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

Results forwebmail.mu.validns.com

Logged At	Not Before	Not After	Common Name	Matching Identities	Issuer Name
2022-09-03T11:10:43.568	2022-09-03T00:00:00	2022-12-02T23:59:59	mu.validns.com	webmail.mu.validns.com	C=US, ST=TX, L=Houston, O="cPanel, Inc.", CN="cPanel, Inc. Certification Authority"
2022-09-03T11:10:42.693	2022-09-03T00:00:00	2022-12-02T23:59:59	mu.validns.com	webmail.mu.validns.com	C=US, ST=TX, L=Houston, O="cPanel, Inc.", CN="cPanel, Inc. Certification Authority"
2022-06-29T11:04:54.722	2022-06-29T00:00:00	2022-09-27T23:59:59	mu.validns.com	webmail.mu.validns.com	C=US, ST=TX, L=Houston, O="cPanel, Inc.", CN="cPanel, Inc. Certification Authority"
2022-06-29T11:04:53.917	2022-06-29T00:00:00	2022-09-27T23:59:59	mu.validns.com	webmail.mu.validns.com	C=US, ST=TX, L=Houston, O="cPanel, Inc.", CN="cPanel, Inc. Certification Authority"
2022-04-24T11:28:30.384	2022-04-24T00:00:00	2022-07-23T23:59:59	mu.validns.com	webmail.mu.validns.com	C=US, ST=TX, L=Houston, O="cPanel, Inc.", CN="cPanel, Inc. Certification Authority"
2022-04-24T11:28:28.816	2022-04-24T00:00:00	2022-07-23T23:59:59	mu.validns.com	webmail.mu.validns.com	C=US, ST=TX, L=Houston, O="cPanel, Inc.", CN="cPanel, Inc. Certification Authority"