Symptom
When DHCP/NetBoot is turned on in Server Settings (version 10.2 or later) or Server Admin (version 10.1.5 and earlier), UIDs 100 through 149 are assigned to NBUsers 1 through 50 in the Local NetInfo Domain.
When two or more accounts have the same UID, the operating system treats them all as the same account. This can result in issues with ownership and access, such as too much access or loss of ownership.
Solution
If NetBoot will be used, assign the NBUsers different UID numbers so they will not overlap with the other users. By doing this, you avoid reconfiguring the ownership of existing home directories.
Mac OS X Server 10.2 or later automatically starts assigning UID numbers 1025 and higher to new users, so it would only be affected if the server was upgraded from an earlier version or the users were imported with pre-existing UIDs.