Your company has a main office, ten regional datacenters. and 100 branch offices.
You are designing the site topology for an Active Directory forest named contoso.com.
The forest will contain the following servers:
In each regional datacenter and in the main office, a domain controller that runs Windows Server 2012

In each branch office, a file server that runs Windows Server 2012

You have a shared folder that is accessed by using the path \\contoso.com\shares\software. The folder will be replicated to a local file server in each branch office by using Distributed File System (DFS) replication.
You need to recommend an Active Directory site design to meet the following requirements:
Ensure that users in the branch offices will be authenticated by a domain controller in the closest

regional datacenter.
Ensure that users automatically connect to the closest file server when they access \\contoso.com

\shares\software.
How many Active Directory sites should you recommend?