[ntp:questions] Re: Why so many dead NTP servers in pool.ntp.org?

Bjorn Gabrielsson bg at lysator.liu.se
Tue Dec 13 22:41:39 UTC 2005

Raphae <prosolutions at gmx.net> writes:

> On Tue, 13 Dec 2005 04:37:48 +0200, Tapio Sokura <oh2kku at iki.fi>
> wrote:
> >Raphae wrote:
> >> when running the command
> >> 
> >> # ntptrace pool.ntp.org
> >> 
> >> 
> >> more than half of the servers in the pool seem to be dead.  Isn't
> >
> >Are you sure that they are dead, or just not responding to NTP control 
> >mode (mode 6) packets? Because mode 6 is what ntptrace uses, when the 
> >actual NTP time queries are sent/received using modes 1-5. All pool 
> >servers that I just tried did answer to normal time queries (mode 3) 
> >just fine. Some server operators choose to restrict mode 6 queries, that 
> >is completely acceptable by the pool rules.
> >
> Thank you for your response.  I am setting up the NTP daemon from
> ntp.org and am a bit confused.  In ntp.conf there is no mention of any
> modes.  
> Currently I have been using rdate to set my system clock using
> tick.greyware.com.  
> Now that I have installed NTP things have become more complex.  It
> seems that to configure it to be a server one also has to configure it
> to be a client to some other NTP servers.  I am not really sure what
> is the daemon and what is the client portion of this program.  The

The client is the server... ntpd is a client in that it get time from
the upstream servers you have configured in ntp.conf. Its a client in
that it will serve time to anyone that has your computer in his
ntp.conf. Its possible to block the serving part by using appropriate
'restrict' statements in ntp.conf.

> config file for the daemon has a server parameter which makes it seem
> as though it is a client.  As far as configuring it as a server - if
> for example I want it to be accessible to clients running "rdate"

rdate is another protocol than ntp. look at


> This is all so complex for a newbie.  Unfortunately also the ntp
> package doesn't contain standard man pages but refers you to html
> documentation which seems to be more theoretical in nature but not
> very useful for the practice of setting up a server.

Well, 'server your.prefered.ntp.server.com' in ntp.conf. Then start
ntpd with a 'ntpd -g'. Thats not to hard?

Its slightly more complex when you want your strange and old
gps-receiver running as a reference clock for ntpd to get its time

Assuming you are running something unix-like. Does not your OS have
ntp already?

good luck,


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