One or more proxy auto-configuration (PAC) files can be made available on an appliance for web browsers on clients. The browsers can use them to find proxies for accessing particular web pages.
A proxy auto-configuration file usually has .pac as its file name extension. There can be several of them on an appliance, for example, a proxy.pac and a webgateway.pac.
Under the WPAD (Web Proxy Auto-Discovery) protocol, a proxy auto-configuration file must have wpad.dat as its file name. Therefore, it can exist on an appliance only once.