[ntp:questions] xntpd related querries

Richard B. Gilbert rgilbert88 at comcast.net
Thu Nov 23 13:25:37 UTC 2006


lulu wrote:
> Dear Sir/Madam
> 
> I am a newbie to the ntp protocol. I read about this and try accumulate
> some aspect about it
> Please let me whether I am right or wrong.
> 
> NTP is a protocol which helps in synchronising our system clock with
> respect to a reference clock.
> 
> So what I tried taken three system in a LAN which have all the xntpd
> installed in it. All the
> related utilities also present like ( ntpq , ntpdc etc..)
> 
> Taken one system (say A (131.222.32.232) ) configured the  ntp.conf
> file by putting one entry
> like :
> peer 131.222.32.3
> peer 131.222.32.229
> driftfile /etc/inet/ntp.drift
> 
> Then other two systems has similarly ntp.conf file as follows :
> 
> System B ( 131.222.32.3)
> 
> server 131.222.32.232
> driftfile /etc/inet/ntp.drift
> 
> System C (131.222.32.229)
> 
> server 131.222.32.232
> driftfile /etc/inet/ntp.drift
> 
> Then I started the deamon xntpd in the server with the debuging option
> on i.e. "-d".
> But I dont find the time of system B and C are not geting updated with
> that of System A ( server)
> The above assumption is mine. Because what I think System B and Sytem C
> will think Syetem A
> to be their server to update which it is not doing 
> 
> Any answer ????
> 

I think you missed or misunderstood one very important point!  NTP is 
intended to synchronizes clocks to UTC rather than to a "reference 
clock".  The "reference clock" is generally a cesium frequency standard 
operated by a national standards laboratory.  Access to this clock may 
be obtained via radio, telephone, or the internet.

You seem to have told three systems, none of which knows what time it 
is, to get time from each other.  Now there is a white paper from Sun 
Microsystems that suggests that three systems configured as peers will 
converge to a common, but not necessarily correct, time.  I have not 
tried this and see no point to such an exercise.

You need either a hardware reference clock such as a GPS timing 
receiver, HF receiver or VLF receiver capable or receiving a time signal 
broadcast from a national standards lab or at least one internet server 
that gets its time from such a clock.




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