What is the function of NTP?
The Network Time Protocol (NTP) is a networking protocol for clock synchronization between computer systems over packet-switched, variable-latency data networks. In operation since before 1985, NTP is one of the oldest Internet protocols in current use.
What port does NTP use?
NTP time servers work within the TCP/IP suite and rely on User Datagram Protocol (UDP) port 123.
How does NTP client work?
The NTP client initiates a time-request exchange with the NTP server. As a result of this exchange, the client is able to calculate the link delay and its local offset, and adjust its local clock to match the clock at the server’s computer.
What is an acceptable NTP offset?
The maximum slew rate possible is limited to 500 parts-per-million (PPM) by the Unix kernel. As a result, the clock can take 2000s for each second the clock is outside the acceptable range. According to the manual page ntpd won’t work if your clock is more then 1000 seconds off.
How long does NTP sync take?
about five minutes
Where does NTP set time from?
ntpdate sets the local date and time by polling the Network Time Protocol (NTP) server(s) given as the server arguments to determine the correct time. It must be run as root on the local host.
Does NTP set time zone?
NTP does not regconize time zones, instead it manages all time informations based on UTC. In general the handling of time zones is a job of a computer’s operating system. Example: If you configure Windows to use your local time zone, the system clock continues with using UTC time.
How accurate is NTP time?
The typical accuracy on the Internet ranges from about 5ms to 100ms, possibly varying with network delays. A recent survey[2] suggests that 90% of the NTP servers have network delays below 100ms, and about 99% are synchronized within one second to the synchronization peer.
Who has the most accurate time?
The world’s most precise clock is found in the United States. The clock was built by the National Institute of Standard and Technology together with the University of Colorado, Boulder. The clock is so precise no second is lost over the entire age of the Universe.