In article <[EMAIL PROTECTED]> Timo Ruiter <[EMAIL PROTECTED]> writes: $When you are assigned *one* stratum-1 server and *two* stratum-2 servers $your clock will obviously synchronize to the stratum-1 server.
Often, but not always. If (for instance) the delays between you and the stratum 1 server are severe or tend to bounce around a lot, you may find that you synchronize to one of the stratum 2 servers instead. I've noticed over the years that ntpd seems to have a fairly strong preference for stratum, but not so strong that it won't choose (say) a stratum 3 or 4 server over a stratum 2 server if the former seems better behaved than the latter. $ 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? That's another good use of them: it is a poor assumption that a given server will never go offline. Sooner or later, *every* server goes offline. You seem to be forgetting a couple of points about pool.ntp.org. One is that it is not intended to provide you with the absolute best time synchronization possible. It maintains a pool of servers, checks to make sure each one is reasonably accurate, and knows nothing about what the network paths between you and any of those servers might be. If you have a critical need for highly precise time synchronization, pool.ntp.org is not for you, as pointed out on the pool's Web site; you should choose servers manually, picking those which are highly accurate and close (in a network sense) to you, or you should hook your computer up to a hardware time source (perhaps something like a GPS device). If you just want to keep your clock's accuracy to within a fraction of a second, the pool should be good enough. The other is that the goal of the project is to try to spread the load reasonably evenly among participating servers. That was, in fact, the very reason for the pool's creation in the first place. If the pool were to track stratum and bias the pool towards using stratum 1 servers, those servers would experience heavy loads, and their owners would probably react by taking them out of the pool. That wouldn't benefit anyone. I manage three servers in the pool. They usually hang out within a few tens of milliseconds of The One True Time, according to both the pool's monitoring system and the output of ntpq -p. They're almost always stratum 3, as the servers used by them are typically at stratum 2. I realize that there are cases in which a machine might need a server with higher accuracy than that, but probably >99.99% of the machines hooked up to the Internet don't need anything better. -- Stephen M. Dunn <[EMAIL PROTECTED]> >>>----------------> http://www.stevedunn.ca/ <----------------<<< ------------------------------------------------------------------ Say hi to my cat -- http://www.stevedunn.ca/photos/toby/ _______________________________________________ questions mailing list [email protected] https://lists.ntp.isc.org/mailman/listinfo/questions
