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

Results for*.fznu.com

Logged At	Not Before	Not After	Common Name	Matching Identities	Issuer Name
2019-02-09T16:16:53.86	2019-02-09T15:16:52	2019-05-10T15:16:52	annapolisresalefurniture.com	*.fznu.com	C=US, O=Let's Encrypt, CN=Let's Encrypt Authority X3
2019-02-09T16:16:53.86	2019-02-09T15:16:52	2019-05-10T15:16:52	annapolisresalefurniture.com	*.fznu.com	C=US, O=Let's Encrypt, CN=Let's Encrypt Authority X3
2019-02-09T16:16:52.875	2019-02-09T15:16:52	2019-05-10T15:16:52	annapolisresalefurniture.com	*.fznu.com	C=US, O=Let's Encrypt, CN=Let's Encrypt Authority X3
2019-02-09T16:16:52.875	2019-02-09T15:16:52	2019-05-10T15:16:52	annapolisresalefurniture.com	*.fznu.com	C=US, O=Let's Encrypt, CN=Let's Encrypt Authority X3