The concept of client-server technology is slightly advanced than NAS. Here, if there are 10 computers on a network, nine of them work as terminals or clients, and one computer is made the server. This server stores the data of all the computers on the network with daily archiving and backup functions. This is mainly for small businesses. However, for large networks, there has to be a different server room wherein server devices are kept. Also, local machines or clients do have some data storage facility. So, the data is saved locally along with its backup on the server. These servers come with a built-in firewall, and hence are more secure. These are more flexible and allow the installation of third-party software. You need to have expert staff to work as administrators for these servers and their database. The updates and installations here may take a bit longer and need to done periodically. Also, they are more expensive compared to NAS.