Exchange 2000 supports the basic scenario of one connection to a
single calendar domain of one partner system.
The following scenarios are also supported by Exchange:
A single Calendar Connector, at a single administrative group,
with one connection to each supported partner system.
Multiple administrative groups, each with its own Calendar
Connector, connected to the same partner system.
A single Calendar Connector that queries users on an upstream
domain.
The following scenarios are not supported by Exchange:
Multiple Calendar Connectors within a single administrative
group connected to any partner system.
Free and busy switching or querying from one partner system to
another using Exchange as a backbone. In addition, you cannot use a
partner system as a backbone between two Exchange systems.