Operating System Questions & Answers – Protection – Revocation of Access Rights

This set of Tough Operating System Questions and Answers focuses on “Protection – Revocation of Access Rights”.

1. What are the incorrect methods of revocation of access rights?
a) Immediate/Delayed
b) Selective/General
c) Partial/total
d) Crucial
View Answer

Answer: d
Explanation: None.

2. Why is it difficult to revoke capabilities?
a) They are too many
b) They are not defined precicely
c) They are distributed throughout the system
d) None of the mentioned
View Answer

Answer: c
Explanation: None.

3. What is the reacquisition scheme to revoke capability?
a) When a process capability is revoked then it won’t be able to reacquire it
b) Pointers are maintained for each object which can be used to revoke
c) Indirect pointing is done to revoke object’s capabilities
d) Master key can be used compare and revoke.
View Answer

Answer: a
Explanation: None.
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4. What is false regarding Back-Pointers scheme to revoke capability?
a) List of pointers is maintained with each object
b) When revocation is required these pointers are followed
c) This scheme is not adopted in MULTICS system
d) These point to all capabilities associated with that object
View Answer

Answer: c
Explanation: None.

5. What is true about Indirection to revoke capability?
a) Capabilities point indirectly to the objects
b) Each capability will not have a unique entry in global
c) Table entries cannot be reused for other capabilities
d) This system was adopted in MULTICS system
View Answer

Answer: a
Explanation: None.

6. How can Keys be defined or replaced?
a) create [keyname] [bits]
b) set-key
c) Key
d) MAKE [Key Name]
View Answer

Answer: b
Explanation: None.

7. What are the characteristics of the Hydra system?
a) It consists of known access rights and interpreted by the system
b) A user can of protection system can declare other rights
c) Hydra system is not flexible
d) Hydra doesn’t provide rights amplification
View Answer

Answer: a
Explanation: None.
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8. What are the characteristics of rights amplification in Hydra?
a) This scheme allows a procedure to be certified as trustworthy
b) Amplification of rights cannot be stated explicitly in declaration
c) It includes kernel rights such as read
d) All of the mentioned
View Answer

Answer: a
Explanation: None.

9. What is the problem of mutually suspicious subsystem?
a) Service program can steal users data
b) Service program can malfunction and retain some rights of data provided by user
c) Calling program can get access to restricted portion from service program
d) Calling program gets unrestricted access
View Answer

Answer: b
Explanation: Both calling program and service program are vulnerable to access each others private data/rights.
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10. What are the characteristics of Cambridge CAP system as compared to Hydra system?
a) It is simpler and less powerful than hydra system
b) It is more powerful than hydra system
c) It is powerful than hydra system
d) It is not as secure as Hydra system
View Answer

Answer: a
Explanation: None.

11. What are the two capabilities defined in CAP system?
a) data & software capability
b) address & data capability
c) hardware & software capability
d) software capability
View Answer

Answer: a
Explanation: None.

Sanfoundry Global Education & Learning Series – Operating System.

If you find a mistake in question / option / answer, kindly take a screenshot and email to [email protected]

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Manish Bhojasia - Founder & CTO at Sanfoundry
Manish Bhojasia, a technology veteran with 20+ years @ Cisco & Wipro, is Founder and CTO at Sanfoundry. He lives in Bangalore, and focuses on development of Linux Kernel, SAN Technologies, Advanced C, Data Structures & Alogrithms. Stay connected with him at LinkedIn.

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