If you try to make a NetBoot image from a source disk image that contains more than 2.5 GB of data, your attempt will not succeed.
Network Image Utility will report the creation was successful, but it really isn't. The Network Image Utility log, which can be seen by clicking the triangle in the bottom of the window, will show error messages.
This occurs with Mac OS X Server 10.3 or later.
To resolve the issue, follow these steps: