I've already posted tnsnames.ora and listener.ora file of client and servers. As you can see from them, the listener name(as in the connect string) orclrac is there in the listener.ora files of server nodes.

As for from which computer i'm logging in, actually i'm using vmware for rac implementation. So i'm logging in from the host operating system.

Also, i amn't getting anything from sqlnet.ora file of the client.
It looks as below.
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# sqlnet.ora Network Configuration File: f:\oracle\product\10.2.0\client_2\network\admin\sqlnet.ora
# Generated by Oracle configuration tools.

# This file is actually generated by netca. But if customers choose to
# install "Software Only", this file wont exist and without the native
# authentication, they will not be able to connect to the database on NT.

SQLNET.AUTHENTICATION_SERVICES= (NTS)

NAMES.DIRECTORY_PATH= (TNSNAMES)


Nothing has been mentioned about the policy.