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

Results forwww.ocsp-stg.digsigtrust.com

Logged At	Not Before	Not After	Common Name	Matching Identities	Issuer Name
2018-09-14T04:27:14.399	2018-08-22T15:45:46	2020-08-21T15:45:46	ocsp-stg.digsigtrust.com	ocsp-stg.digsigtrust.com	C=US, O=IdenTrust, OU=TrustID Server, CN=TrustID Server CA A52
2018-08-22T15:45:47.647	2018-08-22T15:45:46	2020-08-21T15:45:46	ocsp-stg.digsigtrust.com	ocsp-stg.digsigtrust.com	C=US, O=IdenTrust, OU=TrustID Server, CN=TrustID Server CA A52
2016-10-11T10:49:58.845	2015-09-01T19:48:47	2018-08-31T19:48:47	ocsp-stg.digsigtrust.com	ocsp-stg.digsigtrust.com	C=US, O=IdenTrust, OU=TrustID Server, CN=TrustID Server CA A52
2016-10-02T03:26:28.043	2009-10-30T16:56:36	2012-10-29T16:56:36	ocsp-stg.digsigtrust.com	ocsp-stg.digsigtrust.com	C=US, O=Digital Signature Trust Co., OU=TrustID Server, CN=TrustID Server CA A5
2016-10-01T22:38:40.488	2012-09-13T20:44:29	2015-09-13T20:44:29	ocsp-stg.digsigtrust.com	ocsp-stg.digsigtrust.com	C=US, O=IdenTrust LLC., OU=TrustID Server, CN=TrustID CA A51