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Warning: Internet Explorer 7 may have difficulties working with a wpad.dat file. http://msdn.microsoft.com/en-us/ie/aa740486.aspx states: "If you are on a network that uses a proxy server, and you notice slowness or a problem connecting to websites after upgrading to Internet Explorer 7, it might be due to web proxy auto-detection problems." This known issue warning then describes the steps of disabling the automatic proxy detection option and manually configuring access to your web proxy as the fix for this problem. If your users will be using Internet Explorer 7, please consider this issue before deciding on this option.
To deploy your proxy.pac file as a wpad.dat file:
Note: By default, when a connection is established through a proxy server, the hostname of the site and the proxy server name are cached. On future attempts to access the hostname in the same session, Internet Explorer has cached information about which proxy to use. Therefore, all subsequent connections to the host are tried through the proxy that was used previously. This means that if the proxy server name that is cached is unavailable during the same session, the automatic proxy configuration script is not re-processed, and you receive a "Page Cannot Be Displayed" error message in Internet Explorer. You may want to disable the Automatic Proxy Result Cache to provide the proxy redundancy that you require. This will result in client-side processing of every GET request that is issued by Internet Explorer. As a result, Internet Explorer performance may be impacted depending on the logic of the Automatic Proxy Configuration Script and its size. The procedure for doing this is documented in the Microsoft Knowledgebase article http://support.microsoft.com/kb/271361.
Once these steps are completed, your users' browser proxy configuration will be automatically updated to use the Web Appliance as their web proxy.
Additionally, you can enforce the application of automatic updates using the wpad.dat file by Creating a Group Policy Object (GPO).
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