Windows NT Advanced Server 3.1 had a recommended limit of 10,000 users per domain. Beginning with Windows NT Server version 3.5, performance improvements, combined with the more powerful hardware now available, have significantly increased the number of users per domain. Now, as many as 40,000 user accounts can be supported in a single domain, and well in excess of 100,000 users using multiple master domains. The maximum recommended size of the Security Accounts Manager (SAM) database file (40 MB) is the determining factor for the number of users. This appendix provides job aids to assist you in calculating the size of the file, and therefore the number of user, machine, and group accounts.