How to develop Forms Authentication

Hello,


I have a common requirement but I am not sure how to do this.
Develop Forms Authentication using Active Directory (If the user exists in AD, AD being configured to SQL, I need to authentication ths user through Forms Authentication.
Secondly, If the User doesnot exist in AD, I need to directly authenticate through SQL Database using FOrms Authentication.
Both the SQL and AD are on a different server ( not local). Please help me how to achieve this.


Thanks,
Smith

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