NIS+ cannot distinguish between a human principal and a workstation principal when requests are made. Therefore, all user names must be different from machine names in the same namespace. In other words, within a given namespace, no user can have the same user name as a machine name, and no machine can have the same name as any user ID.
For example, under NIS it was acceptable to have a user with the login name of irina whose local machine is also named irina. Her network address would be irina@irina. This is not allowed under NIS+. When the site is converted to NIS+, either the user will have to change her login name or her machine name. Identical user and machine names are a problem even when the machine with the duplicate name does not belong to the user with the same name. The following examples illustrate duplicate name combinations not valid with NIS+:
jane@jane in the same namespace
patna@peshawar and rani@patna in the same namespace
The best solution to this problem is to check all /etc files and NIS maps before you use the data to populate NIS+ tables. If you find duplicate names, change the machine names rather than the login names, and later create an alias for the machine's old name.