adding_loopback_adapter.htm
Disclaimer: Do it at your own risk.

It  is pre-installation requirement of an Oracle DBMS, in windows environment. It basically generate a local IP address to virtual network adapter as a primary adapter. Oracle installer uses this adapter, while other applications would use your hardware-network card in a windows network-management system.
1. Open Control Panel, then Click On Add hardware
2.Follow the Wizard:

3.Choose the first option:
4.Select "Add a new hardware device"

5.Check on the second option:

6.Adding virtual Network Adapter:

7.Use Microsoft Loop Back Adapter
8.Start installing the virutal-harware
9.If all goes well, you will get a screen similar to this one.
10.You will have Microsoft Loop Back Adapter listed in Network Connections.
11. Note two local connection, when loop back is added you will note the followings'

Ethernet adapter Local Area Connection 5:

Connection-specific DNS Suffix . :
Description . . . . . . . . . . . : Microsoft Loopback Adapter
Physical Address. . . . . . . . . : 02-00-4C-4F-4F-50
Dhcp Enabled. . . . . . . . . . . : Yes
Autoconfiguration Enabled . . . . : Yes
Autoconfiguration IP Address. . . : 169.254.25.129
Subnet Mask . . . . . . . . . . . : 255.255.0.0
Default Gateway . . . . . . . . . :
12.Check on Listener status:

13.execute netstat -a in a command window, and

14. after adding loop back  system/manas8 pass word.
15.Displaying Enterprise Manager (Don't forget to reset that PWD at an interval of 180 days) .
15. Current *.ora files, tcp.ip will differ as we use different internet providers, below given with at&t and comcast cable connection in xp-home/apache2.0/, with enabled loop back adapter, MYSQL,

# listener.ora Network Configuration File: C:\oracle\product\10.2.0\db_1\network\admin\listener.ora
# Generated by Oracle configuration tools.
#(ADDRESS = (PROTOCOL = TCP)(HOST = MANAS8X)(PORT = 1521))
#(ADDRESS = (PROTOCOL = TCP)(HOST = 198.168.2.10)(PORT = 1521))
#192.168.1.65
#(ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.1.65)(PORT = 1521))

SID_LIST_LISTENER =
(SID_LIST =
(SID_DESC =
(SID_NAME = PLSExtProc)
(ORACLE_HOME = C:\oracle\product\10.2.0\db_1)
(PROGRAM = extproc)
)
)

LISTENER =
(DESCRIPTION_LIST =
(DESCRIPTION =
(ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC1))
(ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.1.65)(PORT = 1521))
)
)

---------------------------------------

# tnsnames.ora Network Configuration File: C:\oracle\product\10.2.0\db_1\network\admin\tnsnames.ora
# Generated by Oracle configuration tools.
#192.168.1.65
#(ADDRESS = (PROTOCOL = TCP)(HOST = 198.168.2.10)(PORT = 1521))
#(ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.1.65)(PORT = 1521))
ORCL =
(DESCRIPTION =
(ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.1.65)(PORT = 1521))
(CONNECT_DATA =
(SERVER = DEDICATED)
(SERVICE_NAME = orcl)
)
)

EXTPROC_CONNECTION_DATA =
(DESCRIPTION =
(ADDRESS_LIST =
(ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC1))
)
(CONNECT_DATA =
(SID = PLSExtProc)
(PRESENTATION = RO)
)
)