What are the default “automatic logon” settings for the Local intranet and Trusted sites zones?
Automatic logon with user name and password is enabled, by default, in the Medium, Medium-low, and Low security settings. This setting is disabled, by default, in the High security setting. The Local intranet zone is configured, by default, to use the Medium-low security setting, and the Trusted sites zone, is configured, by default, to use the Low security setting.