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I would like to know, in Internet Explorer, the difference between "Automatically Detect Setting" and "Use Automatic Config Script".

I think I know that "Automatically Detect Setting" makes the browser locate and look for http://wpad/wpad.dat which will then direct it to look for the proxy server.

"Use Automatic Config Script" will just go straight to the location and run the proxy script.

To me, they are all related to locating the proxy script.

Is that correct?
What is the actual difference?

Thanks in advance and happy Thanksgiving Day for those in NA!

Blue Tongue
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1 Answers1

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To me, they are all related to locating the proxy script.

That's not wrong, but there is more to it

"Automatically Detect Settings" is a little more sophisticated than you assume, and checks a number of locations for wpad.dat:

  1. If using DHCP, send a DHCPInform request for option 252
  2. Try and resolve nbname WPAD using WINS and secondly NetBT (if these are enabled)
  3. Try and resolve wpad using DNS devolution with the connection-specific DNS suffix:
    • http://wpad.intern.my.domain.local/wpad.dat (<-- same as http://wpad/wpad.dat)
    • http://wpad.my.domain.local/wpad.dat
    • http://wpad.domain.local/wpad.dat

"Use Automatic Configuration Script" on the other hand allows Administrators to specify the url to an Internet Explorer configuration script (*.ins) that can include, but is not limited to a wpad url.

Mathias R. Jessen
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