logged At	Not Before	Not After	Common Name	Matching Identities	Issuer Name
2020-03-13T19:25:18.925	2020-03-11T00:00:00	2020-10-09T12:00:00	sni.cloudflaressl.com	*.pbntesting.com	C=US, ST=CA, L=San Francisco, O="CloudFlare, Inc.", CN=CloudFlare Inc ECC CA-2
2020-03-13T19:25:18.925	2020-03-11T00:00:00	2020-10-09T12:00:00	sni.cloudflaressl.com	*.pbntesting.com	C=US, ST=CA, L=San Francisco, O="CloudFlare, Inc.", CN=CloudFlare Inc ECC CA-2
2020-03-11T06:51:38.039	2020-03-11T00:00:00	2020-10-09T12:00:00	sni.cloudflaressl.com	*.pbntesting.com	C=US, ST=CA, L=San Francisco, O="CloudFlare, Inc.", CN=CloudFlare Inc ECC CA-2
2020-03-11T06:51:38.039	2020-03-11T00:00:00	2020-10-09T12:00:00	sni.cloudflaressl.com	*.pbntesting.com	C=US, ST=CA, L=San Francisco, O="CloudFlare, Inc.", CN=CloudFlare Inc ECC CA-2