Qualys Software Engineer Interview Experience

I recently interviewed at Qualys for a Software Engineer role with 2.5 years of work experience. The process consisted of four rounds: one screening round, two technical interviews, and a managerial round.

Here is a breakdown of the questions and topics covered during the interviews.

Round 1: Screening Round

This round focused on my background, experience, and career goals.

• Tell me about yourself and your technical background.

• Walk me through the projects you have worked on.

• Which programming languages and technologies are you most comfortable with?

• What motivated you to explore new opportunities?

• What is your current CTC?

• What are your compensation expectations?

Round 2: Technical Interview 1

This round covered DSA, C++ fundamentals, AI projects, and cloud technologies.

DSA and Problem-Solving

• Find the Starting Point of a Cycle in a Linked List: Given a linked list containing a cycle, return the node where the cycle begins. Explain the approach and its time and space complexity.

• Valid Parentheses: Determine whether a string containing different types of brackets is balanced.

• Move Zeroes: Move all zeroes in an array to the end while maintaining the relative order of non-zero elements. Discuss the optimal in-place solution and its complexity.

C++ Concepts

• What is the difference between an abstract class and an interface-like design in C++?

• Explain function overloading and function overriding with examples.

• How do virtual functions support runtime polymorphism?

AI and Cloud Technologies

• Explain the architecture of an AI-based project you have worked on and the challenges you faced during implementation.

• What is the HNSW algorithm, and how is it used for approximate nearest-neighbor search?

• What is Google Cloud SQL, and how does it differ from managing a database on a virtual machine?

Round 3: Technical Interview 2

This round focused on backend development, Java, SQL, DSA, and AI system architecture.

Backend and Core Concepts

• What are REST APIs, and how would you implement a POST endpoint to create a new resource?

• Explain Java multithreading, thread synchronization, and the use of the synchronized keyword.

• What is the difference between HTTP status codes 401, 403, 404, and 500?

• What are primary keys, foreign keys, and unique constraints in SQL?

SQL and DSA

• Write an SQL query to find the second-highest salary in an employee table.

• Given a doubly linked list, reverse the list and explain the time and auxiliary space complexity.

• Insert a node at a specified position in a doubly linked list. How would you handle invalid positions?

• Explain binary search and identify the conditions required for its correct application.

AI and Multi-Agent Systems

• How does a multi-agent system differ from a single-agent system?

• What is the role of a supervisor agent in a multi-agent architecture?

• How can agents delegate tasks, share results, and handle failures during execution?

Round 4: Managerial Interview

The final round focused on project ownership, technical decision-making, communication, and troubleshooting.

• Walk me through a project you are particularly proud of.

• Explain the architecture of one of your AI projects and justify the technologies you selected.

• What was the most challenging technical problem you encountered, and how did you resolve it?

• How do you handle technical disagreements within a team?

• Why are you considering a change in your current role?

• Explain how DNS resolves a domain name to an IP address.

• What is the difference between TCP and UDP, and when would you use each?

• Suppose your laptop has become unusually slow. How would you investigate and troubleshoot the issue?

Overall Experience

The interview process covered DSA, C++, Java, SQL, REST APIs, cloud databases, AI concepts, multi-agent systems, and networking fundamentals.

Preparation tips:

• Practise linked lists, arrays, binary search, and common data structures, and be ready to explain time and space complexity.

• Revise the fundamentals of C++, Java, SQL, networking, and backend development.

• Understand the architecture, implementation details, and limitations of every project mentioned on your resume.

• For AI-related projects, prepare to explain the algorithms, design decisions, and how different components interact.

Hope this helps others preparing for Software Engineer interviews at Qualys. All the best!