There is NO physical limit in Windows NT 4.0.

As you add users, groups, and computers to a domain, the size of the SAM (Security Accounts Manager) database increases, affecting performance. If you have a computer which acts as a domain controller (with no other major NT services running, such as File & Print, RAS, DHCP, WINS, DNS, SQL, SNA, and Exchange), you can use the following table as a guideline:

<b>
Number    SAM   Registry         PagedPool      CPU          Paging    RAM
of users  size  size             size           needed       file size

10,000     15      25 (default)   50 (default)  P or A         128      64
15,000     20      30             75            P or A         128      64
20,000     30      50            100            P or A         256     128
30,000     45      75            128            P or A         332     166
40,000     60     102            128            SMP            394     197
50,000     75     102            128            SMP            512     256
60,000     80     102            128            SMP            1Gb     512</b>
As the size of the domain increases, monitor:

* System Boot time, which increases as the system pages in the entire account database.

* Time to create a group, which increases as the total SAM size grows very large.

* Time to add users to a large group, which increases as the SAM grows above 60 MB.

* Bandwidth required to replicate a large SAM.

NOTE: P=Pentium, A=ALPHA, SMP=Multi-Processor.

NOTE: Add RAM to improve performance.

NOTE: Processor speed only becomes important as you add other services and functions.

NOTE: Add RAM as you add services and functions.

NOTE: Add RAM as you add services and functions.

NOTE: Add RAM as you add services and functions.

NOTE: Add RAM as you add services and functions.

NOTE: Add RAM as you add services and functions.

NOTE: Add RAM as you add services and functions.