Plesk for Windows uses the IIS HTTP Server (http://www.iis.net/) for hosting and managing websites.
The default IIS configuration is defined by the hosting provider using IIS tools such as IIS Manager. The default configuration is applied to all websites on the server. However, a number of configuration parameters can be changed for individual websites right in the Plesk UI.
Website owners may need custom web server capabilities that are not provided by the default configuration. For example, unusual types of index files or the restricted access to the site by IP address.
You or site owners can configure web server settings for a website by specifying IIS settings in the Customer Panel. The custom website configuration overrides the default configuration. For details about custom IIS configuration, see Adjusting IIS Settings for Websites.
You or site owners can customize IIS configuration for a particular website in the Customer Panel in Websites & Domains > select a domain > IIS Settings. All the settings are divided into three groups:
The section Common settings contains the settings that website owners typically want to adjust. For example, to add custom index files or allow directory browsing. For each parameter, you can either type a custom value, or use the default IIS configuration (by selecting the Default value).
The settings in the section Directory security settings allow you to enforce HTTPS connections and to prohibit anonymous access to the site.
The settings in the section Access restriction settings allow you to control access to the website by IP addresses.
Note: As opposed to other web server settings, the Deny access to the site parameter does not override but supplements the list of IP addresses provided in the default configuration. In case of a conflict (for example, when you allow the address that is denied in the default configuration), your values will be used.