# Oracle Client Configuration Follow these steps to configure the Oracle client: - Construct (if not available yet) a tnsnames.ora configuration file. - In a tnsnames.ora file (‘tns’ is the abbreviation for ‘Transparant Network Substrate’) all Oracle based databases (‘services’) and the route via the network to get there, are described. - An example of a description of the service:  - This one describes that on the server with IP address 192.168.172.16 on port 1521 a program runs that knows how to make a connection with an Oracle database with the SID dvt11r2 and the global name dvt11r2.invantive.com. - Full instructions on creating tnsnames.ora can be found in the Oracle documentation. - Make sure that the tnsnames.ora file is located on the same place on all PC's, preferably in way to make it easy to add services from a central location. For fixed workplaces often a network drive is used, for example, as follows:  - Open the register with ‘regedit’ and go to the key HKLM\SOFTWARE\Oracle\KEY_OraClient11g_home1:  - Add a string with the name ‘TNS_ADMIN’ and make it point to the network location:  - Change also the NLS_LANG to ‘DUTCH_THE NETHERLANDS.AL32UTF8’ to make sure that messages appear in dutch and the Unicode character set is used. If you use Oracle Instant Client, then there is no NLS_LANG in the Windows registry; that's why you need to define the NLS_LANG environment variable in Windows.  - If you use Oracle Instant Client, then there is no NLS_LANG in the Windows registry; that's why you need to define the NLS_LANG environment variable in Windows. - Test the connection from a command prompt with ‘tnsping’:  - It is still not certain if the user/password are correct, but it is certain that a network connection to the Oracle service can be built. - Finally, check the connection by logging in with SQL*Plus.