Each NTP Pool server's real-time status can be seen at https://www.ntppool.org/scores/*ip_address* I can't answer questions about the monitor's source code <https://github.com/ntppool/monitor >
NTP server timestamp errors happen occasionally. Internet delays and losses are unpredictable. My paper <http://leapsecond.com/ntp/NTP_Paper_Sommars_PTTI2017.pdf> discusses such NTP time transfer issues (thanks Tom). A diverse set of servers may be desirable: Using eleven stratum 2 servers with common stratum 1 sources may not meet your requirements. If the bad guys can intercept NTP traffic timestamps can be altered, unless NTP authentication is used. [This rarely happens.] On Mon, Nov 4, 2019 at 2:51 PM Bob kb8tq <kb...@n1k.org> wrote: > Hi > > Since “rogue” servers are rare, bumping up the number of servers fairly > quickly > gets you to a very high degree of confidence. Is that 5, 7, 9, or 11? It > sounds like > a wonderful topic for somebody’s thesis or dissertation :) Given that > this is a free > resource and that the network usage is negligible even with a dozen > servers, the only > real downside is being tagged as a resource hog. > > Bob > > > On Nov 4, 2019, at 7:05 AM, Hal Murray <hmur...@megapathdsl.net> wrote: > > > > > > att...@kinali.ch said: > >> This is a pretty baseless fear. The servers in the ntp pool are > constantly > >> monitored and those that are off by more than 100ms are quickly removed > >> (within 2-3 hours, IIRC). Of course, if you are already using one of > those, > >> then the removal will not help you. But you are most likely using 3-5 > servers > >> anyways, which means ntp will remove the "rouge" server on its own. > > > > It's more complicated than that. > > > > It depends on what code you are using and how you configured things. > > > > If you are using ntpd and you said in your ntp.conf > > server <pool> > > Then it grabs one and sticks with it until you restart ntpd. > > > > In the old days, it was common to use > > server 0.pool > > server 1.pool > > server 2.pool > > server 3.pool > > That used the pool before the pool code in ntpd was working. I'm pretty > sure > > some distros set things up that way and some systems are probably still > using > > an old config file. > > > > The pool code is supposed to drop bad servers and get replacements. I'm > not > > sure of the details on what "bad" covers. It could be not responding at > all > > or it could be time not good-enough. I'll dig into the code if it > matters. > > > > > > If you aren't running ntpd (classic or ntpsec) then I don't know what > happens. > > > > > > -- > > These are my opinions. I hate spam. > > > > > > > > > > _______________________________________________ > > time-nuts mailing list -- time-nuts@lists.febo.com > > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > > and follow the instructions there. > > > _______________________________________________ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. > _______________________________________________ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.