You can configure an Oracle Names server with logging and tracing parameters.
Log information is typically stored in the names file located in $ORACLE_HOME/network/log on UNIX and ORACLE_HOME\network\log on Windows platforms.
Trace information is stored by default in names.trc, located in $ORACLE_HOME/network/trace on UNIX and ORACLE_HOME\network\trace on Windows platforms.
In the navigator pane, expand Oracle Net Configuration > Oracle Names Servers.
Select the Oracle Names server.
From the list in the right pane, select Configure Server.
Select the Advanced tab.
Adjust the logging and tracing settings.
Choose File > Save Network Configuration.