how to use Active Directory account to authenticate using membership provider

I have a application which use membership provider to authenticate user. Now my requirment is to integrate Active Directory accounts as well to authenticate using Membership provider.  So i will need to integrate both non AD Accounts( Created using MEmbership provider) and as well Active Directory user in domain.
if some one can suggest me some steps to achieve it , Also if some can direct me to any blog that helps you define this step by step process
Please advise
 
Thank you
 
AS
 
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