How BCM finds the database

There are two parts to this.
One is the Outlook Mail profile. It specifies a database name and host (computer).

The other is the registry. In
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Business Solutions eCRM
there are two pertinent keys: SQLInstanceName and SQLPort

All BCMs on a machine will use those values.

It appears that only one of the values is relevant depending on the host. If connecting to a database on the same machine, the SQLInstanceName value is used to locate the correct BCM Sql Server instance. When connecting to a database on another host, the SQLPort value is used, since only one instance will be listening on that TCP port the Sql Server instance's name is irrelevant.

In BCM v2 the default SQLInstanceName is MICROSOFTSMLBIZ and SQLPort 56183.
In BCM v3 the default SQLInstanceName is MSSMLBIZ and SQLPort 5356.