Register a subdomain name in a customer tenant
You will need to create a unique, fully qualified subdomain name for every customer.
In this example, we will create a subdomain 'sbc1.customers.adatum.biz' in a tenant with the default domain name 'woodgrovebank.us'. All actions below are in the customer tenant.
Ensure that you have appropriate rights in the customer tenant.
You can only add new domains if you signed in to the Microsoft 365 admin centre as a Global Administrator.
To validate the role you have, please sign in to the Microsoft 365 admin centre (https://portal.office.com), go to Users > Active Users, and then verify that you have a Global Administrator role.
For more information about admin roles and how to assign a role in Microsoft 365 or Office 365, see About admin roles.
Admin Center URL: https://admin.microsoft.com | Teams Admin URL: https://teams.admin.microsoft.com
