Windows 2012 R2 -- multiple DC upgrades ?

I have three sites and three DCs

Which of the below options do
you recommend for site #1 and why ?
=========================================
Option #1
 1. install new Windows 2012 R2 server
 2. demote old server
 3. change other two sites so AD
    replicates to this new name/IP
 4. wait a few weeks, repeat for site #2
 5. wait a few weeks, repeat for site #3
=========================================
Option #2
 1. install new Windows 2012 R2 server
 2. demote old server
 3. change new server name/IP to match old info
 4. change NOTHING at other two sites since
    AD replication will continue to work
 5. wait a few weeks, repeat for site #2
 6. wait a few weeks, repeat for site #3
finance_teacherAsked:
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Ravi AtreyCommented:
Hi,

Whenever an AD upgrade needs to be done, then first thing to do that:

1. Make your forest prepare and then ad prepare so schema can be ready to get upgraded.
2.  Make your existing DC compatible with higher version of OS.  (Site:1)
3. Setup AD DC with old DC.
4. Demote the old DC.
5. Keep the same name as old one.

Reset follow option: 2.

Why to do this, as AD upgrade requires it's schema to be upgraded first so that objects, OUs gets upgrade and can listen requests from lower or similar version of AD.

For more info, check below link:

http://blogs.technet.com/b/canitpro/archive/2014/05/28/step-by-step-active-directory-migration-from-windows-server-2008-r2-to-windows-server-2012.aspx

-
Ravi
Ravi AtreyCommented:
Correction::

1. Make your forest prepare and then ad prepare so schema can be ready to get upgraded.
2. Promote your 2012 server as DC.
3. Transfer the FSMO role.
4. Demote the old DC.

http://blogs.technet.com/b/canitpro/archive/2014/05/28/step-by-step-active-directory-migration-from-windows-server-2008-r2-to-windows-server-2012.aspx

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Windows Server 2012

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