After deciding on the domain structure model, the next step is to identify the number of domains required. The number of domains depends on the number of objects that will be managed, the number of geographical locations, administrative requirements, and the bandwidth of links.
In the following table, I have listed down the number of users that can be maintained in a domain against the replication bandwidth:
|
Bandwidth |
If 1% of bandwidth is allowed for replication |
If 10% of bandwidth is allowed for replication |
|
128kbps |
25,000 |
100,000 |
|
256kbps |
50,000 |
100,000 |
|
512kbps |
80,000 |
100,000 |
|
T1 |
100,000 |
100,000 |
Bandwidth between locations is not the only reason for multiple domains. Administrative requirements and security requirements are also valid reasons for it.
When the number of domains increases, the complexity, cost of implementation and maintenance, and the management of diverse security settings increase as well. Therefore, decide the number of domains in a meaningful manner. I have seen people create domains in places where they can achieve the same thing using an OU or some different group policies.