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At 12:51 PM -0700 5/17/01, Global Homes Webmaster wrote:
Re: Zone Transfer Q''s
From: Men & Mice Support
Date: Thursday, May 17, 2001
Time: 5:43:22 pm
>On 05/17/01 at 14:36, Juergen Schreck wrote:
>
> > I just recently had to switch ISP's. I'm running the Primary DNS
>at my place
> > and have the ISP do the secondary. In the logs I noticed that they were
> > loading zones every ten minutes, which seemed a bit often.
> >
> > I always thought the the REFRESH time was the primary measure for intervals
> > between zone loads. I'm using the default of 8 hours. I questioned them
> > about the frequent loads and here is what they said:
> >
> > >our name servers dont even have a parameter as far as transfer times
> > >except for when zoneload runs, or his server reloads, or the refresh time
> > >is hit.
> >
> > The middle one struck me. I checked my setting for rescanning
>zone files and
> > sure enough, it was set at 10 minutes. So that seems to be the reason their
> > servers load that often.
> >
> > Question: Is this appropriate? Or should they honor the refresh time only?
> > From what I can see, there is no way to turn of rescanning of zone files in
> > QNDS and the maximum is 60 minutes.
> >
> > Any suggestions?
>
>As I understand the rules of DNS, the slave server should be using the SOA
>refresh value to determine when to check to see if the zone has changed, which
>would require a zone transfer to get the changed data. The slave should look
>at the serial value in the zone's SOA -- if it's greater than the serial
>number in the slave's current data for the zone, it means that the zone has
>changed and the slave needs to do a zone transfer. If the serial is the same
>as what the slave has in it's current data, it should not need to reload the
>zone. The whole reason for the serial value in SOA records is to avoid
>unnecessary zone transfers.
That is pretty much correct. Their server can't tell when your server
rescans its zone files.
However, with servers other than QuickDNS, it's possible to define a
slave zone that isn't stored in a local file. Thus, when the server
restarts, it has no copy of the zone until it gets a zone transfer
from the master server.
If their server is being restarted every ten minutes, then that would
explain what's happening.
____________________________________________________________________
Chris Buxton Men & Mice
cbuxton@menandmice.com We Make DNS Easy!
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