CY-501 OS Internals for Security Support - Dec 2025 Question Paper

Under each question, How to answer lists the points an answer should cover, outlined by CampusPrep from the syllabus. Check the details against your textbook.

1. 7 Marks
   aExplain the architecture of the UNIX operating system. Discuss its major system concepts.
   How to answer

   • Layered UNIX architecture: hardware, kernel, shell, applications
   • Kernel functions: file system, process control, memory, device drivers
   • Major concepts: files, processes, interprocess communication, shell
2. 7 Marks
   bDescribe buffer cache, buffer header, and the structure of the buffer pool.
   How to answer

   • Purpose of buffer cache for disk I/O
   • Buffer header fields: device, block number, status, pointers
   • Structure of buffer pool and free lists / hash queues
3. 7 Marks
   aExplain INODES and the structure of a regular file in UNIX
   How to answer

   • Definition and contents of INODE
   • Direct, indirect, double and triple indirect blocks
   • Structure of regular file and byte stream view
4. 7 Marks
   bWrite short notes on directories, super block, and INODE assignment.
   How to answer

   • Directory as file mapping names to inode numbers
   • Super block contents: filesystem size, free lists
   • INODE assignment and allocation policy
5. 7 Marks
   aExplain the following system calls : OPEN, READ, WRITE, and CLOSE.
   How to answer

   • Purpose and syntax of OPEN, READ, WRITE, CLOSE
   • Parameters, return values and file descriptor use
   • Kernel actions and error conditions
6. 7 Marks
   bA file has permissions rwxr-xr--. Find its octal equivalent and explain CHMOD.
   How to answer

   • Break rwxr-xr-- into rwx=7, r-x=5, r--=4 => 754
   • Octal permission calculation method
   • CHMOD usage: symbolic and octal modes with example
7. 7 Marks
   aExplain process layout in system memory and process control in UNIX.
   How to answer

   • Process regions: text, data, stack, u-area, kernel stack
   • Memory layout diagram description
   • Process control: fork, exec, wait, exit, context switch
8. 7 Marks
   bDescribe process creation and signals in UNIX.
   How to answer

   • fork-exec model for process creation
   • Process states and context
   • Signals: types, generation, handling and examples
9. 7 Marks
   aExplain process scheduling and the principles of concurrency.
   How to answer

   • Scheduling objectives and priorities in UNIX
   • Scheduling algorithm and preemption
   • Concurrency principles: mutual exclusion, synchronization
10. 7 Marks
    bA semaphore is initialized to 2. If three processes try to enter the critical section, how many can enter at a time? Explain.
    How to answer

    • Counting semaphore semantics with P/V operations
    • Initial value 2 allows two processes concurrently
    • Third process blocks until one exits; calculation
11. 7 Marks
    aExplain access control, auditing, and trusted computing in operating systems.
    How to answer

    • Access control models: DAC, MAC, RBAC
    • Auditing for accountability and intrusion detection
    • Trusted computing base and trust concepts
12. 7 Marks
    bDiscuss different types of malwares such as viruses, worms, Trojans, rootkits, and ransomware.
    How to answer

    • Characteristics of viruses, worms, Trojans
    • Rootkits hiding and ransomware extortion
    • Propagation and countermeasures examples
13. 7 Marks
    aExplain common vulnerabilities and exposures. What is meant by secure system configuration?
    How to answer

    • CVE concept and examples of vulnerabilities
    • Exposures and attack surface
    • Secure system configuration: hardening, patching, least privilege
14. 7 Marks
    bDiscuss virtualization techniques for security and security issues in mobile operating systems, especially Android.
    How to answer

    • Virtualization types: full, para, container for isolation
    • Security benefits: sandboxing, snapshots
    • Android issues: permissions, malware, fragmentation
15. 7 Marks
    aExplain Windows operating system architecture and important Windows internals
    How to answer

    • Windows layered architecture: HAL, kernel, executive
    • User vs kernel mode and subsystems
    • Important internals: processes, threads, registry, I/O manager
16. 7 Marks
    bDescribe sockets and Winsock. Differentiate between stream sockets and datagram sockets.
    How to answer

    • Socket concept and Winsock API
    • Stream sockets: TCP, connection-oriented
    • Datagram sockets: UDP, connectionless; differences table