67) A file server uses a form of locking as a concurrency control technique. When a file is locked by a client, all attempts to use or lock the file by other clients are prevented by the server. A potential problem exists if a client requests a lock on a file and then crashes. This situation could result in the file being locked indefinitely. To prevent this from occurring, the file server starts a time whenever it sets a lock. If the timer runs out before the file is unlocked the server assumes that the client

68) At a particular time, the value of a counting semaphore is 10. It will become 7 after

69) At a particular time of computation, the value of a counting semaphore is 7. Then 20 P operations and 'x' V operations were completed on this semaphore. If the final value of the semaphore is 5, x will be

70) Trojan-Horse programs

71) Seeks analysis