Linux – What does x indicate beside NTP IP in the output of ntpq -p


Recently, I see an "x" appears beside NTP server IP in the "ntpq -p" output.

Although my server seems to be connected to the peer NTP server, it's supposed to show an "*" instead of "x" prior to the IP.

Any idea what that "x" indicates and how can I resolve the issue if it actually exists.

     remote           refid      st t when poll reach   delay   offset  jitter
x10.11.12.13   .SLK.            1 u   31   64  377    3.592  489.715   0.279
x10.13.14.15    .SLK.            1 u   63   64  377    1.527  159.577   0.400

Best Answer

The leftmost character is the "tally code". For reference, see the documentation on the Select Field values, where the T column documents the codes associated with each value.

x denotes sel_falsetick, which is described as:

discarded by intersection algorithm

Judging from your output, it looks you have two NTP servers which declare themselves as stratum 1, but do not agree on the time (i.e. the offsets differ by ~330 ms).

Since a stratum 1 time server is intended to have highly accurate time by being directly connected to a hardware reference clock, disagreement between two of them is causing your local NTP daemon to consider them both untrustworthy.