The major benefits of Samba are stability, scalability, reliability, freedom from licensing fees; and a shorter time between problem identification and resolution.
With use of Samba as a Domain Controller the administrator can chose what authentication back-end he wants to use. That back-end can be:
This greater choice of authentication back-end means that even sites that have very poor wide area connectivity can still enjoy the benefits of centrally-managed authentication and control.
Not directly related to the question are some other features that make Samba 3.0.0 a VERY attractive facility:
Samba today is largely a Windows NT 4-style domain controller that has the ability to grow with your needs. The use of LDAP as the authentication back-end lends to Samba a high degree of flexibility and manageability.
This was first published in February 2003