The correct answer is D. all of the mentioned.
Cloud-based storage systems are highly reliable because they use a variety of features to ensure that data is always available. These features include redundant networks, redundant name servers, and replication.
Redundant networks mean that there are multiple paths for data to travel, so if one path fails, the data can still be accessed. Redundant name servers mean that there are multiple servers that can resolve domain names, so if one server fails, the other servers can still provide the correct information. Replication means that data is stored on multiple servers, so if one server fails, the data is still available on the other servers.
These features make cloud-based storage systems highly reliable, even in the event of a failure.