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IE window doesn't function with PAC file as expected after hitting any inside page on www.bbc.com RRS feed

  • Question

  • Hi,

    I am facing a wierd problem in our corporate enviornment. We use PAC file for internet access. The internet site requests are diverted to the Proxies and the intranet requests are directly accessed over the LAN using the PAC logic. This has been working fantastic for about more than 5 years now. Now suddenly we are seeing an issue while accessing the www.bbc.com website and the pages within the site.

    Once we access any page within www.bbc.com the internet explorer doesn't check the PAC file and tries to continously go directly over the LAN using DNS resolutions (i found this from wireshark capture). We tried to test out with simple PAC files as well and it is reproducable easliy.

    There seems to be some problem with IE and PAC file processing while accessing www.bbc.com  and pages internal to that site. The more intresting part is after this happens all the new tabs opened in the same window also doesn't work ,no matter whichever site you try to access over the internet.

    Would like to know is there any know issue or workaround to fix this type of issue.

    Thanks in advance

     

    Thursday, January 6, 2011 1:50 PM

Answers

  •  

    Hi,

     

    May I know the versions of Windows and Internet Explorer you are using? Do all the computers on this network meet this issue?

     

    Based on my research, I would like to suggest the following:

     

    1.    Ensure that the computer is using the correct DNS server for name resolutions and check the following:

     

    Please run the following command in a command prompt:

     

    >nslookup

    >www.microsoft.com (You can also try other URLs.)

     

    Please also check with the BBC website.

     

    Will the correct IP address be returned?

     

    2.    Please check if the website works without the proxy.

     

    3.    Check if it works in Safe Mode with networking.

     

    4.    Ensure this website is not blocked.

     

    5.    Double check the “.pac” file you created.

     

    6.    Try the method in the following Knowledge Base article:

     

    How to disable automatic proxy caching in Internet Explorer

    http://support.microsoft.com/kb/271361

     

    Hope this helps.

     

    Thanks.


    Nicholas Li - MSFT
    Please remember to click “Mark as Answer” on the post that helps you, and to click “Unmark as Answer” if a marked post does not actually answer your question. This can be beneficial to other community members reading the thread.
    Tuesday, January 11, 2011 8:27 AM
    Moderator

All replies

  •  

    Hi,

     

    May I know the versions of Windows and Internet Explorer you are using? Do all the computers on this network meet this issue?

     

    Based on my research, I would like to suggest the following:

     

    1.    Ensure that the computer is using the correct DNS server for name resolutions and check the following:

     

    Please run the following command in a command prompt:

     

    >nslookup

    >www.microsoft.com (You can also try other URLs.)

     

    Please also check with the BBC website.

     

    Will the correct IP address be returned?

     

    2.    Please check if the website works without the proxy.

     

    3.    Check if it works in Safe Mode with networking.

     

    4.    Ensure this website is not blocked.

     

    5.    Double check the “.pac” file you created.

     

    6.    Try the method in the following Knowledge Base article:

     

    How to disable automatic proxy caching in Internet Explorer

    http://support.microsoft.com/kb/271361

     

    Hope this helps.

     

    Thanks.


    Nicholas Li - MSFT
    Please remember to click “Mark as Answer” on the post that helps you, and to click “Unmark as Answer” if a marked post does not actually answer your question. This can be beneficial to other community members reading the thread.
    Tuesday, January 11, 2011 8:27 AM
    Moderator
  • I have experienced similar issues - specifically with the BBC, specifically through a corporate proxy solution.

    A couple of things to be aware of - firstly the BBC site is element heavy - MANY different 'bits' need to be loaded to paint the page.

    Secondly, the site does not all sit behind 'www.bbc.co.uk', many of the elements originate from an alternative bbc domain, specifically - static.bbci.co.uk

    Third, some of the elements are blocked by filtering solutions (such as SmartFilter) which may reside on your proxy.

    A key learning for me was the elements being blocked and re-directed by the filtering tools on the Proxy... these tools send a 're-direct' back to the browser, regrettably in our environment, that re-direct was to an internal IP adress - which you may expect - however;

    1 - due to the way the PAC file chooses to go 'direct' for internal IPs, as opposed to via the proxy for internet addresses, and the fact that IE caches (see the other posted comment regarding 'disable automatic proxy caching') the results of the PAC processing, and apparently gives priority to 'DIRECT' returns over 'proxied' returns.

    2 - the specific 'internal' adress, was actually on the outside of the proxy - not routable form our sub-net, so you have to go THOUGH the proxy to get to the error page - not good given the direct result from the PAC file, the practical up-shot, was

    - that a number of elements would load as expected from the site
    - a blocked element would be re-directed to the 'internal' site
    - the browser would cache the re-direct result
    - further elements would not be available from BBC

    My solution for this, was to put a specific exception in place for the re-directed IP, that caused the PAC file to route the request through the proxy.

    Note - I only found out what was happening, by closely monitoring the activities using 'HttpWatchBasic', and occasionally WireShark.

    Thursday, May 23, 2013 5:24 PM