Hi @Deshmukh, Vijit ,
Welcome to the Microsoft Q&A Platform. Thank you for reaching out & I hope you are doing well.
I understand that you are trying to authenticate App Service behind Azure FrontDoor using Azure AD.
Your requirement is documented in the below blog post:
https://azure.github.io/AppService/2021/03/26/Secure-resilient-site-with-custom-domain.html
Per our discussions in the comments section, you were able to get this set-up working following the above blog.
Cheers,
Kapil.
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