[ntp:questions] hello, I have a question about NTPD service in LAN use a host as time source two other host as client

unruh unruh at invalid.ca
Thu Jun 13 17:47:17 UTC 2013


On 2013-06-13, xiaoniao54321 at gmail.com <xiaoniao54321 at gmail.com> wrote:
> I?v recently start a work about NTP,it's about a ntp sync in 
> winodws LAN,no GPS,only a host as server,two host as client.But Ican't sync 
> the time ,because the server clock and reftime is not the same.I use ntpq-c 
> rv to query the time,but I,v got a different reftime and clock,especially I 
> adjust  the server time to a time before it .
>
>
> I had run ntpq -c rv on CMD.it shows lisk:
> reftime=d5639c52.13c08ef6 thu,jun 13 2012 9:18:10:077,pool=10,
> clock=d5639c68.5717350d thu,jun 13 2012 9:18:10:340,state=4,
> offset=0.000,frequency=0.000,jitter=0.000,noise=0.000,stability=0.000,tai=0
> I know that the clock above shows system clock of host as time source,
>
> but if the clock item up shows the current system time,when I changed  the clock below on the right taskbar of my system to 9:01.set local host as time source, 
>
> run ntpq -c rv on cmd but the clock item didn't changed to 9:01,that's why?

Why should it? ntpd does not simply change the time on the host to agree
with the server. It first checks for a long time to make sure that the
time from the server is really correct, and has not been corrupted (it
takes at least 8 measurement cycles to do that) only then will it jump
the clock (if it is out by more than .128 sec).

ntpd operates slowly. 

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