The next major release of the Windows NT operating platform, code-named "Cairo," will further enhance the Windows NT Server Directory Services model. This model will provide a hierarchical structure scaling easily from small to large organizations. All domain controllers will hold master copies of the SAM database.
To accommodate phased migration, the design of the Cairo domain model will allow interoperability with existing Windows NT domains from day one. Windows NT domain accounts can be migrated to Cairo as business needs dictate.