Consider cluster have 3 nodes with Keyspaces A having replicas=3 and consistency is quorom
When 2 nodes goes down, This would throw exception that consistency level doesn't met. Does 3rd node acts as a coordinator node and save the hint for some period and replay it once they are available?
Whether hints are managed even after consistency condition doesn't met?
No, the hint is not saved because the CL is not met. Hints are not included in the CL, so since you have 2 nodes out of 3 down, the quorum CL is not met and the driver will receive an UnavailableException from the coordinator.
The write will not be tried at all because there are not enough replicas available to satisfy the required consistency.
Even if the last surviving node gets picked as the coordinator, it will not store a hint. This is explained in a bit more detail in Hinted Handoff: repair during write path. We also have a video extracted from the DS201 Cassandra Foundations course at the DataStax Academy explaining the key concepts that might be of interest to you. Cheers!
