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Palo Alto Networks interview notes, page 1 of 4

Large Enterprises

Most of these Palo Alto Networks write-ups come from Software Engineers (28), then Product Managers (2) and Backend Engineers (1). The most reported rounds are the technical phone screen (10), the system design round (8), the onsite coding round (4) and the product sense round (4).

31 interview notes · updated Sep 2026

Palo Alto Networks·Software Engineer·Onsite - System Design / Architecture

Apr 2026
Did a system design round for a software engineering role at Palo Alto Networks. The prompt was to design a metrics monitoring system, which sounds scoped until you actually start pulling on the threads.
  • Design a metrics monitoring system.

“Spent the first few minutes just trying to nail down what kind of metrics we're talking about.”

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Palo Alto Networks·Software Engineer·Onsite - System Design / Architecture

Apr 2026
System design round at Palo for a software engineer role. The whole session was basically one big rate limiter question broken into layers, starting simple and getting progressively harder until we were talking distributed consensus and failure modes.
  • Design a rate limiter for a backend service that enforces per-identity limits (per user ID, IP, or API key), handles high concurrency, scales to millions of requests per second, and works across a distributed deployment. Walk through algorithm choice, data structures, rejection behavior, and how you'd handle distributed state.

“This was the whole interview basically.”

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Palo Alto Networks·Backend Engineer·Onsite - System Design / Architecture

Apr 2026
Principal-level backend interview at Palo Alto Networks focused almost entirely on rate limiting, going from a basic design all the way through concurrency and distributed systems. The depth they expected was no joke.
  • Design a rate limiter for an API gateway that supports per-key limits (per-user, per-IP, etc.) with a configurable number of requests per time window. Walk through the common approaches and pick one.
  • How do you make your rate limiter thread-safe when multiple concurrent requests come in for the same key at the same time?
  • Now scale this to very high QPS. How do you shard the limiter state, handle distributed coordination, and reason about correctness versus performance at that scale?

“I went with sliding window counter because it smooths out burst traffic better than fixed window without the memory cost of a full log.”

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Palo Alto Networks·Software Engineer·Onsite - Product Sense / Strategy

May 2026
Got a product marketing case question at Palo Alto Networks, just the one question as far as I could tell. Short and a bit ambiguous, which made it harder than it looks.
  • How would you market a high-quality pure drinking water bottle?

“My first instinct was to go broad and just list channels, which was probably the wrong move.”

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Palo Alto Networks·Software Engineer·Technical Phone Screen

May 2026
Interviewed for a software engineer role at Palo Alto Networks and hit a LeetCode-style coding problem. Pretty standard stuff, nothing too wild.
  • Solve the classic sorted array merge problem: given two sorted integer arrays, merge the second into the first in-place.

“LeetCode 88.”

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Palo Alto Networks·Software Engineer·Onsite - Coding / Algorithms

May 2026
Palo Alto Networks coding round for a Software Engineer role. One meaty design-and-implement question that took up the whole session, walking through data structures, a whiteboard sketch, a dry run, and complexity analysis.
  • Design and implement an in-memory LRU cache with a fixed capacity. It should support get(key) and put(key, value), both in average O(1) time. Walk through your data structures, sketch it out, do a dry run on a specific sequence of operations, and explain how you'd handle edge cases like capacity zero, duplicate keys, and hot keys.

“I knew it was an LRU cache the second they finished the sentence, which was both reassuring and a trap because I rushed into code before properly explaining the structure.”

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Palo Alto Networks·Software Engineer·Onsite - Coding / Algorithms

May 2026
Did a virtual onsite coding round for a senior security researcher role at Palo Alto Networks. The whole thing got a bit chaotic because I couldn't write Python from memory and the HackerRank platform wouldn't let me switch to C++, so we ended up pivoting to a discussion-based format. Interviewer was flexible about it, which saved the session.
  • Given two programs that appear to work correctly, how would you verify that they won't cause issues in a real running system? Walk through your analysis approach and identify edge cases.

“This is where things went sideways for me.”

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Palo Alto Networks·Software Engineer·Onsite - Product Sense / Strategy

May 2026
Interviewed at Palo Alto Networks for a product marketing role and got hit with a go-to-market case question about a career coaching app. Not the most technical interview but it made me think harder than expected.
  • How would you develop and execute a marketing strategy for a career coaching mobile app?

“I started with target audience segmentation which felt right, but I think I spent too long on that and rushed the channel strategy.”

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Palo Alto Networks·Software Engineer·Technical Phone Screen

May 2026
Interviewed for a software engineering role at Palo and got a meaty systems/concurrency problem about building an alert execution engine from scratch. The problem had a lot of moving parts and I think I handled most of it but the state transition piece tripped me up a bit.
  • You're given a client API with methods for fetching alert configs, executing metric queries, and sending notifications. Build an alert execution engine that evaluates each alert on its own interval, fires notifications when a metric crosses a threshold, and resolves alerts when they drop back below it.

“This one looked manageable at first glance but the complexity stacks up fast.”

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Palo Alto Networks·Software Engineer·Technical Phone Screen

May 2026
Initial screen for a Security Researcher role at Palo Alto Networks, conducted by a Principal Researcher. Similar format to another round I'd done recently but pushed harder on depth, and closed with a trace analysis question I wasn't fully expecting.
  • Walk through a packet or execution trace and identify what's happening or what's anomalous.

“This is the one that tripped me up a bit.”

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