Oracle Database Discussions

I have created oracle 10g Release 1 database(orcl) in Windows Xp Professional edition through DBCA . I also created one more database(sample) manually .

The ORCL server process listens to port no 1521 and
SAMPLE server process listens to port no 1522

Once I start the OracleServiceORCL (Service for orcl) from services.msc and check the listener status it displays

Service "orcl" has 1 instance(s).
Instance "orcl", status READY, has 1 handler(s) for this service...

But when I start OracleServiceSAMPLE (Service for sample) from services.exe and check the listener status there is no change . Only when i start the instance the dynamic registration takes place with port no 1521 .

There is no entry for listener parameter in init.ora file . My question is how is the service ORCL able to get itself registered with the listener even before the instance is up ?

And how can i know which port no is linked with which server process?

Also if we provide a different port number(other than 1521 say 1522) in tnsnames.ora for a service and consider the listener is listening to both 1521 and 1522 . Now consider that port number 1521 is free . In this case to which port number will the service be listening to ?

The listener file looks like this

SID_LIST_LISTENER =
(SID_LIST =
(SID_DESC =
(SID_NAME = PLSExtProc)
(ORACLE_HOME = D:\oracle\product\10.1.0\Db_2)
(PROGRAM = extproc)
)
)

LISTENER =
(DESCRIPTION_LIST =
(DESCRIPTION =
(ADDRESS = (PROTOCOL = TCP)(HOST = irobo)(PORT = 1521))
)
(DESCRIPTION =
(ADDRESS = (PROTOCOL = TCP)(HOST = irobo)(PORT = 1522))
)
)


The tnsnames file has the following entry

ORCL =
(DESCRIPTION =
(ADDRESS_LIST =
(ADDRESS = (PROTOCOL = TCP)(HOST = irobo)(PORT = 1522))
)
(CONNECT_DATA =
(SERVICE_NAME = ORCL)
)
)

SAMPLE =
(DESCRIPTION =
(ADDRESS_LIST =
(ADDRESS = (PROTOCOL = TCP)(HOST = irobo)(PORT = 1521))
)
(CONNECT_DATA =
(SERVICE_NAME = ORCL)
)
)

EXTPROC_CONNECTION_DATA =
(DESCRIPTION =
(ADDRESS_LIST =
(ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC))
)
(CONNECT_DATA =
(SID = PLSExtProc)
(PRESENTATION = RO)
)
)