Fundamental to fault tolerance is the recovery from an error, replacing an erroneous state with an error-free state. a. true b. false Using timers and resending messages or replies cannot harm a distributed system. a. true b. false A key feature of scalable reliable multicasting (SRM) is that successful delivery is never acknowledged by the receiver. Only negative acknowledgements are returned as feedback. a. true b. false The cause of an error is called a fault. a. true b. false A highly reliable system may show a high degree of availability, especially if failures can be detected and repaired automatically. a. true b. false