We are an Exchange 2010 site, i am doing some prep to the domain ready for an Exchange 2013 upgrade.
Just want to check i am 100% correct first, the second one just want to be sure it wont overwrite existing stuff.
First we do a setup /PrepareSchema
Then setup /PrepareAD [/OrganizationName: <Existing Exchange 2010 Org name> ]
Last setup /PrepareDomain