select * from global_name; returns MONY

in init.ora, global names= true

db_domain is NULL in init.ora.

under this situation, I created database link using the following syntax.

create database link MONY
connect to (username) identified by (password)
using 'Service name';

when I try to issue the following test query
select * from dba_users@database_link_name

Oracle gave me the
ora 02085 Database link MONY.world connects to MONY.

Since the value of db_domain is NULL, I don't think that I need to append '.WORLD' after MY database_link_name. If my db_domain is WORLD, I should put '.WORLD' after the database_link_name.
what do you think?