Reference: SteelHead RS with AWS Hybrid Cloud Storage : Branch infrastructure
  
Branch infrastructure
Branches are generally the revenue generator for most businesses. Companies must ensure that their branch operations are always up and running. In addition to protecting and securing data, they should have the ability to recover from disasters in the minimum amount of time and the least effort from personnel. Because branches and data center resources are generally located over the WAN with long distances, companies today deploy each of these services at every branch. Generally, the following services are required to keep a branch up and running:
Active Directory (AD)
Domain Name System (DNS)
Dynamic Host Configuration Protocol (DHCP)
File Server
Business Applications