If the primary copy scheme is used for replication, and the primary gets disconnected from the rest of the system, a new node may get elected as primary. But the old primary may not realize it has got disconnected, and may get reconnected subsequently without realizing that there is a new primary.

a. What problems can arise if the old primary does not realize that a new one has taken over?

b. How can leases be used to avoid these problems?

c. Would such a situation, where a participant node gets disconnected and then reconnected without realizing it was disconnected, cause any problem with the majority or quorum protocols?