NTP error: no server suitable for synchronization found

problem

If we configure ntp After the service , Never sync , Carry out orders ntpdate -u serverip

Direct error ：no server suitable for synchronization found

solve

Conclusion ： It's usually ntp server There is a problem , Or else client and server The Internet is not working .

It is assumed that ntpserver Of ip yes X1

Follow the following steps to check

1. Use command ntpdate -d X1

Follow in the return message 2 A mistake ：

error 1：X1: Server dropped: strata too high

Under this error , And display “stratum 16”. And normally stratum What's the scope of this “0~15”. This is because NTP server Not with itself or its upper layer server In sync . So here we need to check ntpserver Whether the configuration is correct , such as server Is synchronized with itself , Or synchronize with the upper server , See if the configuration is correct , If the configuration is also synchronized with the upper layer server, check whether the upper layer is normal .（ Of course. ntp server On restart ntp After service ,ntp server Itself or with server It takes a period of time to synchronize , The process could be 5 minute , But it usually doesn't take so long , During this time, the client runs ntpdate Command will produce no server suitable for synchronization found Error of .） see ntpserver Whether the synchronization with itself has been completed , You can use commands ntpq -p,

Synchronization will show * Number , Otherwise, there is no .

error 2：X1: Server dropped: no data

If this error occurs , View and first ntp Whether the server can connect （ping x1）, If you can connect, you will see whether the firewall is turned on and forbidden 123 Port access , If you don't want to see it anymore ntpserver On the machine ntp Whether the service is normal （service ntpd status; ntpq -p）.

If none of the above is true, let's see if it is ntp Version issue for . such as ntp4.2（ Include 4.2） Later versions , stay restrict Used in the definition of notrust Words , Can cause the above error .