You can install Microsoft Internet Security and Acceleration (ISA) Server 2004 Enterprise Edition in variations of topologies. When you configure a branch, there are two basic configuration options that you must consider:
The nature of the domain relationship between the branch office and the main office. The branch may be in the same domain as the main office, in a child domain, in a separate domain with trust between the domains, or in a workgroup.
The kind of connectivity that exists between the branch office and the main office before you install ISA Server 204 in the branch. ISA Server 204 provides secure site-to-site virtual private networking functionality between the branch and main offices. However, that functionality cannot be provided to the branch before ISA Server 204 is installed. Options for providing initial connectivity are discussed in this document.