some doubt about files:sqlnet, listener, so on

Hi,

do you know the meaning each this row?

listener:

# listener.ora Network Configuration File: /u01/app/oracle/product/11.2.0/db_1/network/admin/listener.ora

# Generated by Oracle configuration tools.

LISTENER =

(DESCRIPTION_LIST =

(DESCRIPTION =

(ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC1521))

(ADDRESS = (PROTOCOL = TCP)(HOST = test)(PORT = 1521))

)

)

ADR_BASE_LISTENER = /u01/app/oracle

tnsnames:

# tnsnames.ora Network Configuration File: /u01/app/oracle/product/11.2.0/db_1/network/admin/tnsnames.ora

# Generated by Oracle configuration tools.

DB11G =

(DESCRIPTION =

(ADDRESS = (PROTOCOL = TCP)(HOST = test)(PORT = 1521))

(CONNECT_DATA =

(SERVER = DEDICATED)

(SERVICE_NAME = db11g)

)

)

sqlnet.ora:

# sqlnet.ora Network Configuration File: /u01/app/oracle/product/11.2.0/db_1/network/admin/sqlnet.ora