What is the primary function of ZIA Public Service Edges in the Cloud Firewall architecture?

Within the ZIA Cloud Firewall and broader Zscaler Internet Access architecture, Public Service Edges (PSEs) are the core policy enforcement points. User traffic is steered (via tunnels, PAC files, or agents) to the nearest PSE, where Zscaler performs security inspection and policy evaluation. At this point, the Cloud Firewall, URL filtering, SSL inspection, IPS, sandboxing, and other security engines are applied according to the user’s identity, group, location, and defined policies.

Although the PSEs naturally participate in traffic distribution across the global Zscaler cloud, their primary purpose is not generic load balancing or network transit; rather, they host the full security stack and make real-time allow/deny/log decisions. They also enforce bandwidth controls, application rules, and advanced threat protections before forwarding allowed traffic to the internet.

They are not responsible for managing endpoint security updates or providing general cloud storage. Instead, they serve as inline security gateways that enforce Zero Trust access and granular firewall rules at scale. Therefore, the correct description of their role in the Cloud Firewall architecture is that they act as key policy enforcement engines.

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