100 CSE Fundamental Interview Questions and Answers.

A collection of the top 100 technical interview questions for CSE Students

1. Technical Questions (Based on Fundamentals)

Programming Concepts & Data Structures

1. What is the difference between C and Java?
   • C is a procedural programming language, whereas Java is object-oriented. Java supports automatic memory management (Garbage Collection), while C requires manual memory allocation.
2. What are the four pillars of Object-Oriented Programming (OOP)?
   • The four pillars are Encapsulation, Abstraction, Inheritance, and Polymorphism. They help in structuring programs effectively.
3. What is the difference between an interface and an abstract class in Java?
   • An abstract class can have both implemented and unimplemented methods, whereas an interface contains only abstract methods (before Java 8). A class can implement multiple interfaces but extend only one abstract class.
4. What is the difference between pass by value and pass by reference?
   • In pass by value, a copy of the variable is passed, and changes do not affect the original. In pass by reference, the memory address is passed, so changes reflect in the original variable.
5. What is the difference between stack and queue?
   • A stack follows LIFO (Last In, First Out), while a queue follows FIFO (First In, First Out).
6. What is the difference between an array and a linked list?
   • An array has a fixed size and contiguous memory allocation, whereas a linked list dynamically grows and stores elements at different memory locations.
7. What is recursion? Provide an example.
   • Recursion is when a function calls itself to solve a problem. Example: Finding the factorial of a number using recursion.
8. What is a binary search tree (BST)?
   • A BST is a tree where each node has at most two children, and left child values are smaller while right child values are greater than the parent node.
9. What is a hash table?
   • A hash table is a data structure that stores key-value pairs and uses a hash function for quick lookups.
10. What are the time complexities of searching algorithms?

• Linear Search: O(n)
• Binary Search: O(log n)

Database Management Systems (DBMS)

11. What is a database?

• A database is an organised collection of data that allows efficient storage, retrieval, and management. Related: RDBMS

12. What is the difference between SQL and NoSQL?

• SQL databases are relational and structured, whereas NoSQL databases are non-relational and flexible for unstructured data.

13. What is normalization in SQL?

• Normalization eliminates redundancy by dividing large tables into smaller, related tables.

14. What are the different types of joins in SQL?

• INNER JOIN, LEFT JOIN, RIGHT JOIN, FULL JOIN. They define how two tables are combined based on a related column.

15. What is the difference between DELETE and TRUNCATE in SQL?

• DELETE removes specific records and can be rolled back. TRUNCATE removes all rows but cannot be undone.

16. What is ACID in database transactions?

• ACID stands for Atomicity, Consistency, Isolation, and Durability, ensuring reliable transactions.

17. How do you find duplicate records in a table?

• Using GROUP BY with HAVING COUNT(*) > 1.

18. What is an index in SQL?

• An index speeds up data retrieval but consumes extra storage.

19. What is a primary key and a foreign key?

• A primary key uniquely identifies a record. A foreign key links tables and references a primary key in another table.

20. What is a stored procedure?

• A stored procedure is a set of SQL queries stored in the database to perform specific operations efficiently.

Operating Systems (OS)

21. What is an operating system?

• An OS manages hardware and software, enabling user interaction.

22. What is the difference between a process and a thread?

• A process is an independent execution unit, whereas a thread is a lightweight subpart of a process.

23. What is deadlock in an operating system?

• A deadlock occurs when two or more processes wait for each other indefinitely, preventing execution.

24. What are the different types of scheduling algorithms?

• FCFS, Round Robin, Shortest Job First, and Priority Scheduling.

25. What is virtual memory?

• Virtual memory is an extension of physical memory using disk space when RAM is full.

26. What is paging in an OS?

• Paging divides memory into fixed-sized blocks to optimise storage and reduce fragmentation.

27. What is a kernel in an OS?

• The kernel is the core of an OS that manages system resources and communication between hardware and software.

28. What is the difference between multiprocessing and multithreading?

• Multiprocessing runs multiple processes using multiple CPUs, while multithreading runs multiple threads within a single process.

29. What is context switching?

• Context switching occurs when the CPU switches between processes or threads, saving and restoring execution states.

30. What is the difference between 32-bit and 64-bit operating systems?

• A 64-bit OS can handle more memory and perform better on modern processors than a 32-bit OS.

Networking & Security

31. What is the difference between HTTP and HTTPS?

• HTTPS is a secure version of HTTP that encrypts data using SSL/TLS.

32. What is a firewall?

• A firewall is a security system that monitors and controls incoming and outgoing network traffic.

33. What is an IP address?

• An IP address is a unique identifier assigned to a device on a network.

34. What is the difference between IPv4 and IPv6?

• IPv4 uses a 32-bit address, while IPv6 uses a 128-bit address, providing more unique addresses.

35. What is DNS?

• DNS (Domain Name System) translates domain names into IP addresses.

36. What is a subnet mask?

• A subnet mask divides an IP address into network and host portions.

37. What is the difference between TCP and UDP?

• TCP is connection-oriented and reliable, while UDP is connectionless and faster but less reliable.

38. What is a VPN?

• A VPN (Virtual Private Network) encrypts internet connections to ensure privacy.

39. What is symmetric and asymmetric encryption?

• Symmetric encryption uses a single key, while asymmetric encryption uses a public-private key pair.

40. What is SQL injection?

• SQL injection is a hacking technique that exploits vulnerabilities in SQL queries to gain unauthorised access.

Cloud Computing

41. What is cloud computing?

• Cloud computing delivers computing services like storage, databases, and networking over the internet.

42. What are the types of cloud computing models?

• IaaS (Infrastructure as a Service), PaaS (Platform as a Service), and SaaS (Software as a Service).

43. What is the difference between public, private, and hybrid clouds?

• Public cloud is shared across multiple users, private cloud is dedicated to one organisation, and hybrid cloud combines both.

44. What is virtualization in cloud computing?

• Virtualization creates virtual instances of hardware, OS, or storage to optimize resource usage.

45. What is AWS, Azure, and Google Cloud?

• These are leading cloud service providers offering infrastructure and platform services.

46. What is the role of a hypervisor in cloud computing?

• A hypervisor allows multiple virtual machines (VMs) to run on a single physical machine.

47. What is serverless computing?

• Serverless computing allows developers to run applications without managing server infrastructure.

48. What is containerization?

• Containerization packages applications and dependencies together for consistency across environments.

49. What is Kubernetes?

• Kubernetes is an open-source tool for automating container deployment, scaling, and management.

50. What is cloud elasticity?

• Elasticity refers to the ability to scale computing resources up or down based on demand.

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Artificial Intelligence & Machine Learning

51. What is artificial intelligence (AI)?

• AI is the simulation of human intelligence in machines, enabling them to learn, reason, and solve problems.

52. What is machine learning (ML)?

• ML is a subset of AI that allows computers to learn patterns from data without explicit programming.

53. What are the types of machine learning?

• Supervised learning, unsupervised learning, and reinforcement learning.

54. What is the difference between AI and ML?

• AI is a broader concept of intelligent machines, while ML is a technique used to train AI models.

55. What is deep learning?

• Deep learning is a subset of ML that uses artificial neural networks for complex tasks like image recognition.

56. What is a neural network?

• A neural network mimics the human brain, consisting of layers of neurons for processing data.

57. What is the difference between classification and regression in ML?

• Classification predicts categories (e.g., spam or not spam), while regression predicts numerical values (e.g., house price).

58. What is NLP (Natural Language Processing)?

• NLP enables machines to understand and interpret human language.

59. What is an AI chatbot?

• An AI chatbot is a virtual assistant that interacts with users using NLP.

60. What is bias in AI models?

• Bias occurs when an AI model produces unfair results due to imbalanced training data.

Software Testing & Quality Assurance

61. What is software testing?

• Software testing verifies that an application meets requirements and is free of defects.

62. What is the difference between functional and non-functional testing?

• Functional testing checks specific features, while non-functional testing checks performance, security, and usability.

63. What is unit testing?

• Unit testing involves testing individual components or functions of software.

64. What is regression testing?

• Regression testing ensures that new changes do not break existing functionality.

65. What is manual testing vs. automated testing?

• Manual testing is performed by humans, while automated testing uses tools like Selenium and Playwright.

66. What is black-box testing?

• Black-box testing evaluates functionality without knowledge of internal code.

67. What is white-box testing?

• White-box testing examines internal code logic and structure.

68. What is an API test?

• API testing verifies if an API meets functionality, reliability, and performance expectations.

69. What is performance testing?

• Performance testing checks the speed, scalability, and stability of an application under load.

70. What is a test case?

• A test case is a set of steps and conditions used to verify a feature’s correctness.

DevOps & Automation

71. What is DevOps?

• DevOps combines development and operations to improve software delivery speed and quality.

72. What is continuous integration (CI)?

• CI is the practice of merging code changes frequently into a shared repository.

73. What is continuous deployment (CD)?

• CD automates the deployment process, ensuring every change is released to production.

74. What is Docker?

• Docker is a tool for creating and running lightweight, portable containers for applications.

75. What is Jenkins?

• Jenkins is a CI/CD tool used for automating build and deployment pipelines.

76. What is Ansible?

• Ansible is an automation tool for managing infrastructure and deployments.

77. What is Git?

• Git is a version control system for tracking changes in source code.

78. What is a pull request in Git?

• A pull request is a request to merge code changes into a repository.

79. What is infrastructure as code (IaC)?

• IaC automates infrastructure provisioning using code, such as Terraform and CloudFormation.

80. What is Blue-Green Deployment?

• It is a deployment strategy where two environments run simultaneously, minimizing downtime.

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Cybersecurity & Ethical Hacking

81. What is cybersecurity?

• Cybersecurity protects systems and data from cyber threats.

82. What is a brute-force attack?

• A brute-force attack attempts all possible passwords until the correct one is found.

83. What is phishing?

• Phishing is a social engineering attack that tricks users into revealing personal information.

84. What is two-factor authentication (2FA)?

• 2FA adds an extra layer of security by requiring a second verification method.

85. What is penetration testing?

• Penetration testing assesses security by simulating real-world attacks.

86. What is malware?

• Malware is malicious software that harms computers or networks.

87. What is ransomware?

• Ransomware encrypts files and demands payment for decryption.

88. What is ethical hacking?

• Ethical hacking identifies vulnerabilities before cybercriminals exploit them.

89. What is hashing?

• Hashing converts data into a fixed-length string for security purposes.

90. What is a zero-day exploit?

• A zero-day exploit targets unknown software vulnerabilities before they are patched.

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Emerging Technologies & General IT Knowledge

91. What is blockchain?

• Blockchain is a decentralized ledger used for secure and transparent transactions. Related: Blockchain

92. What is IoT (Internet of Things)?

• IoT connects physical devices to the internet for data exchange. Related: IoT

93. What is edge computing?

• Edge computing processes data near the source instead of relying on a central cloud. Related: EDGE Computing

94. What is Web 3.0?

• Web 3.0 is the next-gen internet using decentralized technologies like blockchain.

95. What is Industry 4.0?

• Industry 4.0 refers to smart manufacturing using AI, IoT, and automation.

96. What is a chatbot?

• A chatbot is an AI-powered program that interacts with users.

97. What is metaverse?

• The metaverse is a virtual world for digital interaction.

98. What is quantum computing?

• Quantum computing uses quantum bits (qubits) for faster processing. Related: Quantum Computing

99. What is data science?

• Data science analyzes large datasets to extract insights.

100. What is big data?

• Big data refers to extremely large datasets that require advanced processing techniques.