This will be a super short post, because this task is super easy!
My lab in Azure wouldn’t be complete without its own custom domain. Honestly, this is one of those “just pop over to the Portal” tasks because it only takes a few clicks, particularly if you are only doing it once. But you won’t be able to complete in a hurry, because your registrar will update the public DNS entries on their own sweet time and that update is needed to complete the process.
By the way, if you really want to do this without the Portal, you can find information on installing the right PowerShell modules and the commands here. (http://msdn.microsoft.com/en-us/library/azure/jj151815.aspx) If you are going to managing multiple tenants over time, PowerShell will likely be the best way to go.
Anyway, when you are in the Portal, click “Active Directory” in the navigation. Select the domain directory you want to add a custom domain to. In this case, I wanted to create a new Azure Directory for the Imperfect Lab, so I clicked “New” and then went to APP SERVICES -> ACTIVE DIRECTORY -> DIRECTORY -> CUSTOM CREATE.
I named my directory “ImperfectLab” and picked my region. The domain name for the directory is now “Imperfectlab.onmicrosoft.com”. Since I don’t want to be using the “onmicrosoft.com” moniker for very long, I need to add my recently purchased domain. You actually have to a own (or at least control) the domain you want to add because it’s requirement to add a TXT or MX record to your public DNS.
Click into the directory you want to use and go to the “Domains” section. On the bottom action bar, click “Add”. Then type in the FQDN for your “real” domain, in my case “imperfectlab.com”. You be given the information to create either at TXT or MX record that needs to be added to your DNS records managed by your registrar.
My registrar doesn’t accept the @ symbol for the parent zone, but leaving that field blank worked fine. You have to add the record, wait for the external DNS to update and then return to the portal to verify it.
Once verified, you can create (or sync) users into your Azure Active Directory using either your “email@example.com” UPN or your “firstname.lastname@example.org” UPN.