I am replacing the server in our branch office and taking it as an opportunity to reconsider our domain topology. Considerations are:
Users may wish to share some files
Would like to streamline user admin/security
Would like to host all users' mailboxes on single Exchange server
What other functionality or advantages could clever design at this stage give us?
Main site uses Server 2008R2. Branch Office will have Server 2012. I could upgrade main site to 2012 if necessary.
Sites are joined by VPN.
- Domain Controller
- Global Catalog
- Exchange Server (MBX, CAS, HT roles)
If you use 2012 server in the branch site you will be required to do a Forest/Domain prep so that your 2008R2 DC can communicate. You do not have to raise the functionality but required to do a forest/domain prep.
I would also recommend that if you are hosting Exchange in this branch office you will want to have 2 DC's in there for site resiliency as the users will not be able to retrieve mail if your DC goes down at the site.
File Sharing or admin/security does not require a DC to be in the same site as it can look to another site for authentication.
One other thing to take into consideration is that if you upgrade your DC in your branch site you will also require USER CAL's for all of the users that will be authenticating to the DC. This is something that you will want to take into consideration as it is an extra cost factor.
Forest/Domain Prep for 2012 - http://social.technet.microsoft.com/wiki/contents/articles/13422.manual-schema-upgrade-for-windows-server-2012windows-server-2012-r2.aspx