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The 13 Most Common Technical Interview Questions and How to Answer Them

Looki​ng for a job? Get ready for the​ technical interview! Es​pecially for softw​are engineers, this means man​y questions about what the​y know and ho​w they solve problems. While eac​h company might ask differ​ent questions, som​e are asked by many ​places.

What is a technical interview?

A technical interview is a type of job interview that focuses on assessing a candidate’s skills, knowledge, and proficiency in areas specific to the technical aspects of a job. While traditional job interviews might explore broad subjects such as background, experience, team fit, and problem-solving abilities, technical interviews delve deep into the nitty-gritty of a candidate’s technical expertise.

Most common technical interview questions
Most common technical interview questions

For professions like software engineering, data science, and IT roles, a technical interview can include:

  • Coding Challenges: Candidates may be asked to write or analyze pieces of code. Platforms like LeetCode, HackerRank, and Codility are often used for this purpose.
  • Algorithm and Data Structure Questions: These assess understanding and application of algorithms and data structures, including searching, sorting, tree and graph traversal, and more.
  • System Design: For more senior roles, candidates may be asked to design a system or architecture, highlighting how different components interact.
  • Technical Problem Solving: This could involve addressing real-world problems that a company has faced or might face.
  • Technical Knowledge: Questions related to specific languages, technologies, tools, or methodologies pertinent to the role.
  • Whiteboard Challenges: Candidates might be asked to explain or design concepts on a whiteboard, demonstrating their thought process.
  • Hands-on Tasks: For roles like network engineers or database administrators, tasks might include setting up a network or designing a database schema.

Technical interviews are not limited to the tech industry; they can be found in any sector where specific technical skills and knowledge are required, from finance to biotech. Their main goal is to ensure the candidate possesses the technical chops to succeed in the role they’re applying for.

Whether you’re a budding software engineer or a seasoned IT professional, mastering these basic technical interview questions can be your ticket to landing your dream job.

1. Explain the difference between a stack and a queue.

Answer: A stack operates based on the Last-In-First-Out (LIFO) principle where the last item you insert is the first one to come out. Think of it like a stack of plates: you add (push) a plate to the top and remove (pop) the top plate. A queue, on the other hand, operates on the First-In-First-Out (FIFO) principle, like people waiting in line. The first one to get in line is the first one to be served.

2. What’s the difference between an inner join and a left join in SQL?

Answer: In SQL, an inner join returns rows where there’s at least one match in both tables, whereas a left join returns all rows from the left table, and the matched rows from the right table. If there’s no match, the result will contain NULL.

3. Can you explain polymorphism in Object-Oriented Programming (OOP)?

Answer: Polymorphism, derived from Greek meaning “many shapes”, allows objects to be treated as instances of their parent class rather than their actual type. For example, if we have a parent class called “Animal” and child classes like “Dog” and “Cat”, polymorphism lets us treat both Dog and Cat objects as if they were Animal objects.

4. Describe what recursion is in programming.

Answer: Recursion occurs when a function calls itself in order to solve a smaller instance of its problem. An example is the factorial function, where the factorial of n (n!) is n times the factorial of (n-1).

5. How would you find the duplicate number in an array containing n+1 integers between 1 and n?

Answer: One way to solve this is by using the Floyd’s Tortoise and the Hare (Cycle Detection) algorithm. By treating the array as a linked list, you can detect the cycle, which will lead you to the duplicate number.

6. What is the difference between “==” and “===” in JavaScript?

Answer: The “==” operator checks for loose equality and performs type coercion, meaning it converts the operands to the same type before making the comparison. The “===” operator checks for strict equality, meaning both the value and the type must be identical.

7. Can you describe the Model-View-Controller (MVC) pattern?

Answer: The MVC pattern is a design pattern used in software engineering aimed at separating an application into three interconnected components:

  • Model: Represents data and the business logic.
  • View: Represents the user interface elements and presentation.
  • Controller: Acts as an interface between the Model and View, receiving user input and deciding what to do with it.
Basic technical interview questions
Basic technical interview questions

8. What are the advantages of using Git?

Answer: Git, a version control system, offers several benefits:

  • Distributed Version Control: Allows multiple developers to work simultaneously.
  • Branching and Merging: Feature development can be isolated, and then easily merged.
  • History Tracking: Every commit acts as a snapshot of the project history.
  • Collaboration: Multiple collaborators can work on a project without interfering with each other’s changes.

9. Can you explain the difference between “system testing” and “integration testing”?

Answer: Integration testing focuses on the interfaces between units of software, ensuring that they interact correctly. System testing, on the other hand, evaluates the system’s overall behavior and ensures the entire system functions correctly.

10. How would you deal with a situation where a project you’re working on has a tight deadline, but you’re encountering numerous bugs?

Answer: Prioritize and triage bugs. Address critical bugs that affect the project’s main functionality first. Communicate openly with the team and stakeholders about potential delays. Consider implementing a continuous feedback loop with QA teams to quickly identify and resolve issues.

11. Describe a situation where you had to make a tough decision in your previous role.

Answer: In my previous role, we had two projects running concurrently. One project was running smoothly, while the other faced challenges. I had to decide to reallocate resources from the smooth project to address the challenges in the other, risking the timeline of both. I communicated my decision and its rationale to stakeholders and ensured everyone was aligned.

12. How do you ensure the security of your code?

Answer: Security can be ensured by:

  • Keeping software and libraries updated.
  • Validating and sanitizing user input to prevent SQL injections or XSS attacks.
  • Using prepared statements in databases.
  • Regularly reviewing and auditing code.
  • Staying updated on the latest security threats and best practices.

13. Can you explain the concept of “Big O” notation?

Answer: Big O notation describes the performance or complexity of an algorithm. It gives an upper bound on the time taken by an algorithm in terms of the size of the input. For example, an algorithm with a complexity of O(n) would take linear time to execute, increasing linearly with the size of the input.

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In Short, these questions are common in technical screen interviews for software engineers. Besides technical skills, it’s important to show good communication, problem-solving abilities, and fit with the company’s values. Good luck in your interviews!

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