In primary-based consistency protocols, each data item in the data store has an associated primary copy, which is responsible for coordinating write operations. a. true b. false Update propagation in eventual-consistent data stores is often implemented by a class of algorithms known as epidemic protocols. a. true b. false Client-centric consistency provides guarantees for a single client concerning the consistency of accesses to a data store by that client. No guarantees are given concerning concurrent accesses by different clients. a. true b. false Caches form a special case of replication, in the sense that they are generally controlled by clients instead of servers. a. true b. false With a primary-backup protocol, whenever a process wants to perform an operation on some data item, the single copy of that data item is first transferred to the process, after which the operation is performed. This protocol essentially establishes a fully distributed nonreplicated version of the data store. Consistency is straightforward as there is always only a single copy of each data item. a. true b. false