When working on a big corporation it might be needed to know which proxy is being used on each site. This information is usually hidden in a Proxy auto-config file. This happens when in Internet Explorer the “Use automatic configuration script” is checked or in Firefox when “Use system proxy settings” is turned on.
Below you find a quick step-by-step guide to find out which file is being used and its contents
- Open Internet Explorer
- Click on the Tools menu (Alt+T) and select “Internet Options”
- Select the Tab Connections and click on “LAN Settings…”
Copy the text in the “Address” box below “Use Automatic configuration script” checkbox
- Open a new Browser Tab, paste the address and press Enter
- A new file .pac will be downloaded. Open it with your preferred text editor.
The downloaded .pac file is very easy to read. Nevertheless if you find it too confusing you can get more information from the Wikipedia article: Proxy auto-config.