Hope this helped you better understand setting up using
Membership providers with forms authentication, especially Active Directory
Membership Provider with Authorization manager. Forms authentication is the
default choice when it comes to authenticating users from internet and if those
users are your domain users as well, combining these technologies can allow you
to authenticate a user very efficiently without having to expose your active
directory to public internet.
Please feel free to send me your comments and suggestions
via the feedback link. I would most certainly appreciate it.