[ntp:questions] Poll timing

Jussi Kauppinen jtkauppi at cc.hut.fi
Thu Aug 16 08:36:30 UTC 2007


Hal Murray wrote:
> In article <46c4022d$0$27838$39db0f71 at news.song.fi>,
>  Jussi Kauppinen <jtkauppi at cc.hut.fi> writes:
> 
>>I'm interested in exact polling moments of NTP client. Consider for 
>>example that I have polling interval set fixed to 16 seconds. Are the 
>>requests sent instantly as the second of the clock of the client 
>>changes? For example: previous polling time: 12.30:40:00, next polling 
>>time: 12.30:56:00. I mean that polling happens always as xx.xx:xx:99 
>>changes to xx.xx:xx:00. For example not like this: prev poll: 
>>12.30:40:78, next poll: 12.30:56:78.
> 
> 
> Fire up your favorite ethernet spy program and see what it says.
> 

Done that. Seems to be that polling phase is not fixed inside a second. 
Next question: How NTP daemon decides polling phase? Is it dependent on 
the moment when NTPD is launched. For example if NTPD is started at 
12.30:40:78, the first polling instant will be 12.30:56:78 (in 16 sec 
fixed polling interval).




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