Timo Ruiter wrote: > Timo Ruiter schreef: > >> Hi all, >> >> When using pool.ntp.org the DNS randomly select time servers. Since >> stratum-1 servers and stratum-2 servers share the same pool you will >> get a mix of them when using 0.nl.pool.ntp.org, 1.nl.pool.ntp.org, and >> 2.nl.pool.ntp.org for instance. >> When you are assigned *one* stratum-1 server and *two* stratum-2 >> servers your clock will obviously synchronize to the stratum-1 server. >> But that being the case, what is the use of the two stratum-2 servers, >> assuming that the stratum-1 server will not go off-line? >> Could it be so that if the stratum-1 server is not so accurate after >> all it would still be selected over the stratum-2 servers (since no >> reference stratum-1 server is available)? >> Will you not be better served instead when you are assigned *three* >> stratum-2 servers, so the selection process of ntpd will compare all >> three servers equally and choose the best one, switching to another if >> that one looks more stable after a while? >> >> >> Regards, >> Timo > > What I really wanted to know is what is better in terms of stability: > *one* stratum-1 server and *two* stratum-2 servers versus *three* > stratum-2 servers. > When having only one stratum-1 server available you might be relying on > that server too much; when having three stratum-2 servers (ideally > synchronized to three different stratum-1 servers) time *could* be more > stable since there are three stratum-1 servers involved, albeit through > the stratum-2 servers. > > This is a pure theoretical issue as far as I'm concerned, since who can > tell the difference if your servers are 23 milliseconds off... > So replace "stratum-1" by "stratum-N" and "stratum-2" by > "stratum-(N-1)"; the question will remain the same. > > Regards, > Timo
Think first about adding another server! Three servers can degenerate too easily to the two server case! When those two servers disagree. . . . _______________________________________________ questions mailing list [email protected] https://lists.ntp.isc.org/mailman/listinfo/questions
