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oryxway390's avatar
oryxway390
Brass Contributor
Sep 29, 2022
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Domain Controllers in Azure

Can I build a domain controller in Azure and sync it to OnPrem? Is this the best way if we slowly want to move out of On-Prem or should there be a migration strategy of moving On-Prem DC to Azure?  ...
  • LainRobertson's avatar
    Sep 30, 2022

    oryxway390 

     

    The answer can be yes or no depending on exactly what you're asking, but reading between the lines - and given you have posted a second question asking about an on-premise application - I feel like you're in the "no" camp.

     

    Explaining "yes"

    Technically, you can host a domain controller in Azure as a virtual machine (i.e. an IaaS deployment.) However, apart from being located in a Microsoft datacentre, there's no architectural change and does not specifically benefit your desire to go cloud-only.

     

    Independent of whether you host your domain controllers on on-premise hardware or on Azure IaaS, you'll still have to have the usual things like Azure AD Connect synchronising account and groups from your on-premise domain controllers over to your Azure tenant - Azure IaaS does not change this model.

     

    Which leads us to the "no" explanation.

     

    Explaining "no"

    The primary driver underpinning the "no" answer isn't actually which "joining" model you wish to pursue, since it is possible (with caveats, naturally) to operate a hybrid environment (i.e. both AD and AAD) while only using Azure AD joining. Rather, the primary driver are the on-premise applications you run.

     

    I've already provided a generic overview in your other question but to summarise here:

     

    • If your applications have some kind of direct or indirect dependency on Windows-integrated authentication at the device level, then you cannot do either of the following:
      • Go purely with Azure AD device joining;
      • Go cloud-only (i.e. you'll still need your AD forest + AAD Connect);
    • If your applications only target user accounts for Windows-integrated authentication, then:
      • You may be able to avoid hybrid-joining devices and go straight to a pure Azure AD joining model (with caveats mentioned in the other article);
      • You still need the on-premise AD + AAD Connect, meaning for as long as those applications are around, you cannot go cloud-only.

     

    Although I linked this article in the other post, for completeness, here it is again - bookmarked at the best section for the application discussion.

     

     

    Circling back to domain controller placement

    Where the domain controller is placed (Azure IaaS or on-premise) does not change anything for you. You can move them to Azure IaaS if you want to avoid managing your own on-premise hardware but the fundamental architecture isn't profoundly different and won't help you reach a cloud-only implementation.

     

    Similarly, domain controller placement has nothing to do with choosing between hybrid- or Azure AD-joining.

     

    Potential alternative to domain controllers (and therefore on-premise AD)

    You may want to look into Azure Active Directory Domain Services. Like anything halfway useful in Azure, you have to pay extra for it, but it may allow your remaining on-premise applications to operate successfully while providing you with a pathway to decommissioning your on-premise AD earlier than you otherwise would be able to.

     

     

    Cheers,

    Lain

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