> What does "stratum" exactly means? A host's stratum is the number of layers between that host and an accurate time source (atomic clock, GPS, etc). (Possibly plus or minus one depending on how you define the terms involved.)
My own pool host, for example, is stratum 3 at the moment; it is synced to time.nrc.ca, at stratum 2, which (according to ntptrace) is synced to some other NRC host at stratum 1; that host is connected to something authoritative - in the case of the NRC, quite likely an atomic clock. Or, at least, it's supposed to be connected to something authoritative; there's nothing actually preventing someone from setting up an inaccurate host and having it claim to be stratum 1. But it's not done often, and in the NRC's case I have basically no doubt that it really is what it's claiming to be. > I've set about 10 servers to the NTP pool, 8 of them has "stratum 2", > one has "stratum 3" and one became today "stratum 4". Very strange, > because that lasts server was "stratum 3". Hosts change strata not infrequently. A host's stratum is one higher than that of the source it's synced to; if it changes sync source, it may change stratum. If, for example, time.nrc crashes or becomes unreachable from my pool host, I'll resync to something else and (since that's my only stratum-2 source) change stratum. (My only stratum-2 source at the moment. But I know my other sources of chime well enough to know it's extremely unlikely that any of them will be of a stratum less than 3 in the foreseeable future.) /~\ The ASCII Mouse \ / Ribbon Campaign X Against HTML [email protected] / \ Email! 7D C8 61 52 5D E7 2D 39 4E F1 31 3E E8 B3 27 4B _______________________________________________ pool mailing list [email protected] http://lists.ntp.org/listinfo/pool
