I have Asp.net website for domain A users with the Integrated Windows Authentication.
Now users from domain B need to access the website.
But Domain B users rece
Verify this by trying to add domains users from domain B to the file system where your IIS site is located.
Verify that the correct user group from domain B has access to file system where your IIS site is located. ( if not using domain users from domain B ).
Verify that the user that is testing from domain B has the correct group memberships.
And if running Kerberos authentication.
Check on client where the user is if you have a kerberos ticket by using command "klist tickets"