This set of Operating System Multiple Choice Questions & Answers (MCQs) focuses on “Protection – Revocation of Access Rights”.
1. 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
2. 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.
3. What are the incorrect methods of revocation of access rights?
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
5. How can Keys be defined or replaced?
a) create [keyname] [bits]
d) MAKE [Key Name]
6. 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
7. 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
8. 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
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
10. What are the two capabilities defined in CAP system?
a) data & software capability
b) address & data capability
c) hardware & software capability
d) software capability
11. 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