Client/Server Computing:

Q16. A concept that is strongly related to mutual exclusion is that of a transaction. Mutual exclusion algorithms ensure that a shared resource such as a file, printer, and so on, is accessed by at most one process at a time. Transactions have the common characteristic that they also protect a shared resource against simultaneous access by several concurrent processes. a. true b. false Q17. To address clock synchronization, all of the applicable algorithms assume that the computer has access to a UTC server to query the correct time. a. true b. false Q18. Unlike the passive time server in the Berkeley model, Cristian's algorithm uses a time daemon that polls every machine from time to time to ask what time it is there. Based on the answers, it computes an average time and tells all the other machines to set their clocks to the new time. a. true b. false Q19. A nested transaction is logically a flat, indivisible transaction that operates on distributed data. a. true b. false Q20. The oldest and most widely used concurrency control algorithm is locking. a. true b. false