How to safely upgrade the OS on a RODC in a DMZ

Question

Hello,
We have a Server 2008 R2 RODC in a DMZ.  I need to upgrade to Server 2012 while retaining the computer account.  I need to retain the computer account cause there a number of groups populated with users accounts in the 'Allowed RODC Password
Replication Group' and by retaining the computer account, I wont force the user accounts who authenticated on this RODC to reset their password, correct?  If I deleted the computer account during the upgrade, I'd force the users accounts who authenticated
on this RODC to reset their password due to the fact that the computer account's metadata is gone, correct?
Thanks for your help! SdeDot

Answer 1

Thanks for the response Christoffer
1. Based on the following TechNet article, is the way to preserve the passwords one of the following methods?
If you remove an RODC by using the Active Directory Domain Services Installation Wizard, you do not specify whether to retain domain controller metadata, and you are using a delegated RODC administrator account that is not a member of the Domain Admins
or Enterprise Admins groups, you can click Yes to remove AD DS without removing metadata when you are prompted to do so......
http://technet.microsoft.com/en-us/library/cc835490(v=ws.10).aspx
2. Because of Firewall rules, I will use the same IP/FQDN as the current RODC which has 2008 R2 installed, however I re'IP/Rename another freshly built Server 2012 R2 Server with the current.  I DCPromo the current RODC to a member server and rename
it to a temp IP/Name so I can use it on the new Server 2012 R2 server.
3. Based on 2, Im not doing an In-place, but after I DCPromo down the current RODC, I reIP/rename the current to a temp, then re'IP/rename a new Server 2012 R2 server with the current, then DCpromo up.
My main concern in this process is the user passwords are retained and Im not going to force a reset of user passwords. 
Thanks in advance for your help here.
Thanks for your help! SdeDot