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Current Environment

Domain Windows 2003

DNS server in DMZ (Standalone DNS server?)

File and Exchange (2003) servers in separate network

Users - 100

Near Term Plan Upgrade all servers (including Exchange) to Windows 2012

Issue:

Im not sure of the correct upgrade path but I see a couple possibilities but I dont know which is the best approach:

-       Option 1- Install Fresh 2012 Domain Configure Accounts Security and then add PC`s / users to domain and deal with all the data/email migration. Taking DNS server out of DMZ and install with AD Server / Services

or

-       Option 2a - Migrate/Transition/Upgrade to Server 2008 R2 Domain and to Exchange 2010 - keeping DNS in DMZ

-       Option 2b then further transition/migrate to Windows Server 2012 and Exchange 2013 (plan to do is Option 1 is not viable)

Current Consideration / thinking - Keeping DNS server in DMZ

Im considering doing option 2a first in order to stabilize / add capacity (to) the Network in general and to buy time to better plan Option 1 (preferred-for too many reasons to explain here).

Im not sure the best way to ask my question(s) but I will try (it will be a bit clunky):

In System properties, the computer name is showing as ex. ComputerName.DomainName.local  Up until working on this network, I have always seen ex. ComputerName.DomainName so Im a bit unfamiliar with this scenario

What is the best thing to do?

Keep the DNS in the DMZ configuration? Or as part of the upgrade have AD and DNS on the same server? (Option 1)

If I configure AD and DNS on the same server how will this affect the users PC and the user Profile? By this I mean ex. Prior to upgrade `John` has a pc named HappyPC.DomainName.local . Can John logon the upgraded Network without any problems or will his PC need to be removed from the domain (HappyPC.domainname.local) before upgrading and then re-added (to the domain. HappyPC.domain) after the upgrade and then have his profile reconfigured? 

The truth is I dont understand what happen or what will happen when taking the DNS out the DMZ. I have always worked with DNS and ADS being on the same server.

Can anyone provide some insight or advice on the best upgrade/integration approach? Or maybe some general information on what to expect when in terms with the Users profile (and email for that matter) in this scenario.  I want to make the upgrade/migration as smooth and painless as possible for the end users.

Any assistance would be appreciated.

Thank you for taking the time to read my questions.

Arlo