Example: DHCP Client Server
Here is a very common example of the client-server programming model. The dynamic host configuration protocol or DHCP is the application responsible for requesting and offering IP addresses.
A DHCP client automatically requests an IP address from a DHCP server when a network is detected. A DHCP client could request a new IP address at any time, so the DHCP server must always be active and ready to respond to client requests. The DHCP server application typically exists in a router, but may also be found running on a network server for larger networks.