Let me say more... this new server is to assume the same role as the old - the same domain and all that went with it. The old server uses an application that requires SQL and that application will also be upgraded on the new server - it also requiring the new SQL version, going from SQL 2005 to SQL 2012.

My first hunch is that the migration from old to new SQL might take place after the new server is added to the domain, and eventually promoted as domain controller, the old server being demoted but not removed from the domain - that at this point, is when I would move/upgrade SQL.... but then I am just assuming and don't really know yet. Thanks.