Born in the cloud to secure the cloud

Built from the ground up, Zscaler's multi-tenant cloud architecture lets customers enjoy elastic scale while maintaining security and data privacy.

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The founder’s vision

Zscaler was started in 2008 when a number of industry veterans, including CEO Jay Chaudhry, came together to create the next step in network security. Zscaler was built on several foundational observations, including the fact that business and personal applications had begun moving to the cloud, Web 2.0 was leading to the evolution of web-based apps, and that the adoption of mobility meant that users could be working from anywhere. These observations generated several tenants of a next generation security architecture, including:

  • Perimeter-based security appliances can’t provide real protection, because both users and the apps that they are seeking no longer reside within any perimeter.
  • Point products, even those considered best-of-breed, are not designed to interact with one another for a holistic perspective—IT sees only pixels, not the picture.
  • The majority of unresolved threats come from the Internet, so the most effective place to handle security is in the cloud between the users and the web.
  • Threats evolve constantly, and to catch zero-day exploits before they hit the network, it is impossible to rely on signatures alone.

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Zscaler's vision of transforming security with our cloud-delivered security offering.

Architecture—five key game changing technologies


  • Ultrafast (body) scanning
  • Detect malicious content, data leakage, classify URLs

Page Risk Index

  • Dynamically computed
  • Better fraud prevention


  • 50:1 Log reduction
  • Real-time consolidation
  • Trans-level drill-down

10 Gbps Platform—Latency in Micro-secs

64-bit Architecture, Next Gen TCP stack, Drivers; SSMA
(Single Scan Multi Action)

Distributed Network, Multi-tenant Architecture

The answer was a cloud-based firewall proxy architecture, designed to examine web traffic over all ports and protocols including the growing segment that was SSL encrypted. Policies must follow the user, regardless of their location or device. Security functionality must interoperate, combining findings from different approaches to deliver a holistic perspective. The platform must be capable of recognizing threats independent of signature feeds, and should be able to propagate threat information across the cloud in real-time. Visibility must be available on demand, and go from an at-a-glance view to the user/device level in a few clicks.

Realizing this vision included design of almost fifty new, patented technologies, including:

  • Distributed, multi-tenant architecture, built from the ground up for elastic scale while maintaining security and data privacy.
  • 10 Gbps platform, based on a next-gen TCP stack and drivers as well as revolutionary Single Scan Multiple Action technology that enables inspection of every byte of traffic by every service.
  • ByteScan, which provides ultrafast content scanning as well as detection of malicious sites, content, and data loss, removing dependency on signatures.
  • Page Risk Index, which delivers dynamically computed information based on real-time web activities instead of relying on reputation alone.
  • Nanolog, which encrypts and compresses web logs in a 50:1 ratio to enable complete visibility and drill-down in seconds.
Zscaler's multi-tenant cloud security architecture — a pure cloud solution.

How Zscaler works

Zscaler’s architecture was created from scratch as a pure cloud provider. We deliver a truly multi-tenant and highly scalable platform by functionally distributing components of a standard proxy to create a giant global network that acts as a single virtual proxy. Any user can go to any gateway at any time for policy-based secure Internet access. Zscaler infrastructure comprises three key components: Zscaler Enforcement Nodes (ZENs), Central Authority (CA), and Nanolog Servers.

Learn more about:
Central Authority >
ZENs >
Nanolog clusters >





Central Authority (CA)

The Central Authority complex is the brain of the Zscaler cloud. The CA manages and monitors all nodes and ensures that they are always up-to-date with the latest real-time feeds and software, and that they are synchronized to propagate threat intelligence cloud-wide. The CA directs users to the closest Zscaler Enforcement Node, ensuring that policy follows the user with minimum latency. The Central Authorities are a globally distributed peer-to-peer cluster with an automatically elected master. This ensures all cloud components can always talk to a CA even if there are major Internet outages that isolate an entire region.

Through its multi-tenant architecture, the CA provides each organization with its own secure portal to administer policy. Any change to the policy is communicated to the ZENs within seconds. The CA provides an end-user authentication framework through integration with Secure LDAP or ID Federation systems.

Zscaler's central authority complex is the brain of our cloud security architecture.
Zscaler Enforcement Node (ZEN) tackles security, management, and compliance policies

Zscaler Enforcement Node (ZEN)

An enterprise forwards all web traffic to the nearest ZEN, where security, management, and compliance policies served by the CA are enforced.

Powered by over thirty patents, each ZEN is a fully featured inline proxy that enforces policies with user-level granularity. The ZEN incorporates a hardened custom-built OS and a custom TCP/IP stack to deliver 90% of transactions in less than 90 microseconds. Zscaler’s ByteScan technology enables each ZEN to scan every byte of the web request, content, responses, and all related data for inline blocking of threats like viruses, cross site scripting (XSS), and botnets. This capability also enables Dynamic Content Classification (DCC) of unknown sites. By scanning each page, the ZEN computes a PageRisk index for every page loaded and enables administrators to control content served to their users based on acceptable risk.

The ZEN also incorporates Zscaler’s unique authentication and policy distribution mechanism that enables any user to connect to any ZEN at any time. This enables enterprises to simply point traffic to any ZEN and ensure full policy enforcement, while getting all reports back in realtime.

Nanolog servers

Backed with multiple patents, Zscaler’s Nanolog technology on every ZEN performs lossless compression of logs by a factor of 50:1, enabling administrators to access any transaction log almost instantly. Logs are transmitted every second to the Nanolog servers over secure connections, and multicast to multiple servers for redundancy. Through an innovative reporting and database framework created specifically for web logs, the Nanolog server can support 15 million logs per second.

This technology provides an administrator with real-time reports and the capability to query complete transaction-level details for any user, department or location at any time in seconds. Each server has over 16 Terabytes of capacity, enabling Zscaler to provide multiyear data retention.

Zscaler nanolog server technology provides real-time reports and transaction-level user detail.

Security and data privacy

Data privacy and security are fundamental to any multitenant architecture. Zscaler ensures these principles in the following ways:

Privacy protection at web transaction level:

  • Zscaler Services never store any transaction content
  • Transaction content is never written to disk, all inspection takes place in memory
  • Logs are stored and transferred in an encrypted format
  • Logs are only viewable via the Zscaler UI with Admin privileges

Protection at the facilities level:

  • Security standards on par with world-class financial and data centers for hub facilities (Either ISO27001 or SSAE 16 certified)
  • Authorized personnel must pass through multiple levels of security and scanning to gain access
  • All data centers are completely anonymous

Protection at the network level:

  • Logs are never stored in clear text
  • Logs are transmitted as indexed, compressed, differential logs
  • All logs are transferred encrypted using SSL
  • Gateway nodes can be accessed only from the central authority

Zscaler is ISO27001-certified and provides 99.999% availability SLA—with additional SLAs on latency and virus capture too. This level of performance is prohibitively expensive to try to offer yourself with security appliances.

Learn more about the world's largest security cloud

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