Mixed Server Domain

Posted on 2011-10-10
Last Modified: 2012-05-12
I am making preparations to upgrade our primary domain controller to Windows Server 2008 R2 and am finding that I have questions that I can't seem to find answers to.

If I upgrade my PDC to Server 2008 R2 and have 3 other Server 2003 machines as BDCs, can the 3 Server 2003 machines be used to support a full featured Windows 7 Workstation environment with Roaming Profiles?

Keeping in mind that hose Server 2003 Servers will eventually be phased out in favor of Server 2008 R2 machines, are there any disadvantages that are great enough that I would be better off to upgrade the operating systems on all servers now?

When it comes to Active Directory, I have never set up a mixed Domain like that before.  I suppose I would like to discuss what the disadvantages of the Mixed Server Domain are, compared to making a full switch to a pure Server 2008 SR2 Domain...
Question by:KCU1
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    Expert Comment

    you can't get the full benfits of Win 2008 domain until all domain controllers are on Win 2008. You can run a mixed envirnment, I did for about a year, but you have to prepare the forest first with forest prep before you add a Win 2008 box on the domain as a DC. Here's a thread so you dan read more about that:

    You must also know/transfer your FSMO roles accordingly:

    Author Comment

    So eventually, once all of the Server 2003 Domain Controllers are gone, I can then upgrade Active Directory and gain full benefits of Server 2008?

    I'm also running multiple other servers (Exchange 2010, Microsoft TMG, MS SQL, etc...).  Can you think of anything I should research regarding those other servers that will help the transition go smooth?

    Does it matter if the Server 2008 Domain Controller is 64-bit, while the Server 2003 Domain Controllers are only 32-bit?
    LVL 15

    Expert Comment

    32bit verses 64 bit does not matter & yes once the 2003 DCs are gone, you can take full advantage of the Win 2008 DC featrures such as read only DCs, etc. When a Win 2008 DC is introduced to an AD forest the environment will funtion at the lowest level, meaning if a Win 2003 DC is on there, you will have those features. As far as making other things run smooth, All looks fine except I have heard others having issues when messing around with Exchange 2010 but I have no experience in that area, or not enough to feel comfortable giving advice on. Hope this helps.
    LVL 24

    Accepted Solution

    You cannot take full advantage of win2008 DC  in mixed environment.For example if you want to deploy different Password policy you cannot do the same in mixed environment,but if all the DC 2008 you can.

    There are a couple of very important considerations, that you should have in mind, before you proceed with your migration scenario.
    --Check, and raise, if necessary, the Domain and Forest functional levels. You cannot upgrade directly from Windows 2000 mixed, or Windows Server 2003 interim domain functional levels.

    --The first Windows Server 2008 Domain Controller in the forest must be a Global Catalog Server, and it cannot be a Read Only Domain Controller, RODC.

    --Check the FSMO roles assignments. When you prepare the existing AD, you should run adprep /forestprep on the Schema operations master, and adprep /domainprep /gpprep on the infrastructure master.In your case as there is a single Dc you need to run on the same server.

    The installation of Windows 2008 into the domain and migration is quite simple.
    First you need to Adprep your 2003 Domain by running
    adprep /forestprep    and
    adprep /domainprep   and
    adprep /gpprep

    from the 2008 DVD on the Windows 2000 DC  - adprep is in the SOURCES folder on the DVD.

    Next install 2008 server on the new machine. You need to assign the 2008 new computer an IP address and subnet mask on the existing network. Make sure that the preferred DNS server on new machine points to the existing DNS Server on the Domain (normally the existing domain controller)

    Join the new 2008 machine to the existing domain as a member server

    From the command line promote the new machine to a domain controller with the DCPROMO command from the command line Select "Additional Domain Controller in an existing Domain"

    Once Active Directory is installed then to make the new machine a global catalog server, go to Administrative Tools, Active Directory Sites and Services, Expand, Sites, Default first site and Servers. Right click on the new server and select properties and tick the"Global Catalog" checkbox. (Global catalog is essential for logon as it needs to be queried to establish Universal Group Membership)

    If necessary install DNS on the new server. Assuming that you were using Active Directory Integrated DNS on the first Domain Controller, DNS will automatically replicate to the new domain controller along with Active Directory. Set up forwarders as detailed at

    You must transfer the FSMO roles to the 2008 machine then the process is as outlined at

    Change all of the clients (and the new 2008 DC itself), to point to the 2008 DC for their preferred DNS server this may be in DHCP options or the TCP/IP settings.

    You can then transfer any data to the new server

    Before removing the old DC from the domain, run DCPROMO on it to remove Active Directory.

    Reference article:

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