We host sites for multiple companies and sites are hosted with custom domains. For Example
We have complete control on hosted site but do not have control over "CompanyX.com" or "CompanyY.com" and emails of these domains. These companies add CNAME DNS entries for sites that we host.
Tried to search little bit and as per this link https://support.comodo.com/index.php?/comodo/Knowledgebase/Article/View/791/0/
"We look for the file at every valid Authorization Domain, i.e. we start with the FQDN and then we will strip one or more labels from left to right in the FQDN and will look for the file on each intermediate domain."
They have said that they will strip labels and look for files on each intermediate domain. But we don't have access to web servers of "CompanyX.com" or "CompanyY.com".
Is there any way, we can complete DCV (for news.CompanyX.com single domain certificate) on our own without contacting CompanyX or CompanyY.