Forum Discussion
Add subdomain to existing federated domain with Exhange Hybrid configured
That seems like another stupid limitation of the "add domain" wizard, just use PowerShell (New-MsolDomain). Although I just tested it in one of my test tenants and I was able to add a subdomain to a federated domain just fine via the portal. So perhaps it's something specific to your setup. Anyway, just use PowerShell:
New-MsolDomain -Name sub2.domain.com -Authentication federated
We want to add subdomain coworkers.company.com and currently we already have federated our company.com domain. If we add coworkers.company.com from admin center > setup > domains > add domain, it requests email address of @coworkers.company.com to complete. Furthermore, if I click okay, I've added txt record, it redirect user@coworkers.company.com to create new tenant as screenshot I attached.
Does it the right way to add subdomain of existing federated domain? Or I can just add subdomain using Azure AD powershell?
That seems like another stupid limitation of the "add domain" wizard, just use PowerShell (New-MsolDomain). Although I just tested it in one of my test tenants and I was able to add a subdomain to a federated domain just fine via the portal. So perhaps it's something specific to your setup. Anyway, just use PowerShell:
New-MsolDomain -Name sub2.domain.com -Authentication federated