PAC files are scripts that tell web browsers how to use proxies on the network. They use if-else statements to determine whether to use a proxy or a direct connection for traffic between the PC and the host, based on criteria such as the destination URL, the source IP address, or the network subnet12. The WSA can host PAC files on port 9001 by default, and this port can be changed in the PAC file hosting settings2. If the WSA host port is changed, the default port does not redirect web traffic to the correct port automatically; the browser needs to point to the new port in the PAC file URL2. The WSA does not host PAC files on port 6001 by default2. PAC files do not direct traffic through a proxy when the PC and the host are on the same subnet by default; this behavior depends on the PAC file logic12. References:

PAC file format

PAC file hosting on WSA