rdate - network date client
/usr/sbin/rdate [-s] [-v] [network]
-s The system date and time will be set to the median value.
-v The time values returned by all responding hosts will be reported.
The rdate command is invoked at boot time to reset the system date and time
to the current network date and time. The rdate program sends a broadcast
datagram packet on the specified network or on the system default network
if no network is specified. The program will then wait two seconds for
responses. After that time, the arithmetic median of the responses is
In order for rdate to determine a network time, at least one of the running
hosts on the network must be running the internet time service. Machines
with their own battery-backed-up time-of-day clock may not desire to set
time in this manner.