https://help.zscaler.com/z-app/best-practices-using-pac-files-zscaler-app
Zscaler Client Connector (formerly Zscaler App or Z App) uses PAC files in the Forwarding Profile and in the App Profile. The Forwarding Profile PAC file is used to direct system, browser, and application traffic to Zscaler Client Connector. When Zscaler Client Connector receives traffic, the App Profile is used to direct that traffic to the Zscaler cloud. Zscaler Client Connector directs traffic to the closest data center according to the App Profile PAC file, by changing the proxy return statement to the IP address of the geographically closest data center.