How does bind select what master to use?
Barry Margolin
barmar at alum.mit.edu
Mon Apr 29 15:16:42 UTC 2013
In article <mailman.193.1367213994.20661.bind-users at lists.isc.org>,
Chris Buxton <clists at buxtonfamily.us> wrote:
> On Apr 27, 2013, at 5:52 AM, Matus UHLAR - fantomas wrote:
>
> > On 27.04.13 01:03, Kevin Morgan wrote:
> >> Does it use an algorithm to determine the best server to use or does
> >> it try the masters in the order they are listed? I am wondering if
> >> listing the masters in a different order can optimize the performance
> >> of bind.
> >
> > AFAIK:
> > BIND keeps track of servers accessible and their RTT. It tends to prefer
> > theone with shoertet RTT but ocasionally re-tries (RTT can change over
> > time. If notice comes, BIND tends to prefer server that has sent it.
>
> If you're talking masters, as in the BIND server is a slave refreshing from
> its masters, then I don't believe that's correct. I believe it compares the
> serial numbers retrieved from each and prefers the one with the highest
> value.
But if all of them have the same serial (and they're all higher than the
local value, of course), how does it decide which one to transfer from?
--
Barry Margolin
Arlington, MA
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