Troubleshoot NTP error no server suitable for synchronization found

When querying with ntpdate-d, you will find the following 2 messages that cause no server suitable for synchronization found error:

Error 1. Server Dropped:strata too high

The NTP client runs Ntpdate ServerIP, and no server suitable for synchronization found error occurs.

The NTP client was viewed with ntpdate–d ServerIP and found "Server dropped:strata too high" error, and "stratum" is displayed. And under normal circumstances stratum This worthwhile range is "0~15".

This is because NTP server is not synchronized with itself or its server .

The following definition is to keep the NTP server in sync with itself, and if the server defined in/ntp.conf is not available, the local time will be used as the NTP service for the NTP client.

127.127. 1.0
Fudge 127.127. 1.0 Stratum 8

InNTP serverntp NTP serverserver5 minutes, run ntpdate command generates no server suitable for Synchronization Found the error.

So how do you know when NTP server has completed the process of synchronizing itself?

To use the command on an NTP server:

# Watch Ntpq-p

The screen appears:

every 2.0S:NTPQ- p                                                                                                                  Thu Jul 02:28:32

      remote           refid       St T when poll reach   delay   offset jitter

==============================================================================

192.168.30.22 LOCAL (0) 8 u 22 64 1 2.113 179133. 0.001

Local (0) local (0) ten L 21 64 1 0.000 0.000 0.001

Note that this is the NTP server that synchronizes itself with the local.

note Reach This value, when starting NTP Server After the service, this value is from 0 began to increase, when added to 17 to 17 5 change, every time Poll The value of the number of seconds is 64 seconds *5=320 seconds time.

If you later synchronize NTP server from NTP client also fails, use Ntpdate–d to query detailed error information, then make a judgment.

Error 2. Server Dropped:no Data

The error message when executing netdate–d from the client is as follows:

Transmit (192.168.30.22)

Transmit (192.168.30.22)

Transmit (192.168.30.22)

Transmit (192.168.30.22)

Transmit (192.168.30.22)

192.168.30.22:server Dropped:no Data

Server 192.168.30.22, Port 123

.....
Jul 17:42:24 ntpdate[14148]: No server suitable for synchronization found

There may be 2 reasons for this problem:

1. Check the version of NTP, if you are using a version of ntp4.2(including 4.2), using notrust in the Restrict definition will cause the above error.

Use the following command to check the version of NTP:

# ntpq-c version

The following is a description from the NTP official website:
The behavior of notrust changed between versions 4.1 and 4.2.

In 4.1 (and earlier) notrust meant "Don T trust this host/subnet for time".

In 4.2 (and later) notrust means "Ignore all NTP packets that is not cryptographically authenticated." This forces remotes servers to authenticate themselves to your (client) ntpd

Solve:

Remove the Notrust .

2. Check the firewall for NTP server. The server 's firewall may be blocking the upd 123 Port.

You can use the command

#Service iptables stop

To switch off the iptables service and then try to Synchronize from the NTP client, if successful, prove to be a firewall problem and need to change the iptables settings.

Troubleshoot NTP error no server suitable for synchronization found