Each complete MS DTC installation coordinates the two-phase commit protocol with its local SQL Server. One complete MS DTC installation on the network is responsible for globally coordinating the entire transaction. This MS DTC is the commit coordinator. It instructs the subordinate MS DTCs on the network to conduct the two-phase commit protocol with their local SQL Servers and ensures that the transaction either commits or aborts on all nodes. Once it has determined the transaction's outcome, the commit coordinator informs the application of the outcome.
If a transaction begins on the client, then the commit coordinator is the MS DTC specified by the application. If the application does not specify a commit coordinator, then it uses the default coordinator specified in the client computer's local system registry (for details, see Configuring the MS DTC Client Utility.
If a transaction begins on a server, then the commit coordinator is the MS DTC that is local to that server.
In either case, the commit coordinator is the MS DTC on the node on which the transaction begins. For this reason, this node is typically referred to as the parent node.