Caution: This version of this document is no longer maintained. For the latest documentation, see


Trace a chain of NTP servers


ntptrace [-dnv] [-r retries] [-t timeout] [server] 

Runs on:



Turn on debugging output.
Print only the host IP addresses, not the host names.
-r retries
Set the number of retransmission attempts for each host. The default value is 5.
-t timeout
Set the value of retransmission timeout in seconds. The default value is 2.
Print verbose information about the NTP servers.


The ntptrace utility determines the source of time for the NTP (Network Time Protocol) servers. It follows the chain of NTP servers back to their master time source. If you don't specify a server, it starts with the localhost.

$ ntptrace

Here's an example of the diagonistic output from the ntptrace utility:

localhost: stratum 4, offset 0.0019529, synch distance 0.144135 stratum 2, offset 0.0124263, synch distance 0.115784 stratum 1, offset 0.0019298, synch distance 0.011993, refid 'WWVB'

On each line, the fields are printed from left to right: the host name, the host stratum, the time offset between that host and the local host, the host synchronization distance, and the reference clock ID. Note that all times are expressed in seconds, and the time offset mentioned is not always zero. The stratum is the server hop count to the primary source, while the synchronization distance is the estimated error relative to the primary source. These terms are precisely defined in RFC 1305.


The ntptrace utility can't improve accuracy by doing multiple samples.

See also:

ntpd, ntpdate, ntpdc, ntpq

Based on RFC 1305