We're considering an Interforest Migration which will include multiple DCs (2003, 2008, and 2008r2, at 2003 level) and a single Exchange 2003 server.
1. Should I decommission additional DCs before the migration to the new forest, then build out additional DCs as needed?
2. We have multiple sites over VPN; do I need to create new subnets for main site and all branch sites or can I retain current network configurations?
3. Will I need a separate Exchange server waiting on the new domain/forest or can the current box migrate like the other servers/workstations?
4. Should I upgrade Exchange 2003 to 2010 at the same time or just get through the migration, then upgrade later?
5. Any special considerations for the domain-joined Hyper-V hosts?
Thanks in advance!