Ok My question is : I didn't put domain_name = xyz.com in my init.ora but if default_domain_name in sqlnet.ora = .world then if I don't put xyz.com at the end of my service name in tsnname then it can not connect.

Do you think if I put DOMAIN_NAME = WORLD in init.ora then it will be WORLD ???

I know I am a little confuse, but please help.