When group communication is present, some method is needed for creating and deleting groups, as well as for allowing processes to join and leave groups. One possible approach is to have a group server to which all these requests can be sent. The group server can then maintain a complete data base of all the groups and their exact membership, however shares a major disadvantage with all centralized techniques: a. it has a single point of failure. b. it is hard to implement. c. it requires operating system customization. d. it requires programming. Most network layers offer reliable point-to-point channels, but they rarely offer reliable communication to a collection of processes. a. true b. false In a given process group, one process is the coordinator and all the others are workers. In this model, when a request for work is generated, either by an external client or by one of the workers, it is sent to the coordinator. The coordinator then decides which worker is best suited to carry it out, and forwards it there. This approach is called: a. arbitrary b. hierarchical The distributed commit problem involves having an operation being performed by each member of a process group, or none at all. a. true b. false Adding extra bits to allow recovery from garbled bits is called information redundancy. a. true b. false