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You cannot connect to the Internet from a Windows Vista-based computer that uses a local .pac file
Article ID: 937151 - View products that this article applies to.
When you try to connect to the Internet from a Windows Vista-based computer that uses a local proxy autoconfiguration (.pac) file, the proxy server is not detected successfully. Therefore, you cannot connect to the Internet.
By default, in Windows Vista, the Network Connectivity Status Indicator (NCSI) feature tries to determine whether you are connected to the Internet or to a smaller network. Before NCSI can report on Internet connectivity, NCSI must verify the connection to the proxy server. To do this, NCSI uses the WinHTTP feature to find the proxy server. However, WinHTTP is unable to process locally stored .pac files. Because NCSI cannot find the proxy server, the Windows Vista-based computer is reported as having only local connectivity.
Other Windows features may also be affected by this limitation unless they can access the Internet without identifying a proxy server.
To resolve this issue, you can use one of the following methods.
Method 1: Use the Web Proxy Autodiscovery (WPAD) protocolThe WPAD protocol lets Windows Vista-based computers automatically discover proxy servers on the network. For more information about the WPAD protocol, visit the following Microsoft Web site:
http://technet.microsoft.com/en-us/library/cc713344.aspxFor more information, visit the following Internet Engineering Task Force (IETF) Web site:
http://www.ietf.org/Microsoft provides third-party contact information to help you find technical support. This contact information may change without notice. Microsoft does not guarantee the accuracy of this third-party contact information.
Method 2: Use the netsh command to manually specify the proxy serverNote The netsh command is independent of the proxy settings that are specified in Microsoft Internet Explorer. After you set the proxy server by using the netsh command, you must still configure the Internet Explorer proxy settings by using the Local Area Network (LAN) Settings dialog box.
How to manually set proxy settingsIf you manually set the proxy settings by using the Local Area Network (LAN) Settings dialog box in Internet Explorer, you may experience the following limitations:
Article ID: 937151 - Last Review: October 31, 2007 - Revision: 1.6