Azure AD DS and Office 365

Luke Cannon 1 Reputation point
2020-06-23T06:03:59.697+00:00

We have a cloud only Office 365 tenant and we have just enabled a free trial for Azure using our GA account. We are going to be running up some VMs to host some LOB applications and the VMs will need to be AD joined. I tried running up Azure AD DS but our current public domain name exceeds the 15 character limit so we are going to look into registering a new domain. Can we use this new domain as our primary domain in office 365 and as our Azure AD DS domain or do we need to use two different domains?

Microsoft Entra
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  1. Konstantin Zarudaev 86 Reputation points
    2020-06-23T08:32:42.597+00:00

    Hi,
    This limitation for NetBIOS name come from Win NT era :)
    You right, there is clear limitation:
    https://learn.microsoft.com/en-us/azure/active-directory-domain-services/tutorial-create-instance

    Domain prefix restrictions: You can't create a managed domain with a prefix longer than 15 characters. The prefix of your specified domain name (such as aaddscontoso in the aaddscontoso.com domain name) must contain 15 or fewer characters.

    To continue work with your environment you can try to install Azure AD DS with the PowerhSell and set the NetBIOS name manually.

    https://learn.microsoft.com/en-us/azure/active-directory-domain-services/powershell-create-instance

    In the last step instead of the full FQDN set it manually. For example:
    $ManagedDomainName = "domain.com"

    After you can add a UPN suffix into your AD DS servers same as a public one.

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