several master ip's for a slave zone
barmar at alum.mit.edu
Mon Nov 7 03:54:40 UTC 2011
In article <mailman.1.1320621651.68562.bind-users at lists.isc.org>,
Chris Thompson <cet1 at cam.ac.uk> wrote:
> On Nov 5 2011, Alan Clegg wrote:
> >On 11/5/2011 4:21 AM, kalpesh varyani wrote:
> >> How does this feature address the risk that data provided by one master
> >> might get overwritten by another?
> >The use of the word "masters" in the configuration of a slave zone is a
> >bit misleading. Under most circumstances, you list the authoritative
> >servers, not "multiple masters".
> Although Alan doesn't say so, this might suggest to some that you should
> list *all* the authoritative servers. That's a very bad idea - you need
> to arrange that the directed graph of "A can fetch from B" is acyclic.
> Otherwise servers can get into the state that A thinks its copy of the
> zone is up to date because B told it so, and B thinks so because A told
> it so (or longer loops, of course), while neither of them are true masters
> for it.
I don't think it's a problem. As long as ANY of the servers in the
masters list have a higher serial number, you'll fetch from it.
So if you have three servers, A, B, and C, A will check the serial
numbers on both B and C, and pull from whichever has a higher serial
number than the serial A already has.
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