You are prompted for the user name and the password when you try to connect to a Web folder by using a NetBIOS name on a computer that is running Windows Vista

When you try to connect to a Web folder by using a network basic input/output system (NetBIOS) name on a computer that is running Windows Vista, you are prompted for the user name and the password.

This issue occurs even though the "Automatic logon with current user name and password" security option is set for the fully qualified domain name (FQDN) of the Web folder in the "Trusted Sites" zone and in the "Local intranet" zone.

For example, this issue occurs when you use one of the following NetBIOS names to connect to the Web folder:

• http://server_name/webdav
• http://server_name.company_name.com/webdav

Note You do not experience this issue in Microsoft Windows XP.

This issue occurs because the Web Distributed Authoring and Versioning (WebDAV) redirector uses Windows HTTP Services (WinHTTP) instead of the Windows Internet (WinInet) API.

To resolve this issue, follow these steps:

1. Start Internet Explorer.
2. On the Tools menu, click Internet Options.
3. Click the Connections tab, and then click LAN settings.
4. Click to select the Bypass proxy server for local addresses check box in the Proxy server area, and then click OK two times.

In Windows Vista, the WebDAV redirector uses the automatic logon (auto-logon) policy to connect to a Web folder. Additionally, the WebDAV redirector sets the security level of the auto-logon policy to WINHTTP_AUTOLOGON_SECURITY_LEVEL_MEDIUM.

In a non-proxy network configuration, WinHTTP will not use default credentials when the WebDAV redirector sets the security level to WINHTTP_AUTOLOGON_SECURITY_LEVEL_MEDIUM. This is true for the NetBIOS name and for the FQDN.

WinHTTP does not check Internet Explorer zone information. However, WinHTTP relies on the Internet Explorer proxy settings that the WebDAV redirector sets to determine whether default credentials are used.


In Internet Explorer, you are not prompted for the user name or the password when you use the NetBIOS name to connect to a Web folder. This is because Internet Explorer looks for a period character (.) in the host name. If a period character is not present in the host name, Internet Explorer considers the host name to be located in the "Local intranet" zone.