A configuration file for the client or server that specifies:
Client domain to append to unqualified service names or net service names
Order of naming methods the client should use when resolving a name
Route of connections
External naming parameters
Oracle Advanced Security parameters
The sqlnet.ora file must reside in one of the following locations:
The directory specified
by the TNS_ADMIN
environment variable If the TNS_ADMIN
environment variable is not defined as a variable on Windows NT, it may
be in the registry.
The $ORACLE_HOME/network/admin
directory on UNIX or the ORACLE_HOME\network\admin
directory on Windows operating systems.