AKTU Operating System · Important Questions 2026Source: ryzenstudy.com PYQs
BCS401 Operating System Important Questions 2026 (AKTU)
Repeat analysis + most-asked questions, unit-wise
What we did: built from all 5 AKTU Operating System papers (2021-22–2025-26): 111 questions grouped into 73 distinct questions, 23 of which were asked in more than one paper.
- of marks were repeat questions
- 48%
- of marks were repeat questions
- questions asked in 2+ papers
- 23
- questions asked in 2+ papers
- papers analysed (2021-22–2025-26)
- 5
- papers analysed (2021-22–2025-26)
- units, mapped to current syllabus
- 5
- units, mapped to current syllabus
How much of the paper repeats?
- Repeats are real: when we checked each newer BCS401 paper against the papers before it, on average 48% of its marks were questions already asked in an earlier paper.
- 2023-24 paper: 42% of marks were repeats (5 of 9 repeated questions were in our top list).
- 2024-25 paper: 38% of marks were repeats (6 of 8 repeated questions were in our top list).
- 2025-26 paper: 64% of marks were repeats (5 of 14 repeated questions were in our top list).
- Topic weightage is a guide, not a guarantee: our Tier 1 + Tier 2 topics covered 65% of the next paper's marks — picking the same number of topics at random would have covered about 58%.
Across 10 subjects and 23 papers we tested, 43% of marks repeated earlier questions on average.
1.Unit-wise most-asked questions
Ranked by how many papers asked them, then by how recently. Click a paper to open it.
Unit 1: Introduction
17% of past marks| Question | Asked |
|---|---|
| What are the primary functions of an operating system? | Asked 4× |
| The services and functions provided by an operating system can be divided into two main categories. Briefly describe the two categories and discuss how they differ. | Asked 2× |
| What is the main advantage of the microkernel approach to system design? How do user programs and system services interact in a microkernel architecture? | Asked 2× |
| Discuss the classification of operating systems and provide real-world examples for each type. | Asked 2× |
Unit 2: Concurrent Processes
15% of past marks| Question | Asked |
|---|---|
| Define the Critical Section Problem and list the conditions that a solution must satisfy. | Asked 3× |
| What is interprocess communication? How can it be implemented? | Asked 2× |
| Define the principle of concurrency. | Asked 2× |
| Explain the dining philosopher problem and its solution using semaphore. | Asked 2× |
Unit 3: CPU Scheduling · Deadlock
28% of past marks| Question | Asked |
|---|---|
| What is a Process Control Block? Explain its role in process management. | Asked 5× |
| What are the necessary conditions for deadlock in an operating system? | Asked 3× |
| Consider the following snapshot of a system (Allocation, Max, Available: see original paper). Answer using the banker's algorithm: i. What is the content of the matrix Need? ii. Is the system in a safe state? iii. If a request from thread T1 arrives for (0,4,2,0), can the request be granted immediately? | Asked 2× |
| Consider the set of processes with arrival time, CPU burst time and priority (0 is the highest priority) given in the paper (table: see original paper). None of the processes have I/O burst time. Draw the Gantt chart and find the average waiting time using the preemptive priority scheduling algorithm. | Asked 2× |
Unit 4: Memory Management
18% of past marks| Question | Asked |
|---|---|
| Discuss multiprogramming with variable partitions and how it improves memory utilization. | Asked 3× |
| Explain the working of the Translation Lookaside Buffer (TLB) along with the page table in address translation, with a neat diagram. | Asked 2× |
| Consider the virtual page reference string (see original paper) on a demand paged virtual memory system with main memory of 4 page frames, initially empty. How many page faults will occur if the program uses: LRU and Optimal page replacement? | Asked 2× |
| What is locality of reference in demand paging? | Asked 2× |
Unit 5: I/O Management and Disk Scheduling · File System
23% of past marks| Question | Asked |
|---|---|
| Consider a disk queue with requests for I/O to blocks on cylinders 47, 38, 121, 191, 87, 11, 92, 10. The head is initially at cylinder 63, moving towards larger cylinder numbers on its servicing pass. Cylinders are numbered 0 to 199. What is the total head movement (in cylinders) if C-SCAN and C-LOOK disk scheduling are used? | Asked 4× |
| What are the advantages of using RAID architecture in disk drives? Explain in detail. | Asked 3× |
| Explain file directories and directory structures in operating systems. | Asked 3× |
| Explain the following in detail: i. Direct Memory Access ii. Interrupt iii. Polling. | Asked 2× |
2.Topic weightage: which topics carry the marks
Blue = Tier 1 + Tier 2 (topics that carried ~80% of past marks). Grey = the rest. It shows where marks have gone, not a promise of what comes next.
Process states, PCB, schedulers · U3
9.6% (cum 10%)
Paging and TLB · U4
6% (cum 16%)
Scheduling algorithms · U3
5.6% (cum 21%)
Types of operating systems · U1
4.2% (cum 25%)
Disk scheduling · U5
4.1% (cum 30%)
Deadlock avoidance, Banker's · U3
4% (cum 34%)
Page replacement algorithms · U4
3.7% (cum 37%)
Fixed and variable partitions · U4
3.7% (cum 41%)
Disk storage, seek, latency · U5
3.6% (cum 45%)
Semaphores and test-and-set · U2
3.5% (cum 48%)
RAID · U5
3.4% (cum 51%)
OS services and components · U1
3.3% (cum 55%)
Mutual exclusion, critical section · U2
3.2% (cum 58%)
I/O buffering · U5
2.9% (cum 61%)
Deadlock model and characterization · U3
2.6% (cum 63%)
OS structure and kernels · U1
2.6% (cum 66%)
Real-time and multiprocessor systems · U1
2.6% (cum 69%)
Directories and file sharing · U5
2.4% (cum 71%)
File implementation, allocation · U5
2.4% (cum 73%)
Deadlock prevention · U3
2.3% (cum 76%)
Dining philosopher, sleeping barber · U2
2.3% (cum 78%)
Multiuser, multiprocess, multithreaded · U1
2.2% (cum 80%)
OS definition and functions · U1
2.1% (cum 82%)
File protection and security · U5
2.1% (cum 84%)
IPC and process generation · U2
2% (cum 86%)
Dekker's and Peterson's solutions · U2
1.9% (cum 88%)
Scheduling concepts and criteria · U3
1.6% (cum 90%)
Fragmentation and protection · U4
1.6% (cum 91%)
File concept and operations · U5
1.5% (cum 93%)
Process concept and concurrency · U2
1.2% (cum 94%)
Thrashing, locality, cache · U4
1.1% (cum 95%)
Deadlock detection and recovery · U3
1% (cum 96%)
Virtual memory, demand paging · U4
1% (cum 97%)
Threads and management · U3
1% (cum 98%)
Bare machine, resident monitor · U4
0.6% (cum 99%)
I/O devices and subsystems · U5
0.6% (cum 99%)
Producer-consumer problem · U2
0.5% (cum 100%)
| Topic | Papers | Share |
|---|---|---|
| Process states, PCB, schedulers · Unit 3 · Tier 1 | 5/5 | 9.6% |
| Paging and TLB · Unit 4 · Tier 1 | 4/5 | 6% |
| Scheduling algorithms · Unit 3 · Tier 1 | 3/5 | 5.6% |
| Types of operating systems · Unit 1 · Tier 1 | 4/5 | 4.2% |
| Disk scheduling · Unit 5 · Tier 1 | 4/5 | 4.1% |
| Deadlock avoidance, Banker's · Unit 3 · Tier 1 | 4/5 | 4% |
| Page replacement algorithms · Unit 4 · Tier 1 | 3/5 | 3.7% |
| Fixed and variable partitions · Unit 4 · Tier 1 | 4/5 | 3.7% |
| Disk storage, seek, latency · Unit 5 · Tier 1 | 3/5 | 3.6% |
| Semaphores and test-and-set · Unit 2 · Tier 1 | 3/5 | 3.5% |
| RAID · Unit 5 · Tier 1 | 3/5 | 3.4% |
| OS services and components · Unit 1 · Tier 2 | 3/5 | 3.3% |
| Mutual exclusion, critical section · Unit 2 · Tier 2 | 3/5 | 3.2% |
| I/O buffering · Unit 5 · Tier 2 | 3/5 | 2.9% |
| Deadlock model and characterization · Unit 3 · Tier 2 | 3/5 | 2.6% |
| OS structure and kernels · Unit 1 · Tier 2 | 2/5 | 2.6% |
| Real-time and multiprocessor systems · Unit 1 · Tier 2 | 3/5 | 2.6% |
| Directories and file sharing · Unit 5 · Tier 2 | 3/5 | 2.4% |
| File implementation, allocation · Unit 5 · Tier 2 | 2/5 | 2.4% |
| Deadlock prevention · Unit 3 · Tier 2 | 2/5 | 2.3% |
| Dining philosopher, sleeping barber · Unit 2 · Tier 2 | 2/5 | 2.3% |
| Multiuser, multiprocess, multithreaded · Unit 1 · Tier 2 | 2/5 | 2.2% |
| OS definition and functions · Unit 1 · Tier 3 | 4/5 | 2.1% |
| File protection and security · Unit 5 · Tier 3 | 1/5 | 2.1% |
| IPC and process generation · Unit 2 · Tier 3 | 3/5 | 2% |
| Dekker's and Peterson's solutions · Unit 2 · Tier 3 | 2/5 | 1.9% |
| Scheduling concepts and criteria · Unit 3 · Tier 3 | 2/5 | 1.6% |
| Fragmentation and protection · Unit 4 · Tier 3 | 2/5 | 1.6% |
| File concept and operations · Unit 5 · Tier 3 | 2/5 | 1.5% |
| Process concept and concurrency · Unit 2 · Tier 3 | 2/5 | 1.2% |
| Thrashing, locality, cache · Unit 4 · Tier 3 | 2/5 | 1.1% |
| Deadlock detection and recovery · Unit 3 · Tier 3 | 1/5 | 1% |
| Virtual memory, demand paging · Unit 4 · Tier 3 | 1/5 | 1% |
| Threads and management · Unit 3 · Tier 3 | 1/5 | 1% |
| Bare machine, resident monitor · Unit 4 · Tier 3 | 1/5 | 0.6% |
| I/O devices and subsystems · Unit 5 · Tier 3 | 1/5 | 0.6% |
| Producer-consumer problem · Unit 2 · Tier 3 | 1/5 | 0.5% |
3.Paper pattern (2025-26)
| Section | Questions | Rule |
|---|---|---|
| A | 7 × 2 marks | Attempt all |
| B | 5 × 7 marks | Attempt any 3 |
| C | 10 × 7 marks | Attempt any 1 |
4.In the syllabus, never asked yet
Low priority, but read them once — a new paper can always start here.
- Segmentation, paged segmentation · U4
- File organization and access · U5
5.Study order
- 1Process states, PCB, schedulers (Unit 3, Tier 1)
- 2Paging and TLB (Unit 4, Tier 1)
- 3Scheduling algorithms (Unit 3, Tier 1)
- 4Types of operating systems (Unit 1, Tier 1)
- 5Disk scheduling (Unit 5, Tier 1)
- 6Deadlock avoidance, Banker's (Unit 3, Tier 1)
- 7Page replacement algorithms (Unit 4, Tier 1)
- 8Fixed and variable partitions (Unit 4, Tier 1)
- 9Disk storage, seek, latency (Unit 5, Tier 1)
- 10Semaphores and test-and-set (Unit 2, Tier 1)
- 11RAID (Unit 5, Tier 1)
- 12OS services and components (Unit 1, Tier 2)
- 13Mutual exclusion, critical section (Unit 2, Tier 2)
- 14I/O buffering (Unit 5, Tier 2)
- 15Deadlock model and characterization (Unit 3, Tier 2)
- 16OS structure and kernels (Unit 1, Tier 2)
- 17Real-time and multiprocessor systems (Unit 1, Tier 2)
- 18Directories and file sharing (Unit 5, Tier 2)
- 19File implementation, allocation (Unit 5, Tier 2)
- 20Deadlock prevention (Unit 3, Tier 2)
- 21Dining philosopher, sleeping barber (Unit 2, Tier 2)
- 22Multiuser, multiprocess, multithreaded (Unit 1, Tier 2)
FAQ
Which units of BCS401 carry the most marks?
Unit 3 (CPU Scheduling · Deadlock, 28% of past marks) and Unit 5 (I/O Management and Disk Scheduling · File System, 23% of past marks).
Do AKTU Operating System questions repeat?
Yes. On average 48% of the marks in each newer BCS401 paper came from questions already asked in an earlier paper, and 23 questions have appeared in more than one paper.
How is this list made?
Every question from the 5 papers (2021-22–2025-26) was mapped to the current AKTU syllabus and grouped with the same question from other years. Questions are ranked by how many papers they appeared in, then by how recently.
Study this subject
Note: this is based on past AKTU papers, not a guarantee. Questions are mapped to the current syllabus; topics that are no longer in the syllabus are left out.