Protecting Network with Server and Domain Isolation

If you would like to add another layer of protection to your current security model, a server and domain Isolation solution based on Internet Protocol security (IPSec) and Active Directory can allow your network administrators to control the network environment and enhance security by isolating logical networks based on policy. This is beneficial in the sense that it creates an additional layer of policy-driven protection. to protect your network against certain network attacks.

Microsoft TechNet has tons of information on this topic online, including case studies.