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I have referred ntpdate -d Server dropped Strata too high. This is a similar but different question.

I having two devices.

  1. Freescale ARM board (NTP server)
  2. Tinker board (client)

In the Freescale board which already installed an NTP server and the ntp.conf as below:

restrict 192.168.1.0 mask 255.255.255.0 nomodify notrap
server 127.127.1.0
fudge 127.127.1.0 stratum 8
driftfile /var/lib/ntp/drift
keys /etc/ntp/keys

Then the client didn't installed the NTP server, only use ntpdate to sync with server once.

Here is the problem:

  1. start the Freescale board NTP server $ ntpd.
  2. sync in client $ sudo ntpdate -u -d 192.168.1.10
  3. got error 192.168.1.10: Server dropped: strata too high
  4. Wait a few minutes...
  5. sync again $ sudo ntpdate -u -d 192.168.1.10
  6. this time no error

Once I $ killall ntpd and restart $ ntpd in the server, the client needs to wait a long time then$ sudo ntpdate.

For my understanding, ntpdate is used to force sync the time. Why takes so much delay time? And the error strata too high doesn't relate to the time at all.

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ntpdate does not sync the time, it steps the time once. It also will be retired in favor of ntpd and sntp commands. Do not use it on the client. Instead, configure a full NTP implementation like ntpd or chrony.

Undisciplined Local Clock, LCL refid and configured as a server matching CIDR 127.127.1.0/24, should not be used by anyone. Per NTP wiki:

The Undisciplined Local Clock should generally no longer be used.

It was originally designed to be used when an ntpd must be able to serve time to others even when no real time sources are reachable. Please see the Distribution Documentation for information about other applications for the Undisciplined Local Clock.

Users of ntp-4.2.2 and later should consider OrphanMode as a means of keeping an isolated group of servers synchronized.

The Undisciplined Local Clock is not a back-up for leaf-node (i.e. client only) ntpd instance.

On the server, replace the server line with better reference clocks: NTP over the Internet, a time appliance with a radio, or a good oscillator.

If you must run a configuration without reliable reference clocks, use orphan mode. Set a stratum threshold lower than the fudged LCL you have configured on the network, but higher than a decent Internet source, typically 1 to 3.

tos orphan 6

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