Zscaler - interview guide

Zscaler interview questions - a complete guide

Zscaler is a cloud security company - networking and security questions here matter as much as DSA. A group discussion is also reported in campus drives.

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About Zscaler

Zscaler provides 'Zero Trust' cloud security - a company's employees' internet and app traffic passes through Zscaler's cloud, where it is checked. It has large centres in Mohali and Bengaluru.

This guide covers 12 Zscaler interview questions with answers - what each question checks and how to answer it - plus the Zscaler interview process, round by round, a 7-day preparation plan for freshers, tips and the mistakes to avoid.

Zscaler hiring process

  1. Online test

    Reported: aptitude, coding and communication - or 4 DSA problems in some drives.

  2. Group discussion

    Reported in some campus drives.

  3. Technical interviews (2)

    Networking, OS and DSA.

  4. HR

    Fit and location.

Zscaler does not publish its India fresher interview process in detail (as of our check). This is based on candidate reports - many of them for experienced roles, so the fresher process can differ. Confirm with the recruiter.

Sources (checked 16 October 2026): Zscaler Careers. Hiring processes change - read the official notice before you apply.

Zscaler interview questions and answers

Security and networking

  1. 1.What does Zero Trust mean?

    What they're checking
    Zscaler's core idea.
    How to answer
    Nobody is trusted automatically - even inside the office network. Every request is checked for user, device and context, and access is given only to the app needed.

  2. 2.What is the difference between a VPN and Zero Trust access?

    What they're checking
    Understanding the product.
    How to answer
    A VPN brings the user inside the whole network - one hacked account opens up a lot. Zero Trust connects only to that one app, hiding the network.

  3. 3.What is the difference between a forward proxy and a reverse proxy?

    What they're checking
    Networking basics.
    How to answer
    A forward proxy goes out to the internet on behalf of users (like a company web filter). A reverse proxy sits in front of servers and distributes requests to them (like a load balancer).

  4. 4.What is the difference between a firewall, an IDS and an IPS?

    What they're checking
    Security basics.
    How to answer
    A firewall allows/blocks traffic by rules. An IDS spots suspicious traffic and raises an alert. An IPS spots it and blocks it too.

  5. 5.How does a SYN flood attack work, and how is it stopped?

    What they're checking
    TCP + security.
    How to answer
    The attacker sends many SYNs but never completes the handshake - the server's list of half-open connections fills up. Defences: SYN cookies, rate limiting and filtering upstream.

  6. 6.How does a domain name turn into an IP - step by step?

    What they're checking
    Depth in DNS.
    How to answer
    The browser/OS cache, then the resolver; the resolver goes from a root server to the .com server, then gets the IP from the domain's authoritative server and caches it for the TTL.

  7. 7.A user logs in from Delhi and London within 10 minutes - how would you detect it?

    What they're checking
    Security thinking.
    How to answer
    Keep each login's location and time; divide the distance between two logins by the time - if the speed is faster than an aeroplane, raise an 'impossible travel' alert.

Coding and OS

  1. 8.How do you quickly check a domain against a list of millions of blocked domains?

    What they're checking
    Choosing a data structure.
    How to answer
    A hash set for exact matches, O(1). If memory must be small and some false positives are fine, a Bloom filter first, then confirm.

  2. 9.How would you match domains against wildcard rules such as '*.example.com'?

    What they're checking
    A smart use of a trie.
    How to answer
    Split the domain by dots, reverse it (com, example, mail) and put it in a trie. While matching, if you hit a '*' node, that rule applies.

  3. 10.When does a page fault happen, and what does the OS do?

    What they're checking
    OS basics.
    How to answer
    A program asks for a page that isn't in RAM. The OS brings the page from disk (evicting an old page if needed), updates the page table and re-runs the instruction.

GD and HR

  1. 11.How would you open the GD topic 'Data privacy vs convenience'?

    What they're checking
    A GD has been reported in campus drives.
    How to answer
    Define the topic in one line, give one point for each side (the convenience of UPI, the risk of data leaks), and a balanced view. Let others speak too.

  2. 12.Why Zscaler?

    What they're checking
    Motivation.
    How to answer
    Your interest in cyber security - a course, a CTF or a project - and the growing role of cloud security.

7-day preparation plan for the Zscaler interview

  1. Day 1: Networking - TCP, DNS, HTTP/HTTPS.
  2. Day 2: Security - firewalls, proxies, attacks, Zero Trust.
  3. Day 3: OS - memory, paging, processes.
  4. Day 4: DSA - tries, hashing, strings.
  5. Day 5: Aptitude + timed coding.
  6. Day 6: GD practice - three topics.
  7. Day 7: A mock interview.

Preparation tips

  • Nail networking (TCP, DNS, HTTP, proxies) and security basics.
  • Explain the idea of Zero Trust in your own words.
  • Keep two points ready on current tech topics for the GD.
  • Tries, hashing and strings in DSA.

Mistakes to avoid

  • Not knowing networking basics at a security company.
  • In a GD, either staying silent or cutting others off.
  • Treating a proxy and a reverse proxy as the same thing.

Frequently asked questions

What is in the Zscaler online test?

According to reports, aptitude, coding and communication; 4 DSA problems in some drives.

Is there a group discussion at Zscaler?

A GD has been reported in some campus drives.

Where is Zscaler's India office?

Large centres are reported in Mohali and Bengaluru.

How much security does the Zscaler interview ask?

Networking and security basics come up commonly - Zero Trust, proxies, firewalls, TCP/DNS.

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