Top IBM Interview Questions & Answers for 2025

Preparing for an IBM interview in 2025 requires a solid understanding of both technical concepts and cultural fit. Whether you're applying for a technical role like software engineer or a managerial position like project manager, knowing what to expect will help you handle the interview process with confidence.

In this blog, you will explore different types of IBM interview questions and answers you may encounter. You'll cover topics such as programming, system architecture, behavioral scenarios, and IBM's values to help you excel in your interview.

Top IBM Interview Questions for Beginners and Professionals

Before exploring IBM interview questions, understanding the interview process is crucial. Knowing the steps, such as technical screenings, behavioral assessments, and cultural fit interviews, allows you to prepare effectively for each stage. This ensures you can focus on the right skills and approach the interview with confidence.

The process typically includes:

1. Application Submission: You'll begin by submitting your resume and application. Keep it concise but packed with relevant skills. Don't expect a quick turnaround. IBM tends to move at its own pace.
2. Online Assessments: Prepare to take a technical assessment or an aptitude test, depending on the role. If you're applying for a technical position, expect coding challenges or logical reasoning tests.
3. Initial Screening Call: Following the online assessments, an HR representative will contact you by phone to discuss your application. It's an introductory conversation, mainly to gauge your interest and verify your qualifications. 
4. Technical Interview: This is where things get a bit more intense. In this stage, you'll be expected to demonstrate your technical skills. You might solve coding problems or discuss algorithms. Be prepared to explain your thought process clearly and concisely.
5. Behavioral Interview: This round is focused on understanding how you fit into IBM's culture. Expect questions about teamwork, leadership, and how you've dealt with challenges. Don't give textbook answers; they want to hear about your experiences.
6. Managerial Round: Here, you'll meet someone from the team you're applying for. It's more about assessing your fit within the team and your approach to problem-solving. You may be given a practical scenario to work through.
7. Case Study/Group Discussion: Occasionally, depending on your role, you may be required to complete a case study or participate in a group discussion. They'll throw a business problem at you, and you need to figure out a solution while collaborating with others in the debate.
8. Cultural Fit Assessment: They may ask you about your work values and preferences. The company wants to see if you align with IBM's ethos, so consider how you handle various situations and challenges at work.
9. Interview with Senior Leaders: At this stage, senior leaders may want to know how you think and if you're someone they can trust with big projects. It's a high-level conversation about your career goals, motivations, and how you'd contribute to IBM.
10. Offer and Negotiation: If you've made it this far, you're likely to receive an offer. They'll share the offer details, and if you have questions about compensation or the role, this is the time to ask. If everything checks out, you'll move to the onboarding stage.

Through these stages, IBM seeks individuals who can adapt, solve problems, and succeed in diverse environments. It's not just about skills, but also about how you fit into the team.

In 2025, business professionals who can use software development skills to enhance business operations will be in high demand. To help you build these capabilities, here are some top-ranked online software development courses to guide you:

• Professional Certificate Program in Cloud Computing and DevOps
• Master of Design in User Experience
• AI-Driven Full-Stack Development Bootcamp

Now that you're familiar with the steps of the interview process, let's check out some of the top IBM interview questions for both beginners and professionals. 

1. What do you understand about procedural programming? How is it different from object-oriented programming?

How to answer:

• Start with the definition of both procedural and object-oriented programming.
• Highlight the key differences in how each paradigm structures code and solves problems.
• Mention real-world use cases to illustrate their applications.

Sample answer:

• Procedural programming focuses on a series of steps or procedures to perform tasks, typically using functions. It's well-suited for smaller projects where tasks are executed sequentially, such as in simple scripts or automation.
• Object-oriented programming (OOP), on the other hand, organizes code around objects and classes, emphasizing reusability, modularity, and scalability. OOP is preferred for larger, more complex systems because it allows for easier maintenance and extension through inheritance and polymorphism.
• Many tech companies, including IBM, favor OOP due to its ability to manage scalability and maintainability in large codebases.

2. What are the three types of schedulers in the context of operating systems? Explain.

How to answer:

• Define each type of scheduler.
• Clearly explain their roles in managing system resources and process execution.
• Use simple language and avoid unnecessary jargon.

Sample answer:

There are three main types of schedulers: long-term, short-term, and medium-term:

• Long-term scheduler controls which processes are admitted into the system, deciding which ones will run based on system resources and requirements.
• Short-term scheduler determines which process will run next by selecting from the ready queue, based on priority and available resources. It makes frequent decisions to allocate CPU time.
• Medium-term scheduler manages process swapping, deciding which processes should be moved in and out of memory to optimize resource use and prevent system overload.

Also read: Procedural Programming vs OOP - Know the Concepts

3. What do you know about virtual memory in the context of operating systems?

How to Answer:

• Define virtual memory simply.
• Explain how it uses disk space to simulate extra RAM.
• Mention its role in managing large applications and multiple programs.
• Relate it to real-world scenarios, especially in resource management.

Sample Answer:

• Virtual memory allows the operating system to use part of the hard drive as additional RAM.
• It creates the illusion of more memory, enabling the system to run larger applications or multiple programs without crashing.
• Virtual memory helps in preventing system crashes caused by memory overflow and ensures smooth performance, even under heavy workloads.
• In real-world scenarios, it’s crucial for managing resources efficiently, especially in systems with limited physical RAM, like IBM systems running complex tasks.

Also Read: Types of Memory in Computers and Their Uses with Examples

4. In the context of the C++ programming language, explain function overloading and overriding. Distinguish between them.

How to answer:

• Define function overloading and function overriding.
• Explain the differences in terms of implementation and use.
• Provide simple code examples to clarify each concept.

Sample answer:

1. Function Overloading: In C++, function overloading allows you to define multiple functions with the same name but different parameters. The compiler differentiates the functions based on the number or type of parameters.

Example:

#include <iostream>
using namespace std;

int add(int a, int b) { return a + b; }
double add(double a, double b) { return a + b; }

int main() {
    cout << add(3, 4) << endl;          // Calls int version
    cout << add(3.5, 4.5) << endl;      // Calls double version
    return 0;
}

Output:

7
8

Explanation:

• In the example, the add function is overloaded for both int and double types.
• When add(3, 4) is called, it uses the version that accepts int parameters, returning 7.
• When add(3.5, 4.5) is called, it uses the version that accepts double parameters, returning 8.

2. Function Overriding: Function overriding occurs when a derived class provides a specific implementation of a function that is already defined in its base class. The base class function must be marked as virtual for overriding to work.

Example:

#include <iostream>
using namespace std;

class Base {
public:
    virtual void display() { cout << "Base display" << endl; }
};

class Derived : public Base {
public:
    void display() override { cout << "Derived display" << endl; }
};

int main() {
    Base* basePtr;
    Derived derivedObj;
    basePtr = &derivedObj;
    basePtr->display();  // Calls Derived's display method
    return 0;
}

Output:

Derived display

Explanation:

• The display() function in the Base class is overridden in the Derived class.
• A Base class pointer (basePtr) points to a Derived object.
• The overridden display() function in Derived is called, demonstrating dynamic polymorphism.

Also read: Functions in C++: A Comprehensive Guide for Beginners

5. Differentiate between quick sort and merge sort in the context of sorting algorithms.

How to answer:

• Define both algorithms and their core principles.
• Compare their approach, time complexities, and typical use cases.
• Highlight the advantages and limitations of each.

Sample answer:

• Quicksort is a divide-and-conquer algorithm that selects a pivot to partition the array. It has an average time complexity of O(n log n) but can degrade to O(n²) in the worst case.
• Merge Sort is a divide-and-conquer algorithm that splits the array into halves and recursively merges them. It has a consistent time complexity of O(n log n) and requires additional space for merging.
• Quicksort is faster on average but unstable with certain inputs. Merge Sort is stable and performs consistently but uses more memory. Both have O(1) time complexity for insertion and deletion in ideal implementations.

6. What do you understand about a deadlock in the context of operating systems? What are the necessary conditions for a deadlock?

How to answer:

• Define deadlock in an Operating System and its impact on system performance.
• List the four necessary conditions for a deadlock to occur.

Sample answer:

Deadlock occurs when two or more processes are stuck, each waiting for the other to release a resource. This prevents system progress and can significantly slow down performance.

The four necessary conditions for a deadlock are:

• Mutual exclusion: Resources cannot be shared between processes.
• Hold and wait: A process holds one resource and waits for another.
• No preemption: Resources cannot be forcibly taken from a process.
• Circular wait: A chain of processes exists, where each process is waiting for the next in the chain.

Also Read: System Calls in Operating System (OS): What is, Types [with examples]

7. In the context of a computer, distinguish between primary and secondary memory.

How to Answer:

• Define primary and secondary memory based on speed and purpose.
• Explain the role of each in data storage and access.
• Highlight the difference in their usage within the computer system.

Sample Answer:

• Primary memory, or RAM, is fast and temporarily stores data that is actively used by the processor. It allows quick access to data, improving performance for running applications.
• Secondary memory, like a hard drive or SSD, provides long-term storage for files and programs. It’s slower than primary memory but offers much larger capacity for data that’s not needed immediately.
• While RAM improves speed and multitasking, secondary memory is essential for storing large volumes of data, such as operating systems, applications, and personal files.

Also Read: Types of Memory in Computers and Their Uses with Examples

8. What do you understand about arrays? What are some of the real-life applications of an array?

How to answer:

• Define what an array is, highlighting its structure and fixed size.
• Relate it to real-life examples to simplify the concept.
• Keep the answer focused on practical uses and its purpose.

Sample answer:

• An array is a data structure that stores a fixed-size sequence of elements, all of the same type.
• It’s like a row of mailboxes, each holding a specific value.
• Arrays are commonly used for storing student grades, managing inventory lists, or handling image pixel data. They help organize and process data quickly and efficiently.

Also read: Unlock the Power of Array in C: Master Data Handling Like a Pro

9. Differentiate between variable/ function declaration and definition in the context of any OOPs programming language.

How to Answer:

• Define the difference between declaration and definition.
• Explain their roles in the context of OOPs.
• Use clear examples to illustrate the distinction.

Sample answer:

• In OOP, a declaration tells the compiler about the variable or function’s name and type, but doesn’t assign a value or behavior.
• A definition assigns the actual value or behavior to the variable or function.
• For example, int x; is a declaration, while int x = 5; is a definition.

10. Differentiate between structs and unions in the context of the C programming language.

How to Answer:

• Define the difference between structs and unions in terms of memory usage.
• Explain how data is stored in each and when each is used.
• Use a simple, real-life example for better understanding.

Sample Answer:

• A struct allocates separate memory for each member, allowing multiple variables to hold values simultaneously.
• A union shares the same memory for all its members, meaning only one member can store a value at a time.
• Example: Use a struct to store information like a student’s name, ID, and GPA, where all values are needed at once. Use a union to store a value that can either be an integer or float, saving memory when only one type is required.

Also read: 25 Most Common C Interview Questions & Answers [For Freshers]

11. What is recursion in programming? How is it different from iteration?

How to answer:

•  Define recursion and iteration simply.
•  Explain how each approach solves problems differently.
• Mention examples where recursion is preferred.

Sample answer:
Recursion is when a function calls itself to solve smaller instances of a problem. Iteration uses loops like for or while to repeat actions.

• Recursion is useful for problems like tree traversal, factorial, or Fibonacci series where the problem can be broken into sub-problems.
• Iteration is better for simple, repetitive tasks where memory efficiency matters.
• Recursion can be elegant but may use more memory due to repeated function calls.

12. What is a linked list and how is it different from an array?

How to answer:

• Define both structures clearly.
• Compare their memory allocation and operations.
• Use practical examples.

Sample answer:
A linked list is a linear data structure where each element points to the next. It doesn’t require a fixed size and allows easy insertion and deletion.

• Arrays, on the other hand, store elements in contiguous memory and have a fixed size.
• Linked lists are better when frequent insertions or deletions are needed. Arrays are preferred for quick access using an index.
• Example: Music playlists often use linked lists for flexible reordering.

13. What is a constructor in object-oriented programming? How is it different from a method?

How to answer:

• Define a constructor and a method.
• Explain their roles and how they are used in OOP.
• Include a brief example.

Sample answer:
A constructor is a special function that runs when an object is created. It sets initial values for the object.

• A method is a regular function that performs actions on the object after it’s created.
• In C++, constructors have the same name as the class and don’t have a return type.
• For example, a Car class can have a constructor to set the model and year, and a method like start() to turn on the engine.

14. What is normalization in databases? Why is it important?

How to answer:

•  Define normalization simply.
• List its main goals.
•  Explain its role in data organization.

Sample answer:
Normalization is the process of organizing data in a database to reduce redundancy and improve integrity.

•  It involves breaking large tables into smaller ones and linking them with keys.
• This makes the database easier to maintain and reduces errors from duplicate data.
• For instance, separating customer data from orders allows updates without changing multiple records.

15. What is a stack? Give a few real-world applications.

How to answer:

• Define a stack with its basic operations.
• Explain the LIFO concept.
• Mention where it’s used in real life.

Sample answer:

• A stack is a data structure where elements are added and removed from the top. Last In, First Out (LIFO).
• It supports two main operations: push (add) and pop (remove).
• Stacks are used in undo functions in text editors, browser back buttons, and recursive function calls in programming.

16. What is a binary search algorithm? When should it be used?

How to answer:

•  Define binary search clearly.
•  Explain its requirements.
• Include where it works best.

Sample answer:
Binary search finds an element in a sorted array by repeatedly dividing the search range in half.

•  It compares the target value to the middle element and narrows the range accordingly.
• Binary search is fast, with a time complexity of O(log n), but it only works on sorted data.
• It’s ideal for looking up names in a sorted list or finding items in databases.

17. What is a class and an object in object-oriented programming?

How to answer:

• Explain class and object in simple terms.
• Show their relationship.
• Use a relatable analogy.

Sample answer:

• A class is a blueprint, and an object is a real-world example created from that blueprint.
• For example, a Car class defines properties like color and model. An object like myCar represents a specific car with actual values.
• Classes define structure and behavior, while objects bring them to life.

18. What is the difference between static and dynamic memory allocation?

How to answer:

• Define both types of memory allocation.
• Explain when and why each is used.
• Include a real example.

Sample answer:
Static memory is allocated at compile time, while dynamic memory is allocated at runtime using functions like malloc() or new.

• Static memory is fixed and doesn’t change during execution. Dynamic memory is flexible but must be managed manually.
• Example: Declaring int arr[10]; uses static memory. Using int* arr = new int[10]; uses dynamic memory.

19. What is exception handling in programming?

How to answer:

• Define exception handling simply.
• Explain why it's used.
• Mention basic keywords like try, catch.

Sample answer:
Exception handling manages errors that occur during program execution, allowing the program to continue or exit gracefully.

• It uses blocks like try, catch, and finally to handle unexpected situations like dividing by zero or missing files.
• Example: In C++, using try { riskyCode(); } catch (exception& e) { cout << e.what(); } helps prevent program crashes.

20. What is a database index and how does it work?

How to answer:

• Define what an index is in a database.
• Explain how it improves performance.
• Mention potential drawbacks.

Sample answer:
A database index is a data structure that improves the speed of data retrieval.

•  It works like an index in a book, allowing quick lookups without scanning every record.
• Indexes speed up queries but may slow down insert or update operations since the index must also be updated.

21. What is polymorphism in object-oriented programming?

How to answer:

• Define polymorphism clearly.
• Explain its types with examples.
• Keep the language simple.

Sample answer:
Polymorphism means "many forms." It allows the same function or method to behave differently depending on the context.

• There are two types: compile-time (like function overloading) and runtime (like method overriding).
• Example: A draw() method behaves differently for a Circle and a Rectangle object, depending on which class calls it.

22. What is the difference between compiler and interpreter?

How to answer:

• Define both terms.
• Compare their process and speed.
• Give examples of languages that use each.

Sample answer:
A compiler translates the entire code to machine language before running it, like in C or C++.

• An interpreter translates and runs code line by line, like Python or JavaScript.
• Compiled languages run faster, but interpreted languages are easier to debug and test.

23. What are pointers in C? Why are they useful?

How to answer:

• Define pointers clearly.
• Explain how they work with memory.
• Mention key use cases.

Sample answer:

• Pointers are variables that store the memory address of another variable.
• They allow direct memory access, making them powerful for tasks like dynamic memory allocation, arrays, and function arguments.
• Example: Using pointers helps build efficient programs like linked lists or dynamic arrays.

24. What is the difference between syntax error and runtime error?

How to answer:

• Define both types of errors.
• Explain when each occurs.
• Use examples to clarify.

Sample answer:

• A syntax error occurs when the code violates language rules, like missing a semicolon. It’s caught at compile time.
• A runtime error happens while the program is running, like dividing by zero.
• Syntax errors prevent code from compiling, while runtime errors stop it during execution.

25. What is the use of the ‘this’ keyword in object-oriented languages?

How to answer:

• Define what ‘this’ refers to.
• Explain its role in accessing current object members.
• Use a basic example.

Sample answer:

• The this keyword refers to the current object inside a class method.
• It’s used to resolve naming conflicts or to return the current object.
• Example: this->name = name; sets the object's name using the parameter passed into the method.

Now that you've gone through the IBM interview questions and answers, let's walk through how you can prepare effectively, so you feel confident.

Tips to Prepare for IBM Interview Questions

Preparing for IBM interview questions requires a solid understanding of the company’s work culture, technical requirements, and problem-solving approach. Focus on core technical concepts, such as algorithms and data structures, while also preparing for behavioral questions that assess your adaptability and teamwork skills. 

Here are some specific strategies to tackle IBM's most common interview questions.

• Know the Role Inside Out: Thoroughly read the job description to understand the required skills and responsibilities. If you don’t meet every requirement, explain how you will quickly bridge the gaps with your experience and learning ability.
• Brush Up on Your Technical Skills: For technical roles, review key topics like algorithms and data structures. Solve coding problems on platforms like LeetCode or HackerRank to refresh your skills for any technical assessments.
• Prepare for Behavioral Questions: Reflect on your past experiences with teamwork, leadership, and conflict resolution. Use the STAR (Situation, Task, Action, Result) method to structure your answers.
• Know IBM’s Culture: Research IBM's values, such as innovation, inclusion, and collaboration. Think about how your work style aligns with their culture, and prepare examples that demonstrate your fit within these values.
• Do Mock Interviews: Practice speaking about your experiences in front of a mirror or with a friend. Mock interviews help you refine your responses, improve your delivery, and reduce nervousness.
• Ask Insightful Questions: When it’s your turn to ask questions, ask about current team challenges, the tech stack they use, or how they measure success. This shows you’re genuinely interested and thinking critically about the role.

Each of these steps will help you get comfortable, build confidence, and stand out. Now, let’s understand how upGrad can help you prepare for IBM interview questions.

How Can upGrad Help You?

Preparing for IBM interview questions in 2025 means not just knowing the role but understanding how you contribute to the team. Focus on specific experiences where you solved problems, worked in teams, and handled challenges. This will help you present yourself as a solution-oriented candidate.

If you're uncertain about certain technical concepts, upGrad’s courses offer targeted, hands-on learning. You can directly work on real-world projects that address IBM’s technical needs, boosting both your skills and confidence.

Along with what you've already covered, here are some courses that can add more value to your learning journey:

• Professional Certificate Program in Data Science and AI with PwC Academy
• Learn Basic Python Programming
• Advanced JavaScript for All
• Full Stack Development Course by IIITB
• Advanced JavaScript for All

Not sure where to start or what to focus on? upGrad's career counselors can help you figure it out based on your goals. You can also drop by a nearby upGrad offline center to explore courses, try things out, and speak with mentors in person.

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