http://technet.microsoft.com/en-us/windowsserver/bb530956

http://technet.microsoft.com/en-us/library/cc754697.aspx

Use Active Directory Sites and Services to manage sites in an Active Directory.

• Represent physical network topology
• Defined by network subnets
• Connect sites with site links
  • Represent WAN connections between sites
• Replication within a site is automatic
• Replication between sites occurs every 3 hours by default
• Default Site named Default-First-Site-Name
• Domain Controllers installed to site
• Defining multiple sites optimizes WAN links
  • Routing
  • Replication
  • Authentication
  • Service location
• Client site assignment is determined by its IP address

• Logical Topology

http://technet.microsoft.com/en-us/library/cc794776%28WS.10%29.aspx

The Intersite Topology Generator (ISTG) is the domain controller in each site that is responsible for generating the intersite topology.

To determine the ISTG role owner for a site:

1. Open Active Directory Sites and Services
2. Click the site object whose ISTG role owner you want to determine
3. Right-click the NTDS Site Settings → Properties