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

Results forwebdisk.smsinline.com

Logged At	Not Before	Not After	Common Name	Matching Identities	Issuer Name
2018-12-12T18:56:35.302	2018-12-10T00:00:00	2019-12-10T12:00:00	smsinline.com	*.smsinline.com	C=US, ST=CA, L=San Francisco, O="CloudFlare, Inc.", CN=CloudFlare Inc ECC CA-2
2018-12-10T04:24:34.008	2018-12-10T00:00:00	2019-12-10T12:00:00	smsinline.com	*.smsinline.com	C=US, ST=CA, L=San Francisco, O="CloudFlare, Inc.", CN=CloudFlare Inc ECC CA-2
2018-12-10T04:24:32.248	2018-12-10T00:00:00	2019-12-10T12:00:00	smsinline.com	*.smsinline.com	C=US, ST=CA, L=San Francisco, O="CloudFlare, Inc.", CN=CloudFlare Inc RSA CA-1
2018-12-09T16:05:51.197	2018-12-09T00:00:00	2019-12-09T12:00:00	sni.cloudflaressl.com	*.smsinline.com	C=US, ST=CA, L=San Francisco, O="CloudFlare, Inc.", CN=CloudFlare Inc ECC CA-2
2018-12-08T15:00:32.885	2018-12-08T14:00:31	2019-03-08T14:00:31	smsinline.com	webdisk.smsinline.com	C=US, O=Let's Encrypt, CN=Let's Encrypt Authority X3
2018-12-08T15:00:31.979	2018-12-08T14:00:31	2019-03-08T14:00:31	smsinline.com	webdisk.smsinline.com	C=US, O=Let's Encrypt, CN=Let's Encrypt Authority X3
2018-11-13T06:44:21.802	2018-11-13T00:00:00	2019-02-11T23:59:59	smsinline.com	webdisk.smsinline.com	C=US, ST=TX, L=Houston, O="cPanel, Inc.", CN="cPanel, Inc. Certification Authority"
2018-11-13T06:44:01.834	2018-11-13T00:00:00	2019-02-11T23:59:59	smsinline.com	webdisk.smsinline.com	C=US, ST=TX, L=Houston, O="cPanel, Inc.", CN="cPanel, Inc. Certification Authority"