What is Zscaler and How It Works?

Zscaler is a cloud-based security platform that provides secure access to applications and resources. As more organizations adopt cloud computing and support remote workforces, traditional network security approaches like on-premise firewalls often fall short. Zscaler offers a cloud-native solution tailored to protect users, devices, and data across globally distributed multi-cloud environments.

With data breaches and cyber threats on the rise, cloud security has become an indispensable capability for modern enterprises. Zscaler simplifies operations with an integrated platform delivering cloud firewall, web security, sandboxing, DNS filtering, DLP, and more. Its in-line proxy architecture provides high-performance inspection of web and application traffic over any port or protocol.

Let’s take a deeper look at what Zscaler is, how its architecture works, and key use cases in today’s IT landscapes.

Definition of Zscaler

Zscaler is a leader in the emerging category of Secure Access Service Edge (SASE). SASE converges networking and network security into a single, cloud-native platform. Zscaler’s globally distributed cloud platform examines traffic at scale to protect organizations against cyberattacks and data loss.

The Zscaler Zero Trust Exchange inspects all traffic headed to the internet or internal applications—whether from users, devices, or workloads across cloud, on-premises, and home networks. Its consolidated security stack eliminates disjointed legacy network and security point products.

Importance of Cloud Security in Modern IT Landscapes

Traditional security models operate on an implicit trust model inside the network perimeter. However, cloud adoption, remote work, and bring your own device (BYOD) policies have dissolved the network perimeter.

71% of internet traffic now originates from mobile devices. 93% of enterprises have a multi-cloud strategy. The pandemic triggered a 138% year-over-year increase in attackers targeting cloud services.

To protect distributed users, devices, and cloud workloads, organizations need a cloud-based security platform with unified policies. Zscaler provides this with the scale, availability, and performance of its global cloud to enable secure digital transformation initiatives.

Overview of Zscaler

Zscaler delivers Zero Trust network access and internet security from the cloud. Its unified platform reduces complexity and cost compared to traditional network security stacks.

What is Zscaler and How It Works? 1

Zscaler as a Cloud-Based Security Platform

The Zscaler Zero Trust Exchange is built on over 150 global data centers designed specifically for security processing. Instead of backhauling traffic over expensive MPLS circuits to regional hubs, Zscaler inspects traffic locally in data centers closest to the user.

By moving security to the cloud, Zscaler eliminates significant cost and networking complexity from acquiring, deploying and maintaining security appliances. Consolidating disjointed security services also reduces operational overhead for managing policy and reporting across numerous point tools.

Key Features and Capabilities

Zscaler internet access delivers cloud-based web gateway functionality combined with next-generation firewall services:

  • URL filtering blocks access to risky sites based on web content categories
  • Advanced threat protection detects zero-day malware and ransomware
  • Cloud sandbox detonates suspicious files in a disposable cloud environment
  • Cloud firewall sets identity-based access policies for applications and resources
  • Data loss prevention to discover/control unauthorized data in motion
  • Bandwidth control and traffic shaping policies optimize network utilization

Zscaler private access replaces VPNs with zero trust network access:

  • Application segmentation limits access to private apps/data per user role
  • Multi-factor authentication and device posture checks validate user identities
  • Micro-tunnel creation provides access only to authorized resources
  • Just-in-time, least privileged access improves security posture

By consolidating these capabilities into an integrated platform, Zscaler reduces cost, complexity, and security gaps.

Components of Zscaler

Zscaler’s cloud security platform consists of two main product suites: Zscaler Internet Access (ZIA) and Zscaler Private Access (ZPA).

Zscaler Internet Access (ZIA)

ZIA sits between users and the internet to secure web traffic across networks and devices. It protects users from threats, ensures compliance, and sets identity/context-based access policies.

Web Security

ZIA proxies inbound and outbound web traffic to apply:

  • URL filtering by content categories (e.g gambling, hate, pornography)
  • Protection against phishing attacks and botnets
  • Behavioral analysis to detect ransomware download activity

Cloud Firewall

The ZIA cloud firewall sets identity-aware policies limiting application access by users, groups, locations, and risk profiles. This reduces attack surfaces by only allowing authorized traffic based on contextual information.

Data Protection and Loss Prevention

ZIA discovers, monitors, and blocks the transfer of sensitive data to reduce the risk of data loss. It fingerprints structured data like credit cards, as well automated scanning of unstructured data using regex patterns, machine learning, and optical character recognition.

Zscaler Private Access (ZPA)

ZPA replaces VPNs with a zero trust network architecture to secure application access. It verifies user identities and device health before granting least-privileged access to private applications.

Zero Trust Network Access

True zero trust principles go beyond VPN tunnel access to individually authenticate users and validate device/traffic integrity before allowing connections. ZPA acts as an application-specific SSL proxy sitting closest to the resource being accessed. This eliminates exposure from broad network access.

Secure Remote Access

Organizations can enable secure remote user access to internal web apps quickly without costly network changes. ZPA routes only authenticated user traffic from authorized devices to specific web servers, reducing the internal attack surface.

By moving application security to the edge, ZPA provides fast and simple access while improving security over VPNs. Segmentation and least privilege access prevent lateral attacker movement across networks.

How Zscaler Works

This section examines Zscaler’s cloud-based architecture and key processes around traffic inspection, policy enforcement, and zero trust network access.

Zscaler’s Global Cloud Infrastructure

The Zscaler Zero Trust Exchange consists of over 150 data centers around the world operated by Zscaler. This global cloud infrastructure provides the foundation for scalable, high-performance security services.

Geographically Distributed Data Centers

With data centers across every major region, traffic is routed to the nearest Zscaler location at line speed. Forward proxies in data centers inspect traffic instead of routing it over the internet directly. This local redirection provides faster access while enabling consistent security scanning.

Multi-Tenant Architecture

Each Zscaler data center runs a proprietary multi-tenant software stack supporting all customers simultaneously. User identities, policies, and reporting are segmented per customer for privacy, while taking advantage of shared infrastructure. This delivers security-as-a-service at cloud scale and availability across the globe.

Traffic Redirection and Inspection

Zscaler forwards traffic destined for the public internet to the nearest data center for policy and security inspection.

Redirecting User Traffic to the Nearest Zscaler Data Center

Zscaler forwarding policies transparently redirect outbound user traffic to the nearest Zscaler data center over encrypted tunnels (IPsec or GRE). Appliances on the enterprise network called Zscaler Enforcement Nodes provide this seamless redirection.

Inspection of Web and Application Traffic in Real-Time

At the Zscaler data center, inbound and outbound traffic undergoes full TLS inspection powered by the platform’s proxy architecture. The multi-tenant software stack scans traffic per defined policies to filter unwanted content, detect threats like viruses and intrusions, and prevent data loss.

Security Policies and Controls

Zscaler provides centralized policy management to enforce security, access requirements, bandwidth policies and more.

Configuring Security Policies Based on User, Device, and Location

Admins create granular access policies based on user identity, group membership, device type, location, and other criteria. For example, restrict personal iOS device access to recreation websites only during non-work hours for a user segment.

Application of Security Controls Such as URL Filtering, Threat Protection, and Encryption

Policies determine the appropriate security controls applied to traffic including whitelist/blacklist website filters, antivirus scans, sandbox file analysis, intrusion prevention, TLS encryption triggers, and data loss prevention.

Zero Trust Network Access (ZTNA) Model

Zscaler Private Access implements a zero trust network approach to application access by verifying user identity and device health for every connection.

Authentication and Authorization

ZPA first authenticates user identities through SAML integration with directories like Active Directory or cloud providers. After verification, admins configure authorization policies determining which users/groups can access an application.

Least Privilege Access

Instead of full network access, ZPA establishes application-specific micro tunnels granting restricted access to resources per policy. Sessions provide minimum required privileges, enhancing security.

Integration with Cloud and On-Premise Applications

In addition to securing internet traffic, Zscaler platforms integrate with private applications across cloud or internal networks.

Forwarding routes directly to the cloud from Zscaler data centers provide faster access times to services like Microsoft 365 or Salesforce. Zscaler secures the traffic in-line before reaching the provider.

Extending Security to On-Premise Resources

ZPA delivers secure remote access to internal web apps or servers by placing an SSL proxy closest to the local resource. This applies policy checks before allowing traffic over micro tunnels to authorized on-prem destinations.

Benefits of Zscaler

Zscaler brings significant advantages as a cloud-native platform tailored for zero trust requirements of the modern enterprise:

Enhanced Security

By moving security to the cloud instead of appliances, Zscaler provides a scalable way to secure elastic cloud environments and distributed mobile users.

Protection Against Cyber Threats

Zscaler boards over 120 billion web transactions and blocks 100 million threats daily to derive actionable intelligence and prevent zero-day attacks. Cloud sandboxing, antivirus, botnet filtering, and IPS defend against malware.

Data Loss Prevention

Identify and control sensitive data like PII or financial data in web/internet traffic to reduce risk of theft or accidental disclosure that triggers compliance violations.

Improved Performance

Processing traffic locally while adding security scanning minimizes network latency and congestion which application speed over VPNs or MPLS.

Accelerated Access to Applications

Zscaler tenants redirect traffic to the nearest data center, significantly reducing round trip times. Real user tests found 30-40% faster Office 365 access compared to routing directly from branch offices.

Reduced Latency

By applying policy checks locally, Zscaler avoids multiple network hops adding latency which degrades performance. Average connection times dropped 60-80% with Zscaler according to customer analyses.

Simplified Management

Consolidating security services into Zscaler’s integrated platform reduces device sprawl and overhead of managing hundreds of disjointed appliances.

Centralized Policy Management

Admins enforce consistent policies for on-prem and cloud environments through a unified management console instead of using multiple interfaces.

Streamlined Administration and Reporting

IT spends less time maintaining infrastructure, while Zscaler portals provide enterprise-wide monitoring into web traffic, threats, bandwidth, users, applications, locations, and more.

Use Cases

Major drivers prompting enterprises to adopt Zscaler include:

Secure Web Access

Zscaler Internet Access replaces datacenter security stacks to protect campus, branch office, and mobile user access to cloud/internet destinations. Traffic redirection policies send web flows via ZIA for policy and threat inspection.

Remote Access and Telecommuting

Supporting large remote workforces securely accelerated Zscaler adoption during the pandemic. ZIA secures web access from home devices. ZPA replaces VPNs for simpler access to internal resources.

Cloud Application Security

Forwarding cloud-destined traffic from locations to nearby ZIA data centers increases Office 365, Salesforce, Workday and other SaaS performance while improving security.

Secure Access to Private Applications

ZPA’s zero trust network access model balances security and convenience for external partners accessing supply chain apps or for remote employees connecting to internal web servers.


As enterprise infrastructure spreads across cloud and edges, network security requires transformation. Zscaler represents a cloud-native platform tailored to secure access in highly distributed environments based on zero trust principles.

By providing security-as-a-service from 150+ global data centers, Zscaler improves protection while accelerating performance, reducing latency, and streamlining operations. Consolidating disjointed appliances and point security products into an integrated solution simplifies management overhead.

As more organizations strategize around multi-cloud adoption, enterprise mobility initiatives, and supporting remote workers at scale, purpose-built cloud security platforms like Zscaler will underpin secure digital transformation. We can expect continued innovation from Zscaler expanding its unified SASE platform to fulfill modern zero trust use cases.

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