Basic CS-Operating System [TCS Placement]: Sample Questions 21 - 22 of 35

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Question 21

Operating System

Describe in Detail


When is a system in safe state?


  • If the system can allocate resources to the process in such a way that it can avoid deadlock- system is then in a safe state.
  • The set of dispatch able processes is in a safe state if there exists at least one temporal order in which all processes can be run to completion without resulting in a deadlock.
  • When a process requests an available resource, system must decide if immediate allocation leaves the system in a safe state.
  • System is in safe state if there exists a safe sequence of all processes.
  • A state is safe is the system can allocate resources to each process in some order and still avoids a deadlock.
  • More formally, a system is in a safe state only if there exists a safe sequence.
Given the Image is Defining the Example of Safe State

Question 22

Operating System

Describe in Detail


What are the stipulations of level security?


C2 level security provides for:

Discretionary Access Control

  • Discretionary access control (DAC) is a type of security access control that grants or restricts object access via an access policy determined by an object՚s owner group and/or subjects.
  • DAC mechanism controls are defined by user identification with supplied credentials during authentication, such as username and password.
  • DACs are discretionary because the subject (owner) can transfer authenticated objects or information access to other users.
  • In other words, the owner determines object access privileges.
Given the Image is Define the Discretionary Access Control (DAC)

Identification and Authentication

  • Identification is the ability to identify uniquely a user of a system or an application that is running in the system.
  • Authentication is the ability to prove that a user or application is genuinely who that person or what that application claims to be.
  • For example, consider a user who logs on to a system by entering a user ID and password.
  • The system uses the user ID to identify the user.
  • The system authenticates the user at the time of logon by checking that the supplied password is correct.
Given the Image is Define the Identification and Authentication
  1. Auditing
    • A computer security audit is a manual or systematic measurable technical assessment of a system or application.
    • Manual assessments include interviewing staff, performing security vulnerability scans, reviewing application and operating system access controls, and analyzing physical access to the systems.
  2. Resource Reuse
    • Reusable resource a resource, such as a CPU or tape transport, that is not rendered useless by being used.
    • A magnetic disk or tape can be used often indefinitely and are to be regarded as reusable resources. Compare consumable resource.
Given the Image is Define the Reusable Resource Example

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