Could not connect to a DATABASE with localhost as Hostname from SQL develop

Question

I am not able to connect to any Database from SQL Developer by providing "localhost" as Hostname. I could able to connect by providing the IP(192.168.1.50) of the system.
The problem here is If I am out of internet, My system does not have IP, So I am not able to connect to DB
But I need to submit a project wheere I will not have any internet. Could you please let me know how to connect to DB using localhost
Following are the listener.ora and tnsnames.ora files.
listener.ora
LISTENER =
(DESCRIPTION_LIST =
(DESCRIPTION =
(ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC1))
(ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.1.50)(PORT = 1521))
=============================
tnsnames.ora
# tnsnames.ora Network Configuration File: D:\oracle\product\10.2.0\db_2\network\admin\tnsnames.ora
# Generated by Oracle configuration tools.
ORA9 =
(DESCRIPTION =
(ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.1.50)(PORT = 1521))
(CONNECT_DATA =
(SERVER = DEDICATED)
(SERVICE_NAME = ora9)
ORA8 =
(DESCRIPTION =
(ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.1.50)(PORT = 1521))
(CONNECT_DATA =
(SERVER = DEDICATED)
(SERVICE_NAME = ora8)
EMP =
(DESCRIPTION =
(ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.1.50)(PORT = 1521))
(CONNECT_DATA =
(SERVER = DEDICATED)
(SERVICE_NAME = emp)
ORCL =
(DESCRIPTION =
(ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.1.50)(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)
Thanks in advance,
Srini

Answer 1

Oracle always uses DNS.
DNS consults the local host file.
Try in a command box
ping localhost
This should work.
If this doesn't work you need to edit
%WINDOWS%\'systems\drivers\etc\hosts
The first line needs to read
127.0.0.1 localhost
Sybrand Bakker
Senior Oracle DBA