preempt Option - NTP

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  1. preempt Option

    What exactly does the preempt option do?

    TIA


  2. Re: preempt Option

    TIA,

    If the interval between packets from a particular client is less than 2
    seconds of if the average interval is less than 16 seconds, the server
    returns a kiss-o'-death (KoD) packet and drops the client packet. This
    causes a compliant ntpd client to disable the association and show an
    appropriate kiss code. KoD packets can be sent for other reasons as
    well. Kiss codes are documented in the somftware distribution.

    Dave

    Evandro Menezes wrote:
    > What exactly does the preempt option do?
    >
    > TIA
    >


  3. Re: preempt Option

    Dave,

    Thanks for the reply, but I am confused by this:

    > If the interval between packets from a particular client is less than 2
    > seconds of if the average interval is less than 16 seconds...


    I should have been clear that my question is about the preempt option
    to the server configuration command. In your explanation, however, you
    refer to event in relation to the server, when this option configures a
    client.

    TIA


  4. Re: preempt Option

    TIA,

    No; the options is configured for the server, not the client.

    Dave

    evandro@mailandnews.com wrote:
    > Dave,
    >
    > Thanks for the reply, but I am confused by this:
    >
    >
    >>If the interval between packets from a particular client is less than 2
    >>seconds of if the average interval is less than 16 seconds...

    >
    >
    > I should have been clear that my question is about the preempt option
    > to the server configuration command. In your explanation, however, you
    > refer to event in relation to the server, when this option configures a
    > client.
    >
    > TIA
    >


  5. Re: preempt Option

    Dave,

    Here's what I see:

    I configure a server to have a preempt association. Instead of showing
    in the servers list with a KOD as you said, it doesn't show up at all.
    Will this preemptable server ever be contacted again?

    I came up the preempt server option because I wanted to have a backup
    server in case of failure of the main ones. But because this server
    runs Windows XP, it's pretty jittery, and because it was close and was
    of a higher stratum than other more consistent servers, it ended up
    being picked as the sync server. But in spite of NTP's decision, it's
    still a poor time reference.

    Or perhaps would letting the client do its best on its own be better
    than using a poor backup server?

    TIA


  6. Re: preempt Option

    TIA,

    I may have misread your original question. The preempt option is
    intended for the pool scheme and may not work as you expect. A
    preemptable association is expendable and presumed to exist only as the
    survivor of the selection algorithm which acts to cast off outlyers
    until a minimum number of survivors remain. Unless you really know what
    you are doing, it is probably best that you avoid this option.

    Dave

    evandro@mailandnews.com wrote:

    > Dave,
    >
    > Here's what I see:
    >
    > I configure a server to have a preempt association. Instead of showing
    > in the servers list with a KOD as you said, it doesn't show up at all.
    > Will this preemptable server ever be contacted again?
    >
    > I came up the preempt server option because I wanted to have a backup
    > server in case of failure of the main ones. But because this server
    > runs Windows XP, it's pretty jittery, and because it was close and was
    > of a higher stratum than other more consistent servers, it ended up
    > being picked as the sync server. But in spite of NTP's decision, it's
    > still a poor time reference.
    >
    > Or perhaps would letting the client do its best on its own be better
    > than using a poor backup server?
    >
    > TIA
    >


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