Think long and hard about the best Active Directory model for your organization. Do that, however, BEFORE deploying AD and Exchange 2000, said AD expert Ratmir Timashev. Changing your AD model a few months down the road can be tedious and time consuming.
Timashev concludes this series of articles on AD multi forest design by examining how to best set up multi forest environments and the messaging systems that go with them. In part one, he explained the problems administrators might have with a multi forest AD design in Exchange 2000. Timashev is president and CEO of Powell, OH-based Aelita Software.
|SWM:||What kinds of companies are most likely to setup a multi-forest environment?|
Some companies, such as financial services, insurance, healthcare and government services organizations, may need to isolate parts of their directories to meet legal requirements or to comply with business practices. For them, it will be a necessary business expense.
|SWM:||How can administrators, then, set up a multi forest environment and its messaging system?|
They should start with their AD design. First, they have to decide how to split their directories into several forests. Decentralized IT departments within a large corporation might consider separate forests to meet their individual IT needs. In addition, the most sensitive parts of the network --corporate, accounting, finance, R&D, etc. -- might be placed in a separate forest to guarantee the highest level of isolation and access control. To give users access to data in other forests, administrators create trust relationships between domains in the forests and use SID filtering, which is a mechanism that prevents the "Domain Trust" vulnerability from occurring between forests. This is a safe inter-forest collaboration setup.
|SWM:||And the messaging system?|
When you split the directory into several forests the main question you would have is whether the messaging system should be split too. In MF/SO you have a single Exchange organization shared by users from all the forests. In MF/MO each forest has an Exchange organization of its own. Having a single Exchange organization would allow for easier messaging system administration, as user collaboration and data replication is handled by native Exchange mechanisms.
|SWM:||Which AD/Exchange design is best?|
There is no "one size fits all" solution. Each organization must balance their administration and collaboration needs. However, I would expect smaller companies with a limited number of administrators to be more likely to select the single forest/single organization design. Larger organizations or organizations within certain vertical markets with unique isolation requirements are more likely to go multi forest.
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Go back to part one.