[ntp:questions] ntpdate works, but ntpd doesn't (reach = 0)

Martin Burnicki martin.burnicki at meinberg.de
Wed Feb 11 08:29:21 UTC 2009

Danny Mayer wrote:
> Uwe Klein wrote:
>> Richard B. Gilbert wrote:
>>> Uwe Klein wrote:
>>>> See:
>>>> currently on SuSE systems 'rcntpd restart' is run on any interface
>>>> changes.
>>> Looks like a SuSE problem rather than an ntpd problem!
>> Not really distribution specific. Look into the ip_up/down stuff
>> on any linux system.
>> Its a dynamic IP problem and its a ntpd problem due to no
>> signaling path for interface changes.
>> ( there have been some improvements very recently? )
>> uwe
> ntp 4.2.4 supports dynamic interfaces even if it cannot detect the
> change directly. The O/S does not need to worry about this for ntpd.

This is only supported kind of reasonably since 4.2.4p5. In earlier versions
it may have taken very long time after an interface has appeared until ntpd
re-tried to use it and mobilize associations.

So there's no wonder why the Linux distributors tried to implement some
workarounds (e.g. control ntpd from ifup/ifdown) to speed things up.

There are *not* only servers running 24/7 which use NTP.

Martin Burnicki

Meinberg Funkuhren
Bad Pyrmont

More information about the questions mailing list