Allow Anonymous users but still SharePoint site popup for Credentials.

With some development part, I came across one issue, I allow Anonymous users on my site, but when I access Portal, still it gives popup for credentials..

I searched all blogs, and check setting everywhere, but unable to find the issue, then last I come across one article in TechNet (Choose security groups) and that help me to resolve the issue.

If in permission for Site in Central Admin, has Deny All; then portal will not behave as Anonymous. So I removed the Deny All permissions and it works..

Here is the article.. (Link)
 
Permission policies provide a centralized way to configure and manage a set of permissions that applies to only a subset of users or groups in a Web application. You can manage permission policy for anonymous users by enabling or disabling anonymous access for a Web application. If you enable anonymous access for a Web application, site administrators can then grant or deny anonymous access at the site collection, site, or item level. If anonymous access is disabled for a Web application, no sites within that Web application can be accessed by anonymous users.

• None No policy. This is the default option. No additional permission restrictions or additions are applied to site anonymous users.
• Deny Write Anonymous users cannot write content, even if the site administrator specifically attempts to grant the anonymous user account that permission.
• Deny All Anonymous users cannot have any access, even if site administrators specifically attempt to grant the anonymous user account access to their sites.

Hope it will help...