OCP 1Z0 052 131

131. Which naming method uses the tnsnames.ora file to store the connect descriptor used by the client 
while connecting to the database instance from a remote machine? 
A.host naming method 
B.local naming method 
C.external naming method 
D.directory naming method 
Answer: B

This tnsnames.ora file is a configuration file that contains net service names mapped to connect descriptors for the local naming method, or net service names mapped to listener protocol addresses.

A net service name is an alias mapped to a database network address contained in a connect descriptor. A connect descriptor contains the location of the listener through a protocol address and the service name of the database to which to connect. Clients and database servers (that are clients of other database servers) use the net service name when making a connection with an application.