Priority of using TNSNAMES. ORA file in ORACLE

ORACLE uses TNSNAMES. for UNIX platforms, ORACLE first looks for the environment variable TNS_ADMIN. If the environment variable exists, it goes to the directory specified by the environment variable to find tnsnames. ora file. Otherwise, go to the $ ORACLE_HOME/network/admin directory and find it. On a WINDOWS platform, if the rule is not met, ORACLE will first find TNSNAMES in the current directory. ORA file. If this file does not exist, search for the TNS_ADMIN environment variable. If the environment variable does not exist, go to $ ORACLE_HOME/network/admin. C: \ Documents and Settings \ htaix> type C: \ oracle \ product \ 10.2.0 \ db_1 \ NETWORK \ ADMIN \ tnsnames. ora # tnsnames. ora Network Configuration File: c: \ u01 \ oracle \ product \ 11.2.0 \ client_1 \ network \ admin \ tnsnames. ora # Generated by Oracle configuration tools. dev2 = (DESCRIPTION = (ADDRESS = (PROTOCOL = TCP) (HOST = 10.192.30.28) (PORT = 1521) (CONNECT_DATA = (SERVER = DEDICATED) (SERVICE_NAME = jtcmdb ))) c: \ Docu Ments and Settings \ htaix> type C: \ tnsnames. oradev2 = (DESCRIPTION = (ADDRESS = (PROTOCOL = TCP) (HOST = 10.192.30.29) (PORT = 1521) (CONNECT_DATA = (SERVER = DEDICATED) (SERVICE_NAME = jtcmdb ))) c: \ Documents and Settings \ htaix> note that there is a TNSNAMES under drive C and directory C: \ oracle \ product \ 10.2.0 \ db_1 \ NETWORK \ ADMIN. ORA file, but the IP address of the HOST is different. One is 10.192.30.29 and the other is 10.192.30.28. Note that the current directory is C: \ Documents ents and Settings \ htaix>. C: \ Documents ents and Settings \ htaix> tnsping dev2 TNS Ping Utility for 32-bit Windows: Version 10.2.0.1.0-Production on-2013 16:34:41 Copyright (c) 1997,200 5, Oracle. all rights reserved. used parameter file: c: \ oracle \ product \ 10.2.0 \ db_1 \ network \ admin \ sqlnet. ora has used the TNSNAMES adapter to resolve the alias Attempting to contact (DESCRIPTION = (ADDRESS = (PROTOCOL = TCP) (HOST = 10.192.30.28) (PORT = 1521) (CONNECT_DATA = (SERVE R = DEDICATED) (SERVICE_NAME = jtcmdb) OK (30 ms) You Can See That ORACLEL takes precedence over TNSNAMES in the $ ORACLE_HOME/network/admin directory. ORA (the TNS_ADMIN environment variable is not configured ). Next, I will switch the current path to the C root directory and execute tnsping. C: \ Documents ents and Settings \ htaix> cd c: \ C: \> tnsping dev2 TNS Ping Utility for 32-bit Windows: version 10.2.0.1.0-Production on-2013 16:37:05 Copyright (c) 1997,200 5, Oracle. all rights reserved. used parameter file: c: \ oracle \ product \ 10.2.0 \ db_1 \ network \ admin \ sqlnet. ora has used the TNSNAMES adapter to parse the alias Attempting to contact (DESCRIPTION = (ADDRESS = (PROTOCOL = TCP) (HOST = 10.192.30.29) (PORT = 1521) (CONNECT_DA TA = (SERVER = DEDICATED) (SERVICE_NAME = jtcmdb) OK (30 ms) You can see that this IP address is changed to 10.192.30.29, using TNSNAMES. ORA under the C root directory.