(A) high-speed direct access storage device.
(B) low-speed direct access storage device.
(C) medium-speed direct access storage device.
(D) high-speed sequential access storage device.
Ans:-B
Explanation:-
Actually the same question is available in the book "Database systems:Concepts, Design and application" by S.K.Singh. There are lot of questions at the end of every chapter in that book. According to the book, since the head assembly is heavier, DVD and CD drives have much longer seek time as compared to magnetic-disk drives. Rotational speeds of DVD and CD drives are lower than that of magnetic disk drives. So the answer for the above question is B which is optical storage is a low speed direct access storage device.
20. Which of the following is the process by which a user’s access to physical data in the application is limited, based on his privileges ?
(A) Authorization
(B) Authentication
(C) Access Control
(D) All of these
Ans:-C
Explanation:-
In order to understand the answer for this we need to know the difference between authorization, authentication and access control. It is well explained in oracle docs.
Authentication is the process by which a user's identity is checked.
Authorization is the process by which the user's privileges are ascertained.
Access control is the process by which the user's access to physical data in the application is limited, based on his privileges.
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