I created a sub site with unique permission and If I add a AD Domain security group to SharePoint group(that has Read Permission level) and If I try to login with user in that Group I get ACCESS DENIED error.
But if I add the user directly with Read permission he is able to access the site.
The domain AD group is not Distribution group.
Is it something to do with User Profile Synchronization or is there any specific settings in AD Security Group that is preventing the group from accessing the site???