Solve ntp error no server suitable for synchronization found

When using ntpdate -d to query, you will find the following two errors that cause no server suitable for synchronization found:

Error 1.Server dropped: Strata too high

Run ntpdate serverIP on the ntp client, and no server suitable for synchronization found error.

Check with ntpdate –d serverIP on the ntp client and find the error "Server dropped: strata too high" and display <;stratum 16”. Under normal circumstances, the value range of stratum is <; 0~15”.

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

The following definition is to keep the NTP server synchronized with itself. If the server defined in /ntp.conf is unavailable, the local time will be used as the ntp service to the ntp client.

server 127.127.1.0fudge 127.127.1.0 stratum 8

After restarting the ntp service on the ntp server, the ntp server itself or its server needs a period of synchronization, this process may be 5 minutes, within this time when the client runs the ntpdate command will generate no server suitable for synchronization found error.

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

Use the command on the ntp server:

# watch ntpq -p

The screen appears:

Every 2.0s: ntpq -p Thu Jul 10 02 :28:32 2008

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< Br>

LOCAL(0) LOCAL(0) 10 l 21 64 1 0.000 0.000 0.001

Note that this LOCAL is the ntp server that is synchronized with itself.

Note the value of reach. After starting the ntp server service, this value will increase from 0. When it is increased to 17, the change from 0 to 17 is 5 times, and each time is the value of poll. The number of seconds is 64 seconds * 5 = 320 seconds.

If you still fail to synchronize the ntp server from the ntp client, use ntpdate –d to query the detailed error message and 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.....28 Jul 17:42:24 ntpdate[14148]: no server suitable for synchronization found

The reason for this problem There may be 2:

1. Check the version of ntp. If you are using ntp4.2 (including 4.2) and later, using notrust in the definition of restrict will cause the above error.

Check the ntp version with the following command:

# 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 intend "Don't trust this host/subnet for time".

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

Resolve:

Remove the notrust.

2. Check the firewall of the ntp server. It may be that the firewall of the server blocks the upd 123 port.

You can use the command

#service iptables stop

to turn off the iptables service and then try to synchronize from the ntp client. If successful, it proves to be a firewall problem and needs to be changed. Iptables settings.