From the application's standpoint, when we issue a query to Cassandra, we simply send some CQL over the wire and, at some later point, receive a response. Hopefully, the response will return successfully; if not, we will receive an error.
One requisite for a successful response is that our query is well formed: if we misspell the name of a column, for instance, we will certainly see an error. But this condition for success is of little concern to us, since an invalid query will always generate an error, regardless of external factors.
More interesting from the perspective of consistency is the other condition of a successful request: that Cassandra is internally able to fulfill it. For a write request, ...
