[ntp:questions] "No association ID's returned" after a period of time

Martin Burnicki martin.burnicki at meinberg.de
Thu Dec 18 13:43:08 UTC 2014

saxenaakash90 at gmail.com wrote:
> hello all,
> please help me in configuring broadcast ntp server and client.
> I have configured NTP version 4.2.6 server on fedora 20 machine. server side I am using local system time and given a broadcast subnet and all other options are disabled and on client's side I enabled only broadcast client. I haven't given server's address as according to my understanding server should broadcast NTP packets and client will automatically listen NTP packets and will get sync. but my NTP client is not syncing with server. please help me with all possibilities.

broadcast is not the default mode of operation with ntpd. You have to 
configure it explicitly both on the client *and* on the server.

Also, you need to configure symmetric keys or autokey explicitely to 
prevent your client from accepting *every* NTP broadcast packet seen on 
your network, or explicitly disable authentication.

In broadcast mode the client is unable to determine and compensate the 
network packet delay properly, so this usually yield only less accuracy 
than normal client/server mode.

If you are new to NTP you should start with the default mode of 
operation, i.e. client/server mode. If you have an NTP server on your 
network just add an appropriate "server" line to the client's ntp.conf 
file. For example

server 111.222.333.444 iburst

if your NTP server has IP address 111.222.333.444.

Is your NTP server synchronized to some other time source? If it is not 
then your NTP server will not be accepted by any real NTP client.


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