C-DAC Interview Questions 2026 Freshers

Introduction

C-DAC, the Centre for Development of Advanced Computing, is one of India's premier government research and development organisations under the Ministry of Electronics and Information Technology (MeitY). For engineering freshers with a passion for core computing, embedded systems, and national technology projects, landing a role at C-DAC is both prestigious and rewarding. The organisation recruits engineers across roles such as Project Engineer, Software Developer, Research Engineer, and Technical Officer through a structured written test followed by technical and HR interviews.

What sets C-DAC apart from typical IT company recruitment is the depth of core computer science knowledge expected. Unlike mass-recruitment IT firms that focus heavily on aptitude puzzles and behavioural rounds, C-DAC's selection process digs into operating systems, computer networks, database management, data structures, and low-level programming in C and C++. Freshers who have done serious coursework in their B.Tech/BE programs and can apply theory to practical scenarios tend to perform well here.

It is also important to distinguish C-DAC recruitment from C-CAT, the C-DAC Common Aptitude Test. C-CAT is an entrance examination for admission to C-DAC's postgraduate diploma courses (CDAC-ACTS, CDAC-ACTS PG Diplomas, etc.) offered at centres across India, Pune, Hyderabad, Chennai, Noida, and others. Both C-CAT aspirants and direct recruitment candidates will find this guide useful, as the technical content overlaps significantly. This article focuses on the direct recruitment interview process for freshers targeting the 2026 intake.

C-DAC Exam Pattern 2026

The C-DAC written test for direct recruitment consists of two broad sections, General Aptitude and Technical/Core CS. The exam is conducted online in an MCQ format with negative marking applicable. Candidates who clear the written test are shortlisted for technical interviews, after which HR rounds follow for final selection.

Note: Negative marking of -0.25 marks applies per wrong answer. The technical section carries the most weight in shortlisting. Cutoff typically ranges from 55–65% overall depending on the batch and role applied for.

Quantitative Aptitude Questions

The aptitude section in C-DAC is straightforward for candidates with strong basics. Questions are drawn from standard arithmetic topics and are designed to test speed and accuracy rather than complex problem-solving. Practising 20–25 questions daily in timed conditions for two weeks is usually sufficient to clear this section comfortably.

Q1. A pipe fills a tank in 12 hours and another empties it in 18 hours. If both are opened simultaneously, in how many hours will the tank be filled?

Explanation: Net filling rate = 1/12 - 1/18 = 3/36 - 2/36 = 1/36 per hour. Time = 36 hours.

Q2. The ratio of the ages of A and B is 3:5. After 10 years, the ratio will be 5:7. What is B's current age?

Explanation: Let A = 3x, B = 5x. After 10 years: (3x+10)/(5x+10) = 5/7. Cross multiply: 21x+70 = 25x+50. 4x = 20, x = 5. B = 5 × 5 = 25.

Q3. A train 240 m long passes a pole in 12 seconds. How long will it take to pass a platform 360 m long?

Explanation: Speed = 240/12 = 20 m/s. Distance to cover = 240 + 360 = 600 m. Time = 600/20 = 30 seconds.

Q4. If 15 workers complete a task in 24 days, how many workers are needed to complete the same task in 18 days?

Explanation: Total work = 15 × 24 = 360 worker-days. Workers needed = 360/18 = 20.

Q5. A shopkeeper marks an item 40% above cost price and gives a 25% discount. What is the profit or loss percentage?

Explanation: Let CP = 100. MP = 140. SP = 140 × 0.75 = 105. Profit = 5%.

Verbal Ability Questions

The verbal section tests basic English comprehension and grammar. C-DAC's verbal questions are not tricky, they focus on reading speed and understanding of standard technical/general passages. Error spotting, fill in the blanks, and vocabulary-based questions are common.

Q1. Choose the correct sentence: (a) He don't know the answer. (b) He doesn't knows the answer. (c) He does not know the answer. (d) He do not knows the answer.

Explanation: With third-person singular subjects, "does not" is correct and the verb remains in base form without "s".

Q2. Fill in the blank: The project was completed ________ schedule, which impressed the management.

(a) ahead of (b) ahead in (c) before of (d) prior in

Q3. Identify the error: "The committee have submitted (A) / their report (B) / to the chairman (C) / last Monday. (D)"

Q4. Choose the synonym of "Meticulous": (a) Careless (b) Precise (c) Hasty (d) Casual

Technical Questions

This is the section that determines shortlisting for the C-DAC interview. The 45-question technical section spans operating systems, DBMS, computer networks, C/C++ programming, data structures and algorithms, and software engineering concepts. Questions test both conceptual understanding and practical application.

Q1. What is the difference between a process and a thread?

Q2. What is a deadlock? State the four necessary conditions for deadlock to occur.

• Mutual Exclusion: At least one resource must be held in a non-shareable mode
• Hold and Wait: A process holds at least one resource and is waiting to acquire additional resources held by other processes
• No Preemption: Resources cannot be forcibly taken from a process; they must be released voluntarily
• Circular Wait: A circular chain of processes exists where each process waits for a resource held by the next process in the chain

Q3. Explain the difference between TCP and UDP with use cases.

Q4. Write a C program to reverse a linked list.

#include <stdio.h>
#include <stdlib.h>

struct Node {
    int data;
    struct Node* next;
};

struct Node* reverseList(struct Node* head) {
    struct Node* prev = NULL;
    struct Node* curr = head;
    struct Node* next = NULL;
    while (curr != NULL) {
        next = curr->next;
        curr->next = prev;
        prev = curr;
        curr = next;
    }
    return prev;
}

Explanation: Three pointers are used, prev, curr, and next. At each iteration, the next pointer of curr is reversed to point to prev. Time complexity: O(n), Space complexity: O(1).

Q5. What is normalization in DBMS? Explain 1NF, 2NF, and 3NF.

• 1NF: Each column contains atomic (indivisible) values; no repeating groups. Each row is unique.
• 2NF: Satisfies 1NF + every non-key attribute is fully functionally dependent on the entire primary key (no partial dependency). Applies only when the primary key is composite.
• 3NF: Satisfies 2NF + no transitive dependency (non-key attributes should not depend on other non-key attributes).

Coding Round Questions

C-DAC's technical interview often includes one or two coding problems to be solved on paper or a whiteboard. The focus is on correctness of logic and efficiency, not on competitive-programming-level difficulty.

Problem 1: Write a function to check if a given string is a palindrome.

#include <string.h>
int isPalindrome(char* str) {
    int left = 0, right = strlen(str) - 1;
    while (left < right) {
        if (str[left] != str[right]) return 0;
        left++;
        right--;
    }
    return 1;
}

Problem 2: Find the second largest element in an array without sorting.

int secondLargest(int arr[], int n) {
    int first = INT_MIN, second = INT_MIN;
    for (int i = 0; i < n; i++) {
        if (arr[i] > first) {
            second = first;
            first = arr[i];
        } else if (arr[i] > second && arr[i] != first) {
            second = arr[i];
        }
    }
    return second;
}

Time complexity: O(n). Single pass through the array.

Problem 3: Implement a stack using two queues.

The key idea: push operation enqueues to q1 normally. For pop, dequeue all elements from q1 to q2 except the last, return the last, then swap q1 and q2. Push O(1), Pop O(n).

Problem 4: Write a function to detect a cycle in a linked list (Floyd's algorithm).

int hasCycle(struct Node* head) {
    struct Node* slow = head, *fast = head;
    while (fast != NULL && fast->next != NULL) {
        slow = slow->next;
        fast = fast->next->next;
        if (slow == fast) return 1;
    }
    return 0;
}

Interview Process at C-DAC

The C-DAC recruitment process for freshers in 2026 follows a structured multi-stage approach:

• Stage 1, Online Application: Applications are submitted through C-DAC's official recruitment portal. Candidates with B.Tech/BE in CS, IT, Electronics, or related disciplines are eligible. Shortlisting is done based on academic percentage (typically 60% or above throughout).
• Stage 2, Written Test: Online MCQ-based test covering aptitude and core CS topics. Conducted at designated centres or remotely. Duration: approximately 100 minutes. Negative marking applies.
• Stage 3, Technical Interview Round 1: Panel of 2–3 technical experts. Questions focus on the candidate's domain knowledge, OS, CN, DBMS, C/C++, embedded systems (for hardware roles), and project work. Typically 30–45 minutes.
• Stage 4, Technical Interview Round 2 (for senior/research roles): Deeper dive into specialised areas, research publications, or advanced technical topics. Not always conducted for Project Engineer roles.
• Stage 5, HR Interview: General HR questions, career goals, willingness to relocate to C-DAC centres, service agreement discussion. C-DAC roles often come with a service bond of 1–2 years.
• Stage 6, Document Verification and Medical: Standard government process before final offer release.

Tips to Crack C-DAC Interview

• Master OS fundamentals: Process management, memory management, scheduling algorithms (FCFS, SJF, Round Robin, Priority), deadlock handling, and virtual memory are almost always asked. Go through Galvin's OS textbook.
• C and C++ are non-negotiable: Be comfortable with pointers, dynamic memory allocation (malloc/calloc/realloc/free in C), OOP concepts (inheritance, polymorphism, virtual functions) in C++, and common bugs like memory leaks and dangling pointers.
• Data structures from scratch: Be ready to implement linked lists, stacks, queues, BSTs, and heaps on paper. Know time and space complexities for all standard operations.
• DBMS, SQL queries are tested: Practice writing SQL queries including JOINs, subqueries, GROUP BY, HAVING, and aggregate functions. Understand transactions, ACID properties, and isolation levels.
• Computer Networks, layer-wise clarity: Know the OSI and TCP/IP models layer by layer. Understand subnetting, CIDR notation, DNS, HTTP, ARP, and routing protocols (RIP, OSPF) at a conceptual level.
• Practise C-CAT previous papers: Even for direct recruitment, C-CAT papers are an excellent source of C-DAC-style technical questions and help calibrate your preparation level.
• Projects matter: Interviewers at C-DAC appreciate candidates who have done meaningful technical projects, embedded systems, OS mini-projects, networking tools, or system-level programming. Be ready to explain your final year project in depth.
• Communication in English: C-DAC is a government R&D body but technical communication in English is expected during interviews. Practice articulating technical concepts clearly.
• Understand C-DAC's work: Familiarise yourself with C-DAC's flagship products and projects, PARAM supercomputers, Aakash tablet, BOSS Linux, NavIC applications, HealthCube. Mentioning awareness of their work creates a positive impression.
• Negative marking awareness: In the written test, avoid guessing blindly. Attempt questions where you are at least 70% confident. Leave the rest blank.

Common HR Interview Questions

Q1. Why do you want to join C-DAC over private IT companies?

Sample Answer: C-DAC works on projects that directly impact national infrastructure and technology sovereignty, from supercomputing to healthcare applications. I want to be part of technology that solves real problems at scale for India rather than building commercial software for a single business. The opportunity to work with domain experts on cutting-edge research is something private IT firms cannot easily offer at the fresher level.

Q2. Are you comfortable relocating to any C-DAC centre?

Sample Answer: Yes, absolutely. I understand C-DAC has centres in Pune, Hyderabad, Chennai, Noida, Kolkata, and other cities. I am open to being posted at any centre based on project requirements. Flexibility is something I consider an advantage, not a constraint.

Q3. How do you handle situations where you are stuck on a technical problem for a long time?

Sample Answer: I break the problem down into smaller components and try to isolate which part is causing the issue. I refer to documentation, relevant research papers, or online resources. If I'm still stuck after genuine effort, I reach out to a colleague or mentor, I don't believe in suffering in silence when team efficiency is at stake.

Q4. What is your greatest technical strength and how will it benefit C-DAC?

Sample Answer: My strongest area is systems programming, I have worked extensively with C and have built small OS kernel modules as part of academic projects. C-DAC's work on embedded systems and system-level software directly aligns with this strength. I can contribute to low-level development tasks with minimal ramp-up time.

Q5. What is your long-term career goal?

Sample Answer: I want to grow as a systems and embedded software engineer, contributing to national-level technology projects. Over the next five years, I aim to specialise in areas like real-time operating systems or high-performance computing, and eventually take on a technical lead or research scientist role within C-DAC or a similar organisation.

Salary Package Information

The figures below are candidate-reported and indicative only. C-DAC roles follow government pay structures that are revised by pay commission cycle and vary by centre and role, so confirm the exact numbers against the official C-DAC recruitment notification for your applied post.

Additional Benefits: HRA (house rent allowance), TA/DA for official travel, medical coverage under CGHS, provident fund, gratuity, leave encashment, LTC (Leave Travel Concession), and access to C-DAC's internal training and certification programs. Roles may include a service bond of 1–2 years with a refundable bond amount.

Preparation Strategy

Weeks 1–2, Core CS Foundation: Revise OS (Galvin), DBMS (Ramakrishnan/Navathe), and Computer Networks (Forouzan/Tanenbaum). Focus on conceptual clarity, not rote memorisation. Make one-page cheat sheets for each topic.

Week 3, C and C++ Programming: Revise pointers, memory management, file I/O, structures, and OOP in C++. Write programs from scratch without an IDE. Practice explaining code line by line.

Week 4, Data Structures and Algorithms: Implement all major data structures in C. Practice algorithm design, sorting, searching, graph traversal (BFS/DFS), dynamic programming basics. Know time complexities cold.

Week 5, Aptitude and Verbal: Solve 30 aptitude questions daily from standard placement prep books. Focus on accuracy over speed initially, then time yourself. Ten minutes daily on verbal, error spotting, vocabulary.

Week 6, Mock Tests and C-CAT Papers: Take full-length mock tests under timed conditions. Solve C-CAT previous years' papers (available on official C-DAC website and prep portals). Identify weak areas and revisit.

Week 7, Interview Preparation: Practice explaining your projects out loud. Conduct mock technical interviews with peers. Research C-DAC's current projects and prepare to discuss them. Practise coding on paper.

Week 8, Final Revision and Mindset: Light revision of all cheat sheets. Ensure documentation (marksheets, certificates, ID proofs) is ready. Sleep adequately before the exam/interview day.

Conclusion

C-DAC recruitment is a genuinely competitive process that rewards candidates with strong fundamentals rather than those who have simply crammed interview tips. The written test filters out a significant chunk of applicants, and the technical interview panel at C-DAC comprises experienced researchers and engineers who can spot surface-level knowledge quickly. Authentic understanding of OS, networking, DBMS, and C/C++ is your primary weapon.

The salary at C-DAC may not match top-tier private IT firms at the fresher level, but the nature of work, contributing to supercomputers, defense-grade software, and national digital infrastructure, provides a depth of technical experience that is hard to match elsewhere. Many C-DAC engineers go on to pursue advanced research, IIT/NIT M.Tech programs with GATE scores, or transition to high-paying roles in embedded systems and systems programming after gaining experience.

Start your preparation at least 8–10 weeks before the expected exam date, stay consistent with daily practice, and approach the technical interview as a conversation with a fellow engineer rather than an interrogation. C-DAC values intellectual honesty, saying "I'm not sure but here's how I'd think about it" is far better than bluffing.

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