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

Results for*.www.client.harmonweb.com

Logged At	Not Before	Not After	Common Name	Matching Identities	Issuer Name
2020-07-02T17:43:33.423	2020-07-02T16:43:33	2020-09-30T16:43:33	client.harmonweb.com	*.www.client.harmonweb.com	C=US, O=Let's Encrypt, CN=Let's Encrypt Authority X3
2020-07-02T17:43:33.423	2020-07-02T16:43:33	2020-09-30T16:43:33	client.harmonweb.com	*.www.client.harmonweb.com	C=US, O=Let's Encrypt, CN=Let's Encrypt Authority X3
2020-07-02T17:43:33.291	2020-07-02T16:43:33	2020-09-30T16:43:33	client.harmonweb.com	*.www.client.harmonweb.com	C=US, O=Let's Encrypt, CN=Let's Encrypt Authority X3
2020-07-02T17:43:33.291	2020-07-02T16:43:33	2020-09-30T16:43:33	client.harmonweb.com	*.www.client.harmonweb.com	C=US, O=Let's Encrypt, CN=Let's Encrypt Authority X3