Should I use the SID or Service Name when configuring an Oracle DB for Advanced Authentication?
The answer depends on how your database is configured. The Service_Name can best be described as an alias for your database. You can have multiple service names assigned to a single database which can help define different uses for the same database. The SID uniquely defines a single database and instance. If you are using an Oracle RAC cluster you will have to define a Service_Name and use that since it is required for Oracle RAC to utilize the same database across multiple server nodes. If you have configured the TNS Listener for a Service_Name then you could use that. Otherwise the SID would be just fine.
Oracles SID and Service_Names are a simple way to address an Oracle database. While there is no performance differences, it does change the syntax of the connection strings and therefore it is important to know which your database listener is configured to use.