Client-Server Model:-

A client and server networking model is a model in which computer such as servers provide the network services to the other computer such as clients to the perform a user based tasks. The model is known as client server networking model.

An application program is known as client program, running in the local machine that requests for a service from an application program, running on the remote machine.

A client programs runs only when it requests for a service from the server while the server program runs all time as it does not know when its service is required.

A server provides a service for many clients nit just for a single client. Therefore, we can say that client-server follows the many-to-one relationship. Many clients can use the service of one server.

Service are required frequently, and many users have a specific client-server application program. For example, the client-server application program allows the user to have one generic application program that allows the user to access the services available on the remote computer.

How the Client-Server Model works ?

•Client:-  A client is a program that runs on the local machine requesting service from the server. A client program is a finite program means that the service started by the user and terminates when the service is completed. 

•Server :-  A client is a program that runs on the remote machine providing services to the clients. When the client requests for a service, then the server opens the door for incoming requests, but it never initiates the service. A server program is an infinite program means that when it starts, it run infinitely unless the problem arises. The server waits for the incoming requests from the clients, When the request arrives at the server, then it respond to the request.

So its basically the Client requesting something and the Server serving it as long as its present in the database.

Advantage of Client-Server Network

1. Centralized:- Centralized back-up is possible in client server networks i.e.,all the data is stored in a server.

2. Security:- These networks are more secure as all the shared resources are centrally administered.

3. Performance:- The use if the dedicated server increses the speed of sharing resources. This increase the performance of the overall system.

4. Scalability:- We can increase the number of clients and servers separately, i.e., the new element can be added, or we can add a new node in a network at any time.

Disadvantages of Client-Server Network

1. Traffic congestion is a big  problem in Client/Server networks. When a large number of clients send requests to the same server may cause the problem of Traffic congestion.

2. It does not have a robustness of a network, i.e., when the server is down, then the client request cannot be met.

3. A client/server network is very decisive. Sometimes regular computer hardware dies not serve a certain number of clients. In such situations, specific hardware is required at the server side to complete the work.

4. Sometimes the resources existing in the server but may not exist in client. For example, If the application is Web then we cannot take the print out directly on printers without taking out the print view window on the web