Q.1 Which of the following is the primary goal of operating system security mechanisms?
Efficiency
Data protection
User interface design
Resource scheduling
Explanation - The main purpose of OS security is to protect data and resources from unauthorized access or modification.
Correct answer is: Data protection
Q.2 What is the purpose of an access control list (ACL)?
Scheduling processes
Defining which users can access which resources
Allocating memory
Managing deadlocks
Explanation - ACLs specify permissions for users and groups over system objects like files and directories.
Correct answer is: Defining which users can access which resources
Q.3 Which mechanism ensures that users access only the resources they are authorized for?
Virtual memory
Access control
Paging
Deadlock prevention
Explanation - Access control restricts resource use to authorized users or processes only.
Correct answer is: Access control
Q.4 The principle of 'least privilege' in operating systems means:
Giving users unlimited access
Providing users the minimum access needed
Allowing root access to everyone
Disabling user restrictions
Explanation - Least privilege reduces risks by ensuring users can only perform tasks essential for their roles.
Correct answer is: Providing users the minimum access needed
Q.5 Which of these is NOT a security threat to an operating system?
Virus
Worm
Deadlock
Trojan horse
Explanation - Deadlock is a resource management issue, not a security threat.
Correct answer is: Deadlock
Q.6 Which OS component enforces security policies?
Kernel
Compiler
Scheduler
Device driver
Explanation - The kernel enforces security policies since it controls access to hardware and resources.
Correct answer is: Kernel
Q.7 What does authentication verify?
Who the user is
What the user can access
When the user logged in
How fast the system runs
Explanation - Authentication ensures the identity of the user by mechanisms like passwords or biometrics.
Correct answer is: Who the user is
Q.8 What does authorization determine?
Who the user is
What resources the user is allowed to use
System boot sequence
Network latency
Explanation - Authorization defines user rights and permissions after authentication is done.
Correct answer is: What resources the user is allowed to use
Q.9 Which of these is an example of biometric authentication?
Password
Fingerprint
Captcha
PIN
Explanation - Biometric authentication uses unique physical characteristics like fingerprints or iris scans.
Correct answer is: Fingerprint
Q.10 Which of these is a discretionary access control mechanism?
Mandatory access control
Role-based access control
Access control lists
Multilevel security
Explanation - ACLs allow resource owners to set permissions, hence discretionary in nature.
Correct answer is: Access control lists
Q.11 Which type of malware disguises itself as legitimate software?
Worm
Trojan horse
Virus
Rootkit
Explanation - Trojans mislead users by appearing as safe software but contain malicious code.
Correct answer is: Trojan horse
Q.12 In operating systems, protection domains define:
Memory size
CPU allocation
Set of resources accessible to a process
Network speed
Explanation - Protection domains specify the rights and resources processes can access.
Correct answer is: Set of resources accessible to a process
Q.13 What is the role of encryption in OS security?
Speeding up processing
Protecting data confidentiality
Managing multitasking
Reducing memory usage
Explanation - Encryption prevents unauthorized access to data by converting it into unreadable form.
Correct answer is: Protecting data confidentiality
Q.14 Which attack involves overwhelming a system with requests to make it unavailable?
Phishing
Denial of Service
Trojan horse
Brute force
Explanation - DoS attacks flood resources with traffic, making them inaccessible to legitimate users.
Correct answer is: Denial of Service
Q.15 Which of these ensures integrity of files in an operating system?
Checksums
Scheduling
Deadlock detection
Paging
Explanation - Checksums verify file contents have not been altered or corrupted.
Correct answer is: Checksums
Q.16 What is the function of an intrusion detection system (IDS)?
Allocating CPU resources
Detecting unauthorized system access
Managing memory
Scheduling jobs
Explanation - IDS identifies and reports suspicious or unauthorized activities.
Correct answer is: Detecting unauthorized system access
Q.17 Which of the following is an example of two-factor authentication?
Password only
PIN only
Fingerprint only
Password + OTP
Explanation - Two-factor authentication combines two different verification methods like password and OTP.
Correct answer is: Password + OTP
Q.18 Which of these is NOT part of the CIA triad in security?
Confidentiality
Integrity
Availability
Authenticity
Explanation - The CIA triad includes Confidentiality, Integrity, and Availability, not authenticity.
Correct answer is: Authenticity
Q.19 What is sandboxing in operating systems?
A memory management scheme
Restricting application execution to a safe environment
A scheduling algorithm
A caching mechanism
Explanation - Sandboxing isolates applications to minimize damage if they are compromised.
Correct answer is: Restricting application execution to a safe environment
Q.20 Which access control model is commonly used in military systems?
Discretionary
Mandatory
Role-based
Token-based
Explanation - Mandatory access control enforces strict policies, often used in military and government.
Correct answer is: Mandatory
Q.21 Which of these is the main purpose of auditing in OS security?
Improving performance
Tracking user activities
Allocating resources
Avoiding deadlocks
Explanation - Auditing records user and system activities for accountability and forensic analysis.
Correct answer is: Tracking user activities
Q.22 What is the role of a firewall in operating system security?
Managing processes
Filtering network traffic
Encrypting files
Controlling memory
Explanation - Firewalls block or allow network packets based on security rules.
Correct answer is: Filtering network traffic
Q.23 Which technique prevents buffer overflow attacks?
Stack canaries
Paging
Scheduling
Segmentation
Explanation - Stack canaries detect modifications to stack memory, helping prevent buffer overflow exploits.
Correct answer is: Stack canaries
Q.24 Which of these ensures non-repudiation in system security?
Digital signatures
Passwords
Firewalls
Checksums
Explanation - Digital signatures provide proof of authorship, ensuring non-repudiation.
Correct answer is: Digital signatures
Q.25 Which process ensures that old, unused credentials are not exploited?
Key revocation
Caching
Paging
Scheduling
Explanation - Key revocation ensures expired or compromised credentials are removed from the system.
Correct answer is: Key revocation