listener.ora

See How to mine listener's log, Add more listeners and load balance

9i
LSNR_BSM_PRE =
  (ADDRESS_LIST =
        (ADDRESS= (PROTOCOL= TCP)(Host=db901ram)(Port= 1536))

  )
SID_LIST_LSNR_BSM_PRE =
  (SID_LIST =
    (SID_DESC =
      (ORACLE_HOME= /app/oracle/product/9.2.0)
      (SID_NAME = BSM_PRE)
    )
  )

10g
SID_LIST_LSNR_RCC_SCT =
  (SID_LIST =
    #Optional
    (SID_DESC =
      (SID_NAME = PLSExtProc)
      (ORACLE_HOME = /app/oracle/product/10.2.0)
      (PROGRAM = extproc)
    )
    (SID_DESC =
      (GLOBAL_DBNAME = RCC_SCT)
      (ORACLE_HOME = /app/oracle/product/10.2.0)
      (SID_NAME = RCC_SCT)
    )
  )

LSNR_RCC_SCT =
  (DESCRIPTION_LIST =
    (DESCRIPTION =
      (ADDRESS = (PROTOCOL = TCP)(HOST = db601rcc)(PORT = 1521))
    )
    (DESCRIPTION =
      (ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC0))
    )
  )