Operating Systems And Security

a) Explain OS? Define the services provided by the Operating System.

b) Differentiate between user thread and kernel thread. What is thread cancellation?

a) Explain in detail about process control block in CPU scheduling.

b) Explain in detail about the disk storage and disk scheduling.

What is a Critical Section problem? Give the conditions that a solution to the critical section problem must satisfy. A hard disk having 2000 cylinders, numbered from 0 to 1999. the drive is currently serving the request at cylinder 143, and the previous request was at cylinder 125. The status of the queue is as follows:
86, 1470, 913, 1774, 948, 1509, 1022, 1750, 130
What is the total distance (in cylinders) that the disk arm moves to satisfy the entire pending request for each of the following disk-scheduling algorithms?

1. SSTF
2. FCFS

a) Discuss Mutual-exclusion implementation with test and set () instruction. Process by specifying its various levels.

b) Is it possible to have a deadlock involving only a single process? Explain.

a) Explain what semaphores are their usage, implementation given to avoid busy waiting and binary semaphores?

b) What do you mean by security in operating system? Why it is requiring in operating system? Explain.

a) What is DOS and DDOS attack? How to prevent them?

b) What are four main components of a secure system? Explain each of them.

a) What kind of authentication Unix system use? Explain the authentication procedure.

b) Explain the term security vulnerabilities and security violations with example.

Write sort notes on the following:

1. Digital signature
2. Multics security