You have a large tcp/ip network and want to keep a host's real time clock synchronized. what protocol should you use?

NTP ( Network time protocol)

Explanation:

Network time protocol is the time server which basically works in the TCP and IP network. It rely on the UDP ( User data-gram protocol) at port 123.

NTP server is the dedicated network time protocol devices which basically use for synchronize the network.

It is basically design to synchronize the clock in the computer and across the internet network and local area network. NTP server basically maintain the quality of the reference clock time.