Min/Max Refresh and Notify

[Mike Diggins]

On Fri, 13 Dec 2002, Kevin Darcy wrote:

>
> Mike Diggins wrote:
>
> >I have a slave name server configured with a zone using min and max
> >refresh time.
> >
> What do you mean by "min and max refresh time"? There is only one
> REFRESH field in an SOA record.

It's a named.conf parameter in BIND 9. I'm using it on a test BIND server
to keep the mail abuse rbl from updating so often. The config below limits
it to twice a day. It's not under my control when it happens but that's
okay. I started sending notifies to this test slave server from the master
server and discovered it's back to updating every two hours.

zone "rbl-plus.mail-abuse.org" {
        type slave;
        file "data/rbl-plus.domain";
        allow-transfer { none; };
        max-refresh-time 43200;
        min-refresh-time 43200;
        masters {
                192.168.1.1
        };
};

-Mike


>
> >I was using it to limit the number of times the zone updates
> >to just two times a day.
> >
> >Question: If the master name server is configured to send notifies to the
> >slave when an update to the zone occurs, will the slave update the zone
> >anyway? That appears to be what's happening but I want to be sure. If it
> >is true, would turning off notifies to that slave for that one zone stop
> >that from happening?
> >
> Yes, you could turn off NOTIFYs and that would greatly reduce the number
> of refresh checks that the slave performs. But, be aware that the
> frequency with which BIND slaves perform refresh checks has a random
> element to it. This is done deliberately to prevent slave "cycling"
> which causes spikes of refresh-check and/or zone-transfer activity. So
> you can never *exactly* control when the slave will perform
> refresh-checks when you rely on the REFRESH setting alone.
>
> Perhaps you might consider turning off NOTIFYs to the slave within BIND
> and then using an artificial non-BIND method of sending NOTIFYs to the
> slave at specific intervals. I seem to recall there was a utility out
> there that could generate NOTIFYs, but I don't have a pointer to it
> handy. Perhaps someone else on the list could provide that information...
>
>
>                                     - Kevin
>
> >
> >
>
>
>
>


        **     *** ******    Mike Diggins
       ****  **** ********  Analyst, Networks
      ** ******* **     ** Computing and Information Services
     **   ** ** **     ** McMaster University, Hamilton, Ontario
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